[libcxx-commits] [libcxx] bec51c9 - [libc++][NFC] Remove the old PSTL headers

Nikolas Klauser via libcxx-commits libcxx-commits at lists.llvm.org
Fri Aug 11 08:29:23 PDT 2023


Author: Nikolas Klauser
Date: 2023-08-11T08:29:15-07:00
New Revision: bec51c907a74a0fa9ec138dc0a1bfc3d0b8eefd8

URL: https://github.com/llvm/llvm-project/commit/bec51c907a74a0fa9ec138dc0a1bfc3d0b8eefd8
DIFF: https://github.com/llvm/llvm-project/commit/bec51c907a74a0fa9ec138dc0a1bfc3d0b8eefd8.diff

LOG: [libc++][NFC] Remove the old PSTL headers

We don't actually use these headers, so we might as well remove them.

Reviewed By: ldionne, #libc

Spies: arichardson, EricWF, sstefan1, jplehr, wangpc, mgrang, libcxx-commits, miyuki

Differential Revision: https://reviews.llvm.org/D157558

Added: 
    

Modified: 
    libcxx/include/CMakeLists.txt
    libcxx/include/libcxx.imp
    libcxx/utils/data/ignore_format.txt

Removed: 
    libcxx/include/__pstl/internal/algorithm_fwd.h
    libcxx/include/__pstl/internal/algorithm_impl.h
    libcxx/include/__pstl/internal/execution_defs.h
    libcxx/include/__pstl/internal/execution_impl.h
    libcxx/include/__pstl/internal/glue_algorithm_defs.h
    libcxx/include/__pstl/internal/glue_algorithm_impl.h
    libcxx/include/__pstl/internal/glue_memory_defs.h
    libcxx/include/__pstl/internal/glue_memory_impl.h
    libcxx/include/__pstl/internal/glue_numeric_defs.h
    libcxx/include/__pstl/internal/glue_numeric_impl.h
    libcxx/include/__pstl/internal/memory_impl.h
    libcxx/include/__pstl/internal/numeric_fwd.h
    libcxx/include/__pstl/internal/numeric_impl.h
    libcxx/include/__pstl/internal/omp/parallel_for.h
    libcxx/include/__pstl/internal/omp/parallel_for_each.h
    libcxx/include/__pstl/internal/omp/parallel_invoke.h
    libcxx/include/__pstl/internal/omp/parallel_merge.h
    libcxx/include/__pstl/internal/omp/parallel_reduce.h
    libcxx/include/__pstl/internal/omp/parallel_scan.h
    libcxx/include/__pstl/internal/omp/parallel_stable_partial_sort.h
    libcxx/include/__pstl/internal/omp/parallel_stable_sort.h
    libcxx/include/__pstl/internal/omp/parallel_transform_reduce.h
    libcxx/include/__pstl/internal/omp/parallel_transform_scan.h
    libcxx/include/__pstl/internal/omp/util.h
    libcxx/include/__pstl/internal/parallel_backend.h
    libcxx/include/__pstl/internal/parallel_backend_omp.h
    libcxx/include/__pstl/internal/parallel_backend_serial.h
    libcxx/include/__pstl/internal/parallel_backend_tbb.h
    libcxx/include/__pstl/internal/parallel_backend_utils.h
    libcxx/include/__pstl/internal/unseq_backend_simd.h
    libcxx/include/__pstl/internal/utils.h
    libcxx/include/__pstl_algorithm
    libcxx/include/__pstl_config_site.in
    libcxx/include/__pstl_memory
    libcxx/include/__pstl_numeric


################################################################################
diff  --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index 58c700725447f6..28028955606118 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -561,39 +561,6 @@ set(files
   __numeric/transform_exclusive_scan.h
   __numeric/transform_inclusive_scan.h
   __numeric/transform_reduce.h
-  __pstl/internal/algorithm_fwd.h
-  __pstl/internal/algorithm_impl.h
-  __pstl/internal/execution_defs.h
-  __pstl/internal/execution_impl.h
-  __pstl/internal/glue_algorithm_defs.h
-  __pstl/internal/glue_algorithm_impl.h
-  __pstl/internal/glue_memory_defs.h
-  __pstl/internal/glue_memory_impl.h
-  __pstl/internal/glue_numeric_defs.h
-  __pstl/internal/glue_numeric_impl.h
-  __pstl/internal/memory_impl.h
-  __pstl/internal/numeric_fwd.h
-  __pstl/internal/numeric_impl.h
-  __pstl/internal/omp/parallel_for.h
-  __pstl/internal/omp/parallel_for_each.h
-  __pstl/internal/omp/parallel_invoke.h
-  __pstl/internal/omp/parallel_merge.h
-  __pstl/internal/omp/parallel_scan.h
-  __pstl/internal/omp/parallel_stable_partial_sort.h
-  __pstl/internal/omp/parallel_stable_sort.h
-  __pstl/internal/omp/parallel_transform_reduce.h
-  __pstl/internal/omp/parallel_transform_scan.h
-  __pstl/internal/omp/util.h
-  __pstl/internal/parallel_backend.h
-  __pstl/internal/parallel_backend_omp.h
-  __pstl/internal/parallel_backend_serial.h
-  __pstl/internal/parallel_backend_tbb.h
-  __pstl/internal/parallel_backend_utils.h
-  __pstl/internal/unseq_backend_simd.h
-  __pstl/internal/utils.h
-  __pstl_algorithm
-  __pstl_memory
-  __pstl_numeric
   __random/bernoulli_distribution.h
   __random/binomial_distribution.h
   __random/cauchy_distribution.h

diff  --git a/libcxx/include/__pstl/internal/algorithm_fwd.h b/libcxx/include/__pstl/internal/algorithm_fwd.h
deleted file mode 100644
index ba350392c2ac6d..00000000000000
--- a/libcxx/include/__pstl/internal/algorithm_fwd.h
+++ /dev/null
@@ -1,1768 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_ALGORITHM_FWD_H
-#define _PSTL_ALGORITHM_FWD_H
-
-#include <__config>
-#include <iterator>
-#include <type_traits>
-#include <utility>
-
-namespace __pstl {
-namespace __internal {
-
-//------------------------------------------------------------------------
-// walk1 (pseudo)
-//
-// walk1 evaluates f(x) for each dereferenced value x drawn from [first,last)
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _Function>
-void __brick_walk1(_ForwardIterator,
-                   _ForwardIterator,
-                   _Function,
-                   /*vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _Function>
-void __brick_walk1(_RandomAccessIterator,
-                   _RandomAccessIterator,
-                   _Function,
-                   /*vector=*/std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Function>
-void __pattern_walk1(_Tag, _ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, _Function) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Function>
-void __pattern_walk1(
-    __parallel_tag<_IsVector>, _ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator, _Function);
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Brick>
-void __pattern_walk_brick(_Tag, _ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, _Brick) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Brick>
-void __pattern_walk_brick(
-    __parallel_tag<_IsVector>, _ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator, _Brick);
-
-//------------------------------------------------------------------------
-// walk1_n
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _Size, class _Function>
-_ForwardIterator __brick_walk1_n(
-    _ForwardIterator,
-    _Size,
-    _Function,
-    /*_IsVectorTag=*/std::false_type);
-
-template <class _RandomAccessIterator, class _DifferenceType, class _Function>
-_RandomAccessIterator __brick_walk1_n(
-    _RandomAccessIterator,
-    _DifferenceType,
-    _Function,
-    /*vectorTag=*/std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Size, class _Function>
-_ForwardIterator __pattern_walk1_n(_Tag, _ExecutionPolicy&&, _ForwardIterator, _Size, _Function) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Size, class _Function>
-_RandomAccessIterator
-__pattern_walk1_n(__parallel_tag<_IsVector>, _ExecutionPolicy&&, _RandomAccessIterator, _Size, _Function);
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Size, class _Brick>
-_ForwardIterator __pattern_walk_brick_n(_Tag, _ExecutionPolicy&&, _ForwardIterator, _Size, _Brick) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Size, class _Brick>
-_RandomAccessIterator
-__pattern_walk_brick_n(__parallel_tag<_IsVector>, _ExecutionPolicy&&, _RandomAccessIterator, _Size, _Brick);
-
-//------------------------------------------------------------------------
-// walk2 (pseudo)
-//
-// walk2 evaluates f(x,y) for deferenced values (x,y) drawn from [first1,last1) and [first2,...)
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _Function>
-_ForwardIterator2 __brick_walk2(
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _Function,
-    /*vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _Function>
-_RandomAccessIterator2 __brick_walk2(
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _Function,
-    /*vector=*/std::true_type) noexcept;
-
-template <class _ForwardIterator1, class _Size, class _ForwardIterator2, class _Function>
-_ForwardIterator2 __brick_walk2_n(
-    _ForwardIterator1,
-    _Size,
-    _ForwardIterator2,
-    _Function,
-    /*vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator1, class _Size, class _RandomAccessIterator2, class _Function>
-_RandomAccessIterator2 __brick_walk2_n(
-    _RandomAccessIterator1,
-    _Size,
-    _RandomAccessIterator2,
-    _Function,
-    /*vector=*/std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Function>
-_ForwardIterator2
-__pattern_walk2(_Tag, _ExecutionPolicy&&, _ForwardIterator1, _ForwardIterator1, _ForwardIterator2, _Function) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _Function>
-_RandomAccessIterator2 __pattern_walk2(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _Function);
-
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _Size,
-          class _ForwardIterator2,
-          class _Function>
-_ForwardIterator2
-__pattern_walk2_n(_Tag, _ExecutionPolicy&&, _ForwardIterator1, _Size, _ForwardIterator2, _Function) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _Size,
-          class _RandomAccessIterator2,
-          class _Function>
-_RandomAccessIterator2 __pattern_walk2_n(
-    __parallel_tag<_IsVector>, _ExecutionPolicy&&, _RandomAccessIterator1, _Size, _RandomAccessIterator2, _Function);
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Brick>
-_ForwardIterator2 __pattern_walk2_brick(
-    _Tag, _ExecutionPolicy&&, _ForwardIterator1, _ForwardIterator1, _ForwardIterator2, _Brick) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _Brick>
-_RandomAccessIterator2 __pattern_walk2_brick(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _Brick);
-
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _Size,
-          class _ForwardIterator2,
-          class _Brick>
-_ForwardIterator2
-__pattern_walk2_brick_n(_Tag, _ExecutionPolicy&&, _ForwardIterator1, _Size, _ForwardIterator2, _Brick) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _Size,
-          class _RandomAccessIterator2,
-          class _Brick>
-_RandomAccessIterator2 __pattern_walk2_brick_n(
-    __parallel_tag<_IsVector>, _ExecutionPolicy&&, _RandomAccessIterator1, _Size, _RandomAccessIterator2, _Brick);
-
-//------------------------------------------------------------------------
-// walk3 (pseudo)
-//
-// walk3 evaluates f(x,y,z) for (x,y,z) drawn from [first1,last1), [first2,...), [first3,...)
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _ForwardIterator3, class _Function>
-_ForwardIterator3 __brick_walk3(
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator3,
-    _Function,
-    /*vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _RandomAccessIterator3, class _Function>
-_RandomAccessIterator3 __brick_walk3(
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator3,
-    _Function,
-    /*vector=*/std::true_type) noexcept;
-
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _ForwardIterator3,
-          class _Function>
-_ForwardIterator3 __pattern_walk3(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator3,
-    _Function) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _RandomAccessIterator3,
-          class _Function>
-_RandomAccessIterator3 __pattern_walk3(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator3,
-    _Function);
-
-//------------------------------------------------------------------------
-// equal
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-bool __brick_equal(_ForwardIterator1,
-                   _ForwardIterator1,
-                   _ForwardIterator2,
-                   _BinaryPredicate,
-                   /* is_vector = */ std::false_type) noexcept;
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
-bool __brick_equal(_RandomAccessIterator1,
-                   _RandomAccessIterator1,
-                   _RandomAccessIterator2,
-                   _BinaryPredicate,
-                   /* is_vector = */ std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-bool __pattern_equal(
-    _Tag, _ExecutionPolicy&&, _ForwardIterator1, _ForwardIterator1, _ForwardIterator2, _BinaryPredicate) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _BinaryPredicate>
-bool __pattern_equal(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _BinaryPredicate);
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-bool __brick_equal(_ForwardIterator1,
-                   _ForwardIterator1,
-                   _ForwardIterator2,
-                   _ForwardIterator2,
-                   _BinaryPredicate,
-                   /* is_vector = */ std::false_type) noexcept;
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
-bool __brick_equal(_RandomAccessIterator1,
-                   _RandomAccessIterator1,
-                   _RandomAccessIterator2,
-                   _RandomAccessIterator2,
-                   _BinaryPredicate,
-                   /* is_vector = */ std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-bool __pattern_equal(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _BinaryPredicate) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _BinaryPredicate>
-bool __pattern_equal(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _BinaryPredicate);
-
-//------------------------------------------------------------------------
-// find_end
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-_ForwardIterator1 __brick_find_end(
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _BinaryPredicate,
-    /*__is_vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
-_RandomAccessIterator1 __brick_find_end(
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _BinaryPredicate,
-    /*__is_vector=*/std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-_ForwardIterator1 __pattern_find_end(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _BinaryPredicate) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _BinaryPredicate>
-_RandomAccessIterator1 __pattern_find_end(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _BinaryPredicate) noexcept;
-
-//------------------------------------------------------------------------
-// find_first_of
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-_ForwardIterator1 __brick_find_first_of(
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _BinaryPredicate,
-    /*__is_vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
-_RandomAccessIterator1 __brick_find_first_of(
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _BinaryPredicate,
-    /*__is_vector=*/std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-_ForwardIterator1 __pattern_find_first_of(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _BinaryPredicate) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _BinaryPredicate>
-_RandomAccessIterator1 __pattern_find_first_of(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _BinaryPredicate) noexcept;
-
-//------------------------------------------------------------------------
-// search
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-_ForwardIterator1 __brick_search(
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _BinaryPredicate,
-    /*vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
-_RandomAccessIterator1 __brick_search(
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _BinaryPredicate,
-    /*vector=*/std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-_ForwardIterator1 __pattern_search(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _BinaryPredicate) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _BinaryPredicate>
-_RandomAccessIterator1 __pattern_search(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _BinaryPredicate) noexcept;
-
-//------------------------------------------------------------------------
-// search_n
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate>
-_ForwardIterator __brick_search_n(
-    _ForwardIterator,
-    _ForwardIterator,
-    _Size,
-    const _Tp&,
-    _BinaryPredicate,
-    /*vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _Size, class _Tp, class _BinaryPredicate>
-_RandomAccessIterator __brick_search_n(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _Size,
-    const _Tp&,
-    _BinaryPredicate,
-    /*vector=*/std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate>
-_ForwardIterator __pattern_search_n(
-    _Tag, _ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, _Size, const _Tp&, _BinaryPredicate) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator,
-          class _Size,
-          class _Tp,
-          class _BinaryPredicate>
-_RandomAccessIterator __pattern_search_n(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _Size,
-    const _Tp&,
-    _BinaryPredicate) noexcept;
-
-//------------------------------------------------------------------------
-// copy_n
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _Size, class _OutputIterator>
-_OutputIterator __brick_copy_n(_ForwardIterator,
-                               _Size,
-                               _OutputIterator,
-                               /*vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _Size, class _OutputIterator>
-_OutputIterator __brick_copy_n(_RandomAccessIterator,
-                               _Size,
-                               _OutputIterator,
-                               /*vector=*/std::true_type) noexcept;
-
-//------------------------------------------------------------------------
-// copy
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _OutputIterator>
-_OutputIterator __brick_copy(_ForwardIterator,
-                             _ForwardIterator,
-                             _OutputIterator,
-                             /*vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _OutputIterator>
-_OutputIterator __brick_copy(_RandomAccessIterator,
-                             _RandomAccessIterator,
-                             _OutputIterator,
-                             /*vector=*/std::true_type) noexcept;
-
-//------------------------------------------------------------------------
-// move
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _OutputIterator>
-_OutputIterator __brick_move(_ForwardIterator,
-                             _ForwardIterator,
-                             _OutputIterator,
-                             /*vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _OutputIterator>
-_OutputIterator __brick_move(_RandomAccessIterator,
-                             _RandomAccessIterator,
-                             _OutputIterator,
-                             /*vector=*/std::true_type) noexcept;
-
-//------------------------------------------------------------------------
-// swap_ranges
-//------------------------------------------------------------------------
-template <class _ForwardIterator, class _OutputIterator>
-_OutputIterator __brick_swap_ranges(
-    _ForwardIterator,
-    _ForwardIterator,
-    _OutputIterator,
-    /*vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _OutputIterator>
-_OutputIterator __brick_swap_ranges(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _OutputIterator,
-    /*vector=*/std::true_type) noexcept;
-
-//------------------------------------------------------------------------
-// copy_if
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _OutputIterator, class _UnaryPredicate>
-_OutputIterator __brick_copy_if(
-    _ForwardIterator,
-    _ForwardIterator,
-    _OutputIterator,
-    _UnaryPredicate,
-    /*vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _OutputIterator, class _UnaryPredicate>
-_OutputIterator __brick_copy_if(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _OutputIterator,
-    _UnaryPredicate,
-    /*vector=*/std::true_type) noexcept;
-
-template <class _DifferenceType, class _ForwardIterator, class _UnaryPredicate>
-std::pair<_DifferenceType, _DifferenceType> __brick_calc_mask_1(
-    _ForwardIterator,
-    _ForwardIterator,
-    bool* __restrict,
-    _UnaryPredicate,
-    /*vector=*/std::false_type) noexcept;
-template <class _DifferenceType, class _RandomAccessIterator, class _UnaryPredicate>
-std::pair<_DifferenceType, _DifferenceType> __brick_calc_mask_1(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    bool* __restrict,
-    _UnaryPredicate,
-    /*vector=*/std::true_type) noexcept;
-
-template <class _ForwardIterator, class _OutputIterator>
-void __brick_copy_by_mask(
-    _ForwardIterator,
-    _ForwardIterator,
-    _OutputIterator,
-    bool*,
-    /*vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _OutputIterator>
-void __brick_copy_by_mask(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _OutputIterator,
-    bool* __restrict,
-    /*vector=*/std::true_type) noexcept;
-
-template <class _ForwardIterator, class _OutputIterator1, class _OutputIterator2>
-void __brick_partition_by_mask(
-    _ForwardIterator,
-    _ForwardIterator,
-    _OutputIterator1,
-    _OutputIterator2,
-    bool*,
-    /*vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _OutputIterator1, class _OutputIterator2>
-void __brick_partition_by_mask(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _OutputIterator1,
-    _OutputIterator2,
-    bool*,
-    /*vector=*/std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _OutputIterator, class _UnaryPredicate>
-_OutputIterator __pattern_copy_if(
-    _Tag, _ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, _OutputIterator, _UnaryPredicate) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator,
-          class _OutputIterator,
-          class _UnaryPredicate>
-_OutputIterator __pattern_copy_if(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _OutputIterator,
-    _UnaryPredicate);
-
-//------------------------------------------------------------------------
-// count
-//------------------------------------------------------------------------
-
-template <class _RandomAccessIterator, class _Predicate>
-typename std::iterator_traits<_RandomAccessIterator>::
diff erence_type __brick_count(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _Predicate,
-    /* is_vector = */ std::true_type) noexcept;
-
-template <class _ForwardIterator, class _Predicate>
-typename std::iterator_traits<_ForwardIterator>::
diff erence_type __brick_count(
-    _ForwardIterator,
-    _ForwardIterator,
-    _Predicate,
-    /* is_vector = */ std::false_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Predicate>
-typename std::iterator_traits<_ForwardIterator>::
diff erence_type
-__pattern_count(_Tag, _ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, _Predicate) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Predicate>
-typename std::iterator_traits<_RandomAccessIterator>::
diff erence_type __pattern_count(
-    __parallel_tag<_IsVector>, _ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator, _Predicate);
-
-//------------------------------------------------------------------------
-// unique
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _BinaryPredicate>
-_ForwardIterator __brick_unique(
-    _ForwardIterator,
-    _ForwardIterator,
-    _BinaryPredicate,
-    /*is_vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _BinaryPredicate>
-_RandomAccessIterator __brick_unique(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _BinaryPredicate,
-    /*is_vector=*/std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _BinaryPredicate>
-_ForwardIterator
-__pattern_unique(_Tag, _ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, _BinaryPredicate) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _BinaryPredicate>
-_RandomAccessIterator __pattern_unique(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _BinaryPredicate) noexcept;
-
-//------------------------------------------------------------------------
-// unique_copy
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class OutputIterator, class _BinaryPredicate>
-OutputIterator __brick_unique_copy(
-    _ForwardIterator,
-    _ForwardIterator,
-    OutputIterator,
-    _BinaryPredicate,
-    /*vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _OutputIterator, class _BinaryPredicate>
-_OutputIterator __brick_unique_copy(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _OutputIterator,
-    _BinaryPredicate,
-    /*vector=*/std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _OutputIterator, class _BinaryPredicate>
-_OutputIterator __pattern_unique_copy(
-    _Tag, _ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, _OutputIterator, _BinaryPredicate) noexcept;
-
-template <class _ExecutionPolicy, class _DifferenceType, class _RandomAccessIterator, class _BinaryPredicate>
-_DifferenceType __brick_calc_mask_2(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    bool* __restrict,
-    _BinaryPredicate,
-    /*vector=*/std::false_type) noexcept;
-
-template <class _DifferenceType, class _RandomAccessIterator, class _BinaryPredicate>
-_DifferenceType __brick_calc_mask_2(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    bool* __restrict,
-    _BinaryPredicate,
-    /*vector=*/std::true_type) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator,
-          class _OutputIterator,
-          class _BinaryPredicate>
-_OutputIterator __pattern_unique_copy(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _OutputIterator,
-    _BinaryPredicate);
-
-//------------------------------------------------------------------------
-// reverse
-//------------------------------------------------------------------------
-
-template <class _BidirectionalIterator>
-void __brick_reverse(_BidirectionalIterator,
-                     _BidirectionalIterator,
-                     /*__is_vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator>
-void __brick_reverse(_RandomAccessIterator,
-                     _RandomAccessIterator,
-                     /*__is_vector=*/std::true_type) noexcept;
-
-template <class _BidirectionalIterator>
-void __brick_reverse(_BidirectionalIterator,
-                     _BidirectionalIterator,
-                     _BidirectionalIterator,
-                     /*is_vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator>
-void __brick_reverse(_RandomAccessIterator,
-                     _RandomAccessIterator,
-                     _RandomAccessIterator,
-                     /*is_vector=*/std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _BidirectionalIterator>
-void __pattern_reverse(_Tag, _ExecutionPolicy&&, _BidirectionalIterator, _BidirectionalIterator) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator>
-void __pattern_reverse(__parallel_tag<_IsVector>, _ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator);
-
-//------------------------------------------------------------------------
-// reverse_copy
-//------------------------------------------------------------------------
-
-template <class _BidirectionalIterator, class _OutputIterator>
-_OutputIterator __brick_reverse_copy(
-    _BidirectionalIterator,
-    _BidirectionalIterator,
-    _OutputIterator,
-    /*is_vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _OutputIterator>
-_OutputIterator __brick_reverse_copy(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _OutputIterator,
-    /*is_vector=*/std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _BidirectionalIterator, class _OutputIterator>
-_OutputIterator __pattern_reverse_copy(
-    _Tag, _ExecutionPolicy&&, _BidirectionalIterator, _BidirectionalIterator, _OutputIterator) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _OutputIterator>
-_OutputIterator __pattern_reverse_copy(
-    __parallel_tag<_IsVector>, _ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator, _OutputIterator);
-
-//------------------------------------------------------------------------
-// rotate
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator>
-_ForwardIterator __brick_rotate(
-    _ForwardIterator,
-    _ForwardIterator,
-    _ForwardIterator,
-    /*is_vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator>
-_RandomAccessIterator __brick_rotate(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    /*is_vector=*/std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator>
-_ForwardIterator
-__pattern_rotate(_Tag, _ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, _ForwardIterator) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator>
-_RandomAccessIterator __pattern_rotate(
-    __parallel_tag<_IsVector>, _ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator, _RandomAccessIterator);
-
-//------------------------------------------------------------------------
-// rotate_copy
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _OutputIterator>
-_OutputIterator __brick_rotate_copy(
-    _ForwardIterator,
-    _ForwardIterator,
-    _ForwardIterator,
-    _OutputIterator,
-    /*__is_vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _OutputIterator>
-_OutputIterator __brick_rotate_copy(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _OutputIterator,
-    /*__is_vector=*/std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _OutputIterator>
-_OutputIterator __pattern_rotate_copy(
-    _Tag, _ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, _ForwardIterator, _OutputIterator) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _OutputIterator>
-_OutputIterator __pattern_rotate_copy(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _OutputIterator);
-
-//------------------------------------------------------------------------
-// is_partitioned
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _UnaryPredicate>
-bool __brick_is_partitioned(_ForwardIterator,
-                            _ForwardIterator,
-                            _UnaryPredicate,
-                            /*is_vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _UnaryPredicate>
-bool __brick_is_partitioned(_RandomAccessIterator,
-                            _RandomAccessIterator,
-                            _UnaryPredicate,
-                            /*is_vector=*/std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate>
-bool __pattern_is_partitioned(_Tag, _ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, _UnaryPredicate) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _UnaryPredicate>
-bool __pattern_is_partitioned(
-    __parallel_tag<_IsVector>, _ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator, _UnaryPredicate);
-
-//------------------------------------------------------------------------
-// partition
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _UnaryPredicate>
-_ForwardIterator __brick_partition(
-    _ForwardIterator,
-    _ForwardIterator,
-    _UnaryPredicate,
-    /*is_vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _UnaryPredicate>
-_RandomAccessIterator __brick_partition(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _UnaryPredicate,
-    /*is_vector=*/std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate>
-_ForwardIterator
-__pattern_partition(_Tag, _ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, _UnaryPredicate) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _UnaryPredicate>
-_RandomAccessIterator __pattern_partition(
-    __parallel_tag<_IsVector>, _ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator, _UnaryPredicate);
-
-//------------------------------------------------------------------------
-// stable_partition
-//------------------------------------------------------------------------
-
-template <class _BidirectionalIterator, class _UnaryPredicate>
-_BidirectionalIterator __brick_stable_partition(
-    _BidirectionalIterator,
-    _BidirectionalIterator,
-    _UnaryPredicate,
-    /*__is_vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _UnaryPredicate>
-_RandomAccessIterator __brick_stable_partition(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _UnaryPredicate,
-    /*__is_vector=*/std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _BidirectionalIterator, class _UnaryPredicate>
-_BidirectionalIterator __pattern_stable_partition(
-    _Tag, _ExecutionPolicy&&, _BidirectionalIterator, _BidirectionalIterator, _UnaryPredicate) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _UnaryPredicate>
-_RandomAccessIterator __pattern_stable_partition(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _UnaryPredicate) noexcept;
-
-//------------------------------------------------------------------------
-// partition_copy
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _OutputIterator1, class _OutputIterator2, class _UnaryPredicate>
-std::pair<_OutputIterator1, _OutputIterator2> __brick_partition_copy(
-    _ForwardIterator,
-    _ForwardIterator,
-    _OutputIterator1,
-    _OutputIterator2,
-    _UnaryPredicate,
-    /*is_vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _OutputIterator1, class _OutputIterator2, class _UnaryPredicate>
-std::pair<_OutputIterator1, _OutputIterator2> __brick_partition_copy(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _OutputIterator1,
-    _OutputIterator2,
-    _UnaryPredicate,
-    /*is_vector=*/std::true_type) noexcept;
-
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _ForwardIterator,
-          class _OutputIterator1,
-          class _OutputIterator2,
-          class _UnaryPredicate>
-std::pair<_OutputIterator1, _OutputIterator2> __pattern_partition_copy(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator,
-    _ForwardIterator,
-    _OutputIterator1,
-    _OutputIterator2,
-    _UnaryPredicate) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator,
-          class _OutputIterator1,
-          class _OutputIterator2,
-          class _UnaryPredicate>
-std::pair<_OutputIterator1, _OutputIterator2> __pattern_partition_copy(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _OutputIterator1,
-    _OutputIterator2,
-    _UnaryPredicate);
-
-//------------------------------------------------------------------------
-// sort
-//------------------------------------------------------------------------
-
-template <class _Tag, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare, class _IsMoveConstructible>
-void __pattern_sort(
-    _Tag, _ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator, _Compare, _IsMoveConstructible) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-void __pattern_sort(__parallel_tag<_IsVector>,
-                    _ExecutionPolicy&&,
-                    _RandomAccessIterator,
-                    _RandomAccessIterator,
-                    _Compare,
-                    /*is_move_constructible=*/std::true_type);
-
-//------------------------------------------------------------------------
-// stable_sort
-//------------------------------------------------------------------------
-
-template <class _Tag, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-void __pattern_stable_sort(_Tag, _ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator, _Compare) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-void __pattern_stable_sort(
-    __parallel_tag<_IsVector>, _ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator, _Compare);
-
-//------------------------------------------------------------------------
-// partial_sort
-//------------------------------------------------------------------------
-
-template <class _Tag, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-void __pattern_partial_sort(
-    _Tag, _ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator, _RandomAccessIterator, _Compare) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-void __pattern_partial_sort(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _Compare);
-
-//------------------------------------------------------------------------
-// partial_sort_copy
-//------------------------------------------------------------------------
-
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _Compare>
-_RandomAccessIterator2 __pattern_partial_sort_copy(
-    _Tag,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _Compare) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _Compare>
-_RandomAccessIterator2 __pattern_partial_sort_copy(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _Compare);
-
-//------------------------------------------------------------------------
-// adjacent_find
-//------------------------------------------------------------------------
-
-template <class _RandomAccessIterator, class _BinaryPredicate>
-_RandomAccessIterator __brick_adjacent_find(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _BinaryPredicate,
-    /* IsVector = */ std::true_type,
-    bool) noexcept;
-
-template <class _ForwardIterator, class _BinaryPredicate>
-_ForwardIterator __brick_adjacent_find(
-    _ForwardIterator,
-    _ForwardIterator,
-    _BinaryPredicate,
-    /* IsVector = */ std::false_type,
-    bool) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _BinaryPredicate>
-_ForwardIterator
-__pattern_adjacent_find(_Tag, _ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, _BinaryPredicate, bool) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _BinaryPredicate>
-_RandomAccessIterator __pattern_adjacent_find(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _BinaryPredicate,
-    bool);
-
-//------------------------------------------------------------------------
-// nth_element
-//------------------------------------------------------------------------
-template <class _Tag, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-void __pattern_nth_element(
-    _Tag, _ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator, _RandomAccessIterator, _Compare) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-void __pattern_nth_element(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _Compare) noexcept;
-
-//------------------------------------------------------------------------
-// fill, fill_n
-//------------------------------------------------------------------------
-template <class _RandomAccessIterator, class _Tp>
-void __brick_fill(_RandomAccessIterator,
-                  _RandomAccessIterator,
-                  const _Tp&,
-                  /* __is_vector = */ std::true_type) noexcept;
-
-template <class _ForwardIterator, class _Tp>
-void __brick_fill(_ForwardIterator,
-                  _ForwardIterator,
-                  const _Tp&,
-                  /* __is_vector = */ std::false_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Tp>
-void __pattern_fill(_Tag, _ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, const _Tp&) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Tp>
-_RandomAccessIterator
-__pattern_fill(__parallel_tag<_IsVector>, _ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator, const _Tp&);
-
-template <class _RandomAccessIterator, class _Size, class _Tp>
-_RandomAccessIterator
-__brick_fill_n(_RandomAccessIterator,
-               _Size,
-               const _Tp&,
-               /* __is_vector = */ std::true_type) noexcept;
-
-template <class _OutputIterator, class _Size, class _Tp>
-_OutputIterator
-__brick_fill_n(_OutputIterator,
-               _Size,
-               const _Tp&,
-               /* __is_vector = */ std::false_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _OutputIterator, class _Size, class _Tp>
-_OutputIterator __pattern_fill_n(_Tag, _ExecutionPolicy&&, _OutputIterator, _Size, const _Tp&) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Size, class _Tp>
-_RandomAccessIterator
-__pattern_fill_n(__parallel_tag<_IsVector>, _ExecutionPolicy&&, _RandomAccessIterator, _Size, const _Tp&);
-
-//------------------------------------------------------------------------
-// generate, generate_n
-//------------------------------------------------------------------------
-
-template <class _RandomAccessIterator, class _Generator>
-void __brick_generate(_RandomAccessIterator,
-                      _RandomAccessIterator,
-                      _Generator,
-                      /* is_vector = */ std::true_type) noexcept;
-
-template <class _ForwardIterator, class _Generator>
-void __brick_generate(_ForwardIterator,
-                      _ForwardIterator,
-                      _Generator,
-                      /* is_vector = */ std::false_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Generator>
-void __pattern_generate(_Tag, _ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, _Generator) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Generator>
-_RandomAccessIterator __pattern_generate(
-    __parallel_tag<_IsVector>, _ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator, _Generator);
-
-template <class _RandomAccessIterator, class Size, class _Generator>
-_RandomAccessIterator __brick_generate_n(
-    _RandomAccessIterator,
-    Size,
-    _Generator,
-    /* is_vector = */ std::true_type) noexcept;
-
-template <class OutputIterator, class Size, class _Generator>
-OutputIterator __brick_generate_n(
-    OutputIterator,
-    Size,
-    _Generator,
-    /* is_vector = */ std::false_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class OutputIterator, class Size, class _Generator>
-OutputIterator __pattern_generate_n(_Tag, _ExecutionPolicy&&, OutputIterator, Size, _Generator) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class Size, class _Generator>
-_RandomAccessIterator
-__pattern_generate_n(__parallel_tag<_IsVector>, _ExecutionPolicy&&, _RandomAccessIterator, Size, _Generator);
-
-//------------------------------------------------------------------------
-// remove
-//------------------------------------------------------------------------
-template <class _ForwardIterator, class _UnaryPredicate>
-_ForwardIterator __brick_remove_if(
-    _ForwardIterator,
-    _ForwardIterator,
-    _UnaryPredicate,
-    /* __is_vector = */ std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _UnaryPredicate>
-_RandomAccessIterator __brick_remove_if(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _UnaryPredicate,
-    /* __is_vector = */ std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate>
-_ForwardIterator
-__pattern_remove_if(_Tag, _ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, _UnaryPredicate) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _UnaryPredicate>
-_RandomAccessIterator __pattern_remove_if(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _UnaryPredicate) noexcept;
-
-//------------------------------------------------------------------------
-// merge
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
-_OutputIterator __brick_merge(
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _OutputIterator,
-    _Compare,
-    /* __is_vector = */ std::false_type) noexcept;
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _OutputIterator, class _Compare>
-_OutputIterator __brick_merge(
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _OutputIterator,
-    _Compare,
-    /* __is_vector = */ std::true_type) noexcept;
-
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _OutputIterator,
-          class _Compare>
-_OutputIterator __pattern_merge(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _OutputIterator,
-    _Compare) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _OutputIterator,
-          class _Compare>
-_OutputIterator __pattern_merge(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _OutputIterator,
-    _Compare);
-
-//------------------------------------------------------------------------
-// inplace_merge
-//------------------------------------------------------------------------
-
-template <class _BidirectionalIterator, class _Compare>
-void __brick_inplace_merge(
-    _BidirectionalIterator,
-    _BidirectionalIterator,
-    _BidirectionalIterator,
-    _Compare,
-    /* __is_vector = */ std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _Compare>
-void __brick_inplace_merge(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _Compare,
-    /* __is_vector = */ std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _BidirectionalIterator, class _Compare>
-void __pattern_inplace_merge(
-    _Tag,
-    _ExecutionPolicy&&,
-    _BidirectionalIterator,
-    _BidirectionalIterator,
-    _BidirectionalIterator,
-    _Compare) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-void __pattern_inplace_merge(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _Compare);
-
-//------------------------------------------------------------------------
-// includes
-//------------------------------------------------------------------------
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Compare>
-bool __pattern_includes(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _Compare) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _Compare>
-bool __pattern_includes(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _Compare);
-
-//------------------------------------------------------------------------
-// set_union
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
-_OutputIterator __brick_set_union(
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _OutputIterator,
-    _Compare,
-    /*__is_vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _OutputIterator, class _Compare>
-_OutputIterator __brick_set_union(
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _OutputIterator,
-    _Compare,
-    /*__is_vector=*/std::true_type) noexcept;
-
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _OutputIterator,
-          class _Compare>
-_OutputIterator __pattern_set_union(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _OutputIterator,
-    _Compare) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _OutputIterator,
-          class _Compare>
-_OutputIterator __pattern_set_union(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _OutputIterator,
-    _Compare);
-
-//------------------------------------------------------------------------
-// set_intersection
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
-_OutputIterator __brick_set_intersection(
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _OutputIterator,
-    _Compare,
-    /*__is_vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _OutputIterator, class _Compare>
-_OutputIterator __brick_set_intersection(
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _OutputIterator,
-    _Compare,
-    /*__is_vector=*/std::true_type) noexcept;
-
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _OutputIterator,
-          class _Compare>
-_OutputIterator __pattern_set_intersection(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _OutputIterator,
-    _Compare) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _OutputIterator,
-          class _Compare>
-_OutputIterator __pattern_set_intersection(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _OutputIterator,
-    _Compare);
-
-//------------------------------------------------------------------------
-// set_
diff erence
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
-_OutputIterator __brick_set_
diff erence(
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _OutputIterator,
-    _Compare,
-    /*__is_vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _OutputIterator, class _Compare>
-_OutputIterator __brick_set_
diff erence(
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _OutputIterator,
-    _Compare,
-    /*__is_vector=*/std::true_type) noexcept;
-
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _OutputIterator,
-          class _Compare>
-_OutputIterator __pattern_set_
diff erence(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _OutputIterator,
-    _Compare) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _OutputIterator,
-          class _Compare>
-_OutputIterator __pattern_set_
diff erence(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _OutputIterator,
-    _Compare);
-
-//------------------------------------------------------------------------
-// set_symmetric_
diff erence
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
-_OutputIterator __brick_set_symmetric_
diff erence(
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _OutputIterator,
-    _Compare,
-    /*__is_vector=*/std::false_type) noexcept;
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _OutputIterator, class _Compare>
-_OutputIterator __brick_set_symmetric_
diff erence(
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _OutputIterator,
-    _Compare,
-    /*__is_vector=*/std::true_type) noexcept;
-
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _OutputIterator,
-          class _Compare>
-_OutputIterator __pattern_set_symmetric_
diff erence(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _OutputIterator,
-    _Compare) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _OutputIterator,
-          class _Compare>
-_OutputIterator __pattern_set_symmetric_
diff erence(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _OutputIterator,
-    _Compare);
-
-//------------------------------------------------------------------------
-// is_heap_until
-//------------------------------------------------------------------------
-
-template <class _RandomAccessIterator, class _Compare>
-_RandomAccessIterator __brick_is_heap_until(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _Compare,
-    /* __is_vector = */ std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _Compare>
-_RandomAccessIterator __brick_is_heap_until(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _Compare,
-    /* __is_vector = */ std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-_RandomAccessIterator
-__pattern_is_heap_until(_Tag, _ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator, _Compare) noexcept;
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-_RandomAccessIterator __pattern_is_heap_until(
-    __parallel_tag<_IsVector>, _ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator, _Compare) noexcept;
-
-//------------------------------------------------------------------------
-// min_element
-//------------------------------------------------------------------------
-
-template <typename _ForwardIterator, typename _Compare>
-_ForwardIterator __brick_min_element(
-    _ForwardIterator,
-    _ForwardIterator,
-    _Compare,
-    /* __is_vector = */ std::false_type) noexcept;
-
-template <typename _RandomAccessIterator, typename _Compare>
-_RandomAccessIterator __brick_min_element(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _Compare,
-    /* __is_vector = */ std::true_type) noexcept;
-
-template <typename _Tag, typename _ExecutionPolicy, typename _ForwardIterator, typename _Compare>
-_ForwardIterator __pattern_min_element(_Tag, _ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, _Compare) noexcept;
-
-template <typename _IsVector, typename _ExecutionPolicy, typename _RandomAccessIterator, typename _Compare>
-_RandomAccessIterator __pattern_min_element(
-    __parallel_tag<_IsVector>, _ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator, _Compare);
-
-//------------------------------------------------------------------------
-// minmax_element
-//------------------------------------------------------------------------
-
-template <typename _ForwardIterator, typename _Compare>
-std::pair<_ForwardIterator, _ForwardIterator> __brick_minmax_element(
-    _ForwardIterator,
-    _ForwardIterator,
-    _Compare,
-    /* __is_vector = */ std::false_type) noexcept;
-
-template <typename _RandomAccessIterator, typename _Compare>
-std::pair<_RandomAccessIterator, _RandomAccessIterator> __brick_minmax_element(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _Compare,
-    /* __is_vector = */ std::true_type) noexcept;
-
-template <typename _Tag, typename _ExecutionPolicy, typename _ForwardIterator, typename _Compare>
-std::pair<_ForwardIterator, _ForwardIterator>
-__pattern_minmax_element(_Tag, _ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, _Compare) noexcept;
-
-template <typename _IsVector, typename _ExecutionPolicy, typename _RandomAccessIterator, typename _Compare>
-std::pair<_RandomAccessIterator, _RandomAccessIterator> __pattern_minmax_element(
-    __parallel_tag<_IsVector>, _ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator, _Compare);
-
-//------------------------------------------------------------------------
-// mismatch
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _Predicate>
-std::pair<_ForwardIterator1, _ForwardIterator2> __brick_mismatch(
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _Predicate,
-    /* __is_vector = */ std::false_type) noexcept;
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _Predicate>
-std::pair<_RandomAccessIterator1, _RandomAccessIterator2> __brick_mismatch(
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _Predicate,
-    /* __is_vector = */ std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Predicate>
-std::pair<_ForwardIterator1, _ForwardIterator2> __pattern_mismatch(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _Predicate) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _Predicate>
-std::pair<_RandomAccessIterator1, _RandomAccessIterator2> __pattern_mismatch(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _Predicate) noexcept;
-
-//------------------------------------------------------------------------
-// lexicographical_compare
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _Compare>
-bool __brick_lexicographical_compare(
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _Compare,
-    /* __is_vector = */ std::false_type) noexcept;
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _Compare>
-bool __brick_lexicographical_compare(
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _Compare,
-    /* __is_vector = */ std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Compare>
-bool __pattern_lexicographical_compare(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1,
-    _ForwardIterator1,
-    _ForwardIterator2,
-    _ForwardIterator2,
-    _Compare) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _Compare>
-bool __pattern_lexicographical_compare(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator1,
-    _RandomAccessIterator1,
-    _RandomAccessIterator2,
-    _RandomAccessIterator2,
-    _Compare) noexcept;
-
-} // namespace __internal
-} // namespace __pstl
-
-#endif /* _PSTL_ALGORITHM_FWD_H */

diff  --git a/libcxx/include/__pstl/internal/algorithm_impl.h b/libcxx/include/__pstl/internal/algorithm_impl.h
deleted file mode 100644
index 72043ebbf76234..00000000000000
--- a/libcxx/include/__pstl/internal/algorithm_impl.h
+++ /dev/null
@@ -1,4174 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_ALGORITHM_IMPL_H
-#define _PSTL_ALGORITHM_IMPL_H
-
-#include <__assert>
-#include <__config>
-#include <algorithm>
-#include <functional>
-#include <iterator>
-#include <type_traits>
-#include <utility>
-
-#include "execution_impl.h"
-#include "memory_impl.h"
-#include "parallel_backend.h"
-#include "parallel_backend_utils.h"
-#include "parallel_impl.h"
-#include "unseq_backend_simd.h"
-
-namespace __pstl {
-namespace __internal {
-
-// [alg.foreach]
-// for_each_n with no policy
-
-template <class _ForwardIterator, class _Size, class _Function>
-_ForwardIterator __for_each_n_it_serial(_ForwardIterator __first, _Size __n, _Function __f) {
-  for (; __n > 0; ++__first, --__n)
-    __f(__first);
-  return __first;
-}
-
-//------------------------------------------------------------------------
-// walk1 (pseudo)
-//
-// walk1 evaluates f(x) for each dereferenced value x drawn from [first,last)
-//------------------------------------------------------------------------
-template <class _ForwardIterator, class _Function>
-void __brick_walk1(
-    _ForwardIterator __first, _ForwardIterator __last, _Function __f, /*vector=*/std::false_type) noexcept {
-  std::for_each(__first, __last, __f);
-}
-
-template <class _RandomAccessIterator, class _Function>
-void __brick_walk1(_RandomAccessIterator __first,
-                   _RandomAccessIterator __last,
-                   _Function __f,
-                   /*vector=*/std::true_type) noexcept {
-  __unseq_backend::__simd_walk_1(__first, __last - __first, __f);
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Function>
-void __pattern_walk1(
-    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Function __f) noexcept {
-  __internal::__brick_walk1(__first, __last, __f, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Function>
-void __pattern_walk1(__parallel_tag<_IsVector> __tag,
-                     _ExecutionPolicy&& __exec,
-                     _RandomAccessIterator __first,
-                     _RandomAccessIterator __last,
-                     _Function __f) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  __internal::__except_handler([&]() {
-    __par_backend::__parallel_for(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first,
-        __last,
-        [__f](_RandomAccessIterator __i, _RandomAccessIterator __j) {
-          __internal::__brick_walk1(__i, __j, __f, _IsVector{});
-        });
-  });
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Brick>
-void __pattern_walk_brick(
-    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Brick __brick) noexcept {
-  __brick(__first, __last);
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Brick>
-void __pattern_walk_brick(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _Brick __brick) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  __internal::__except_handler([&]() {
-    __par_backend::__parallel_for(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first,
-        __last,
-        [__brick](_RandomAccessIterator __i, _RandomAccessIterator __j) { __brick(__i, __j); });
-  });
-}
-
-//------------------------------------------------------------------------
-// walk1_n
-//------------------------------------------------------------------------
-template <class _ForwardIterator, class _Size, class _Function>
-_ForwardIterator __brick_walk1_n(_ForwardIterator __first, _Size __n, _Function __f, /*_IsVectorTag=*/std::false_type) {
-  return __internal::__for_each_n_it_serial(__first, __n, [&__f](_ForwardIterator __it) {
-    __f(*__it);
-  }); // calling serial version
-}
-
-template <class _RandomAccessIterator, class _DifferenceType, class _Function>
-_RandomAccessIterator
-__brick_walk1_n(_RandomAccessIterator __first,
-                _DifferenceType __n,
-                _Function __f,
-                /*vectorTag=*/std::true_type) noexcept {
-  return __unseq_backend::__simd_walk_1(__first, __n, __f);
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Size, class _Function>
-_ForwardIterator
-__pattern_walk1_n(_Tag, _ExecutionPolicy&&, _ForwardIterator __first, _Size __n, _Function __f) noexcept {
-  return __internal::__brick_walk1_n(__first, __n, __f, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Size, class _Function>
-_RandomAccessIterator __pattern_walk1_n(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _Size __n,
-    _Function __f) {
-  __internal::__pattern_walk1(__tag, std::forward<_ExecutionPolicy>(__exec), __first, __first + __n, __f);
-
-  return __first + __n;
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Size, class _Brick>
-_ForwardIterator
-__pattern_walk_brick_n(_Tag, _ExecutionPolicy&&, _ForwardIterator __first, _Size __n, _Brick __brick) noexcept {
-  return __brick(__first, __n);
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Size, class _Brick>
-_RandomAccessIterator __pattern_walk_brick_n(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _Size __n,
-    _Brick __brick) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  return __internal::__except_handler([&]() {
-    __par_backend::__parallel_for(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first,
-        __first + __n,
-        [__brick](_RandomAccessIterator __i, _RandomAccessIterator __j) { __brick(__i, __j - __i); });
-    return __first + __n;
-  });
-}
-
-//------------------------------------------------------------------------
-// walk2 (pseudo)
-//
-// walk2 evaluates f(x,y) for deferenced values (x,y) drawn from [first1,last1) and [first2,...)
-//------------------------------------------------------------------------
-template <class _ForwardIterator1, class _ForwardIterator2, class _Function>
-_ForwardIterator2
-__brick_walk2(_ForwardIterator1 __first1,
-              _ForwardIterator1 __last1,
-              _ForwardIterator2 __first2,
-              _Function __f,
-              /*vector=*/std::false_type) noexcept {
-  for (; __first1 != __last1; ++__first1, ++__first2)
-    __f(*__first1, *__first2);
-  return __first2;
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _Function>
-_RandomAccessIterator2
-__brick_walk2(_RandomAccessIterator1 __first1,
-              _RandomAccessIterator1 __last1,
-              _RandomAccessIterator2 __first2,
-              _Function __f,
-              /*vector=*/std::true_type) noexcept {
-  return __unseq_backend::__simd_walk_2(__first1, __last1 - __first1, __first2, __f);
-}
-
-template <class _ForwardIterator1, class _Size, class _ForwardIterator2, class _Function>
-_ForwardIterator2 __brick_walk2_n(
-    _ForwardIterator1 __first1,
-    _Size __n,
-    _ForwardIterator2 __first2,
-    _Function __f,
-    /*vector=*/std::false_type) noexcept {
-  for (; __n > 0; --__n, ++__first1, ++__first2)
-    __f(*__first1, *__first2);
-  return __first2;
-}
-
-template <class _RandomAccessIterator1, class _Size, class _RandomAccessIterator2, class _Function>
-_RandomAccessIterator2 __brick_walk2_n(
-    _RandomAccessIterator1 __first1,
-    _Size __n,
-    _RandomAccessIterator2 __first2,
-    _Function __f,
-    /*vector=*/std::true_type) noexcept {
-  return __unseq_backend::__simd_walk_2(__first1, __n, __first2, __f);
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Function>
-_ForwardIterator2 __pattern_walk2(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _Function __f) noexcept {
-  return __internal::__brick_walk2(__first1, __last1, __first2, __f, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _Function>
-_RandomAccessIterator2 __pattern_walk2(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first1,
-    _RandomAccessIterator1 __last1,
-    _RandomAccessIterator2 __first2,
-    _Function __f) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  return __internal::__except_handler([&]() {
-    __par_backend::__parallel_for(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first1,
-        __last1,
-        [__f, __first1, __first2](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
-          __internal::__brick_walk2(__i, __j, __first2 + (__i - __first1), __f, _IsVector{});
-        });
-    return __first2 + (__last1 - __first1);
-  });
-}
-
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _Size,
-          class _ForwardIterator2,
-          class _Function>
-_ForwardIterator2 __pattern_walk2_n(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1 __first1,
-    _Size __n,
-    _ForwardIterator2 __first2,
-    _Function __f) noexcept {
-  return __internal::__brick_walk2_n(__first1, __n, __first2, __f, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _Size,
-          class _RandomAccessIterator2,
-          class _Function>
-_RandomAccessIterator2 __pattern_walk2_n(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first1,
-    _Size __n,
-    _RandomAccessIterator2 __first2,
-    _Function __f) {
-  return __internal::__pattern_walk2(
-      __tag, std::forward<_ExecutionPolicy>(__exec), __first1, __first1 + __n, __first2, __f);
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Brick>
-_ForwardIterator2 __pattern_walk2_brick(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _Brick __brick) noexcept {
-  return __brick(__first1, __last1, __first2);
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _Brick>
-_RandomAccessIterator2 __pattern_walk2_brick(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first1,
-    _RandomAccessIterator1 __last1,
-    _RandomAccessIterator2 __first2,
-    _Brick __brick) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  return __internal::__except_handler([&]() {
-    __par_backend::__parallel_for(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first1,
-        __last1,
-        [__first1, __first2, __brick](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
-          __brick(__i, __j, __first2 + (__i - __first1));
-        });
-    return __first2 + (__last1 - __first1);
-  });
-}
-
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _Size,
-          class _ForwardIterator2,
-          class _Brick>
-_ForwardIterator2 __pattern_walk2_brick_n(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1 __first1,
-    _Size __n,
-    _ForwardIterator2 __first2,
-    _Brick __brick) noexcept {
-  return __brick(__first1, __n, __first2);
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _Size,
-          class _RandomAccessIterator2,
-          class _Brick>
-_RandomAccessIterator2 __pattern_walk2_brick_n(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first1,
-    _Size __n,
-    _RandomAccessIterator2 __first2,
-    _Brick __brick) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  return __internal::__except_handler([&]() {
-    __par_backend::__parallel_for(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first1,
-        __first1 + __n,
-        [__first1, __first2, __brick](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
-          __brick(__i, __j - __i, __first2 + (__i - __first1));
-        });
-    return __first2 + __n;
-  });
-}
-
-//------------------------------------------------------------------------
-// walk3 (pseudo)
-//
-// walk3 evaluates f(x,y,z) for (x,y,z) drawn from [first1,last1), [first2,...), [first3,...)
-//------------------------------------------------------------------------
-template <class _ForwardIterator1, class _ForwardIterator2, class _ForwardIterator3, class _Function>
-_ForwardIterator3 __brick_walk3(
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator3 __first3,
-    _Function __f,
-    /*vector=*/std::false_type) noexcept {
-  for (; __first1 != __last1; ++__first1, ++__first2, ++__first3)
-    __f(*__first1, *__first2, *__first3);
-  return __first3;
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _RandomAccessIterator3, class _Function>
-_RandomAccessIterator3 __brick_walk3(
-    _RandomAccessIterator1 __first1,
-    _RandomAccessIterator1 __last1,
-    _RandomAccessIterator2 __first2,
-    _RandomAccessIterator3 __first3,
-    _Function __f,
-    /*vector=*/std::true_type) noexcept {
-  return __unseq_backend::__simd_walk_3(__first1, __last1 - __first1, __first2, __first3, __f);
-}
-
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _ForwardIterator3,
-          class _Function>
-_ForwardIterator3 __pattern_walk3(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator3 __first3,
-    _Function __f) noexcept {
-  return __internal::__brick_walk3(__first1, __last1, __first2, __first3, __f, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _RandomAccessIterator3,
-          class _Function>
-_RandomAccessIterator3 __pattern_walk3(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first1,
-    _RandomAccessIterator1 __last1,
-    _RandomAccessIterator2 __first2,
-    _RandomAccessIterator3 __first3,
-    _Function __f) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  return __internal::__except_handler([&]() {
-    __par_backend::__parallel_for(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first1,
-        __last1,
-        [__f, __first1, __first2, __first3](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
-          __internal::__brick_walk3(
-              __i, __j, __first2 + (__i - __first1), __first3 + (__i - __first1), __f, _IsVector{});
-        });
-    return __first3 + (__last1 - __first1);
-  });
-}
-
-//------------------------------------------------------------------------
-// equal
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-bool __brick_equal(_ForwardIterator1 __first1,
-                   _ForwardIterator1 __last1,
-                   _ForwardIterator2 __first2,
-                   _ForwardIterator2 __last2,
-                   _BinaryPredicate __p,
-                   /* IsVector = */ std::false_type) noexcept {
-  return std::equal(__first1, __last1, __first2, __last2, __p);
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
-bool __brick_equal(_RandomAccessIterator1 __first1,
-                   _RandomAccessIterator1 __last1,
-                   _RandomAccessIterator2 __first2,
-                   _RandomAccessIterator2 __last2,
-                   _BinaryPredicate __p,
-                   /* is_vector = */ std::true_type) noexcept {
-  if (__last1 - __first1 != __last2 - __first2)
-    return false;
-
-  return __unseq_backend::__simd_first(__first1, __last1 - __first1, __first2, std::not_fn(__p)).first == __last1;
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-bool __pattern_equal(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _BinaryPredicate __p) noexcept {
-  return __internal::__brick_equal(__first1, __last1, __first2, __last2, __p, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _BinaryPredicate>
-bool __pattern_equal(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first1,
-    _RandomAccessIterator1 __last1,
-    _RandomAccessIterator2 __first2,
-    _RandomAccessIterator2 __last2,
-    _BinaryPredicate __p) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  if (__last1 - __first1 != __last2 - __first2)
-    return false;
-
-  return __internal::__except_handler([&]() {
-    return !__internal::__parallel_or(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first1,
-        __last1,
-        [__first1, __first2, __p](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
-          return !__internal::__brick_equal(
-              __i, __j, __first2 + (__i - __first1), __first2 + (__j - __first1), __p, _IsVector{});
-        });
-  });
-}
-
-//------------------------------------------------------------------------
-// equal version for sequences with equal length
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-bool __brick_equal(_ForwardIterator1 __first1,
-                   _ForwardIterator1 __last1,
-                   _ForwardIterator2 __first2,
-                   _BinaryPredicate __p,
-                   /* IsVector = */ std::false_type) noexcept {
-  return std::equal(__first1, __last1, __first2, __p);
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
-bool __brick_equal(_RandomAccessIterator1 __first1,
-                   _RandomAccessIterator1 __last1,
-                   _RandomAccessIterator2 __first2,
-                   _BinaryPredicate __p,
-                   /* is_vector = */ std::true_type) noexcept {
-  return __unseq_backend::__simd_first(__first1, __last1 - __first1, __first2, std::not_fn(__p)).first == __last1;
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-bool __pattern_equal(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _BinaryPredicate __p) noexcept {
-  return __internal::__brick_equal(__first1, __last1, __first2, __p, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _BinaryPredicate>
-bool __pattern_equal(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first1,
-    _RandomAccessIterator1 __last1,
-    _RandomAccessIterator2 __first2,
-    _BinaryPredicate __p) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  return __internal::__except_handler([&]() {
-    return !__internal::__parallel_or(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first1,
-        __last1,
-        [__first1, __first2, __p](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
-          return !__internal::__brick_equal(__i, __j, __first2 + (__i - __first1), __p, _IsVector{});
-        });
-  });
-}
-
-//------------------------------------------------------------------------
-// find_end
-//------------------------------------------------------------------------
-
-// find the first occurrence of the subsequence [s_first, s_last)
-//   or the  last occurrence of the subsequence in the range [first, last)
-// b_first determines what occurrence we want to find (first or last)
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate, class _IsVector>
-_RandomAccessIterator1 __find_subrange(
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator1 __global_last,
-    _RandomAccessIterator2 __s_first,
-    _RandomAccessIterator2 __s_last,
-    _BinaryPredicate __pred,
-    bool __b_first,
-    _IsVector __is_vector) noexcept {
-  typedef typename std::iterator_traits<_RandomAccessIterator2>::value_type _ValueType;
-  auto __n2 = __s_last - __s_first;
-  if (__n2 < 1) {
-    return __b_first ? __first : __last;
-  }
-
-  auto __n1 = __global_last - __first;
-  if (__n1 < __n2) {
-    return __last;
-  }
-
-  auto __cur = __last;
-  while (__first != __last && (__global_last - __first >= __n2)) {
-    // find position of *s_first in [first, last) (it can be start of subsequence)
-    __first = __internal::__brick_find_if(
-        __first, __last, __equal_value_by_pred<_ValueType, _BinaryPredicate>(*__s_first, __pred), __is_vector);
-
-    // if position that was found previously is the start of subsequence
-    // then we can exit the loop (b_first == true) or keep the position
-    // (b_first == false)
-    if (__first != __last && (__global_last - __first >= __n2) &&
-        __internal::__brick_equal(__s_first + 1, __s_last, __first + 1, __pred, __is_vector)) {
-      if (__b_first) {
-        return __first;
-      } else {
-        __cur = __first;
-      }
-    } else if (__first == __last) {
-      break;
-    } else {
-    }
-
-    // in case of b_first == false we try to find new start position
-    // for the next subsequence
-    ++__first;
-  }
-  return __cur;
-}
-
-template <class _RandomAccessIterator, class _Size, class _Tp, class _BinaryPredicate, class _IsVector>
-_RandomAccessIterator __find_subrange(
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _RandomAccessIterator __global_last,
-    _Size __count,
-    const _Tp& __value,
-    _BinaryPredicate __pred,
-    _IsVector __is_vector) noexcept {
-  if (static_cast<_Size>(__global_last - __first) < __count || __count < 1) {
-    return __last; // According to the standard last shall be returned when count < 1
-  }
-
-  auto __unary_pred = __equal_value_by_pred<_Tp, _BinaryPredicate>(__value, __pred);
-  while (__first != __last && (static_cast<_Size>(__global_last - __first) >= __count)) {
-    __first = __internal::__brick_find_if(__first, __last, __unary_pred, __is_vector);
-
-    // check that all of elements in [first+1, first+count) equal to value
-    if (__first != __last && (static_cast<_Size>(__global_last - __first) >= __count) &&
-        !__internal::__brick_any_of(__first + 1, __first + __count, std::not_fn(__unary_pred), __is_vector)) {
-      return __first;
-    } else if (__first == __last) {
-      break;
-    } else {
-      ++__first;
-    }
-  }
-  return __last;
-}
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-_ForwardIterator1 __brick_find_end(
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __s_first,
-    _ForwardIterator2 __s_last,
-    _BinaryPredicate __pred,
-    /*__is_vector=*/std::false_type) noexcept {
-  return std::find_end(__first, __last, __s_first, __s_last, __pred);
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
-_RandomAccessIterator1 __brick_find_end(
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __s_first,
-    _RandomAccessIterator2 __s_last,
-    _BinaryPredicate __pred,
-    /*__is_vector=*/std::true_type) noexcept {
-  return __find_subrange(__first, __last, __last, __s_first, __s_last, __pred, false, std::true_type());
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-_ForwardIterator1 __pattern_find_end(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __s_first,
-    _ForwardIterator2 __s_last,
-    _BinaryPredicate __pred) noexcept {
-  return __internal::__brick_find_end(__first, __last, __s_first, __s_last, __pred, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _BinaryPredicate>
-_RandomAccessIterator1 __pattern_find_end(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __s_first,
-    _RandomAccessIterator2 __s_last,
-    _BinaryPredicate __pred) noexcept {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  if (__last - __first == __s_last - __s_first) {
-    const bool __res =
-        __internal::__pattern_equal(__tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __s_first, __pred);
-    return __res ? __first : __last;
-  } else {
-    return __internal::__except_handler([&]() {
-      return __internal::__parallel_find(
-          __backend_tag{},
-          std::forward<_ExecutionPolicy>(__exec),
-          __first,
-          __last,
-          [__last, __s_first, __s_last, __pred](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
-            return __internal::__find_subrange(__i, __j, __last, __s_first, __s_last, __pred, false, _IsVector{});
-          },
-          std::greater<typename std::iterator_traits<_RandomAccessIterator1>::
diff erence_type>(),
-          /*is_first=*/false);
-    });
-  }
-}
-
-//------------------------------------------------------------------------
-// find_first_of
-//------------------------------------------------------------------------
-template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-_ForwardIterator1 __brick_find_first_of(
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __s_first,
-    _ForwardIterator2 __s_last,
-    _BinaryPredicate __pred,
-    /*__is_vector=*/std::false_type) noexcept {
-  return std::find_first_of(__first, __last, __s_first, __s_last, __pred);
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
-_RandomAccessIterator1 __brick_find_first_of(
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __s_first,
-    _RandomAccessIterator2 __s_last,
-    _BinaryPredicate __pred,
-    /*__is_vector=*/std::true_type) noexcept {
-  return __unseq_backend::__simd_find_first_of(__first, __last, __s_first, __s_last, __pred);
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-_ForwardIterator1 __pattern_find_first_of(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __s_first,
-    _ForwardIterator2 __s_last,
-    _BinaryPredicate __pred) noexcept {
-  return __internal::__brick_find_first_of(__first, __last, __s_first, __s_last, __pred, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _BinaryPredicate>
-_RandomAccessIterator1 __pattern_find_first_of(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __s_first,
-    _RandomAccessIterator2 __s_last,
-    _BinaryPredicate __pred) noexcept {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  return __internal::__except_handler([&]() {
-    return __internal::__parallel_find(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first,
-        __last,
-        [__s_first, __s_last, __pred](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
-          return __internal::__brick_find_first_of(__i, __j, __s_first, __s_last, __pred, _IsVector{});
-        },
-        std::less<typename std::iterator_traits<_RandomAccessIterator1>::
diff erence_type>(),
-        /*is_first=*/true);
-  });
-}
-
-//------------------------------------------------------------------------
-// search
-//------------------------------------------------------------------------
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
-_RandomAccessIterator1 __brick_search(
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __s_first,
-    _RandomAccessIterator2 __s_last,
-    _BinaryPredicate __pred,
-    /*vector=*/std::false_type) noexcept {
-  return std::search(__first, __last, __s_first, __s_last, __pred);
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
-_RandomAccessIterator1 __brick_search(
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __s_first,
-    _RandomAccessIterator2 __s_last,
-    _BinaryPredicate __pred,
-    /*vector=*/std::true_type) noexcept {
-  return __internal::__find_subrange(__first, __last, __last, __s_first, __s_last, __pred, true, std::true_type());
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-_ForwardIterator1 __pattern_search(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __s_first,
-    _ForwardIterator2 __s_last,
-    _BinaryPredicate __pred) noexcept {
-  return __internal::__brick_search(__first, __last, __s_first, __s_last, __pred, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _BinaryPredicate>
-_RandomAccessIterator1 __pattern_search(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __s_first,
-    _RandomAccessIterator2 __s_last,
-    _BinaryPredicate __pred) noexcept {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  if (__last - __first == __s_last - __s_first) {
-    const bool __res =
-        __internal::__pattern_equal(__tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __s_first, __pred);
-    return __res ? __first : __last;
-  } else {
-    return __internal::__except_handler([&]() {
-      return __internal::__parallel_find(
-          __backend_tag{},
-          std::forward<_ExecutionPolicy>(__exec),
-          __first,
-          __last,
-          [__last, __s_first, __s_last, __pred](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
-            return __internal::__find_subrange(__i, __j, __last, __s_first, __s_last, __pred, true, _IsVector{});
-          },
-          std::less<typename std::iterator_traits<_RandomAccessIterator1>::
diff erence_type>(),
-          /*is_first=*/true);
-    });
-  }
-}
-
-//------------------------------------------------------------------------
-// search_n
-//------------------------------------------------------------------------
-template <class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate>
-_ForwardIterator __brick_search_n(
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _Size __count,
-    const _Tp& __value,
-    _BinaryPredicate __pred,
-    /*vector=*/std::false_type) noexcept {
-  return std::search_n(__first, __last, __count, __value, __pred);
-}
-
-template <class _RandomAccessIterator, class _Size, class _Tp, class _BinaryPredicate>
-_RandomAccessIterator __brick_search_n(
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _Size __count,
-    const _Tp& __value,
-    _BinaryPredicate __pred,
-    /*vector=*/std::true_type) noexcept {
-  return __internal::__find_subrange(__first, __last, __last, __count, __value, __pred, std::true_type());
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate>
-_ForwardIterator __pattern_search_n(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _Size __count,
-    const _Tp& __value,
-    _BinaryPredicate __pred) noexcept {
-  return __internal::__brick_search_n(__first, __last, __count, __value, __pred, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator,
-          class _Size,
-          class _Tp,
-          class _BinaryPredicate>
-_RandomAccessIterator __pattern_search_n(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _Size __count,
-    const _Tp& __value,
-    _BinaryPredicate __pred) noexcept {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  if (static_cast<_Size>(__last - __first) == __count) {
-    const bool __result = !__internal::__pattern_any_of(
-        __tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, [&__value, &__pred](const _Tp& __val) {
-          return !__pred(__val, __value);
-        });
-    return __result ? __first : __last;
-  } else {
-    return __internal::__except_handler([&__exec, __first, __last, __count, &__value, __pred]() {
-      return __internal::__parallel_find(
-          __backend_tag{},
-          std::forward<_ExecutionPolicy>(__exec),
-          __first,
-          __last,
-          [__last, __count, &__value, __pred](_RandomAccessIterator __i, _RandomAccessIterator __j) {
-            return __internal::__find_subrange(__i, __j, __last, __count, __value, __pred, _IsVector{});
-          },
-          std::less<typename std::iterator_traits<_RandomAccessIterator>::
diff erence_type>(),
-          /*is_first=*/true);
-    });
-  }
-}
-
-//------------------------------------------------------------------------
-// copy_n
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _Size, class _OutputIterator>
-_OutputIterator
-__brick_copy_n(_ForwardIterator __first, _Size __n, _OutputIterator __result, /*vector=*/std::false_type) noexcept {
-  return std::copy_n(__first, __n, __result);
-}
-
-template <class _RandomAccessIterator1, class _Size, class _RandomAccessIterator2>
-_RandomAccessIterator2
-__brick_copy_n(_RandomAccessIterator1 __first,
-               _Size __n,
-               _RandomAccessIterator2 __result,
-               /*vector=*/std::true_type) noexcept {
-  return __unseq_backend::__simd_assign(
-      __first, __n, __result, [](_RandomAccessIterator1 __first, _RandomAccessIterator2 __result) {
-        *__result = *__first;
-      });
-}
-
-//------------------------------------------------------------------------
-// copy
-//------------------------------------------------------------------------
-template <class _ForwardIterator, class _OutputIterator>
-_OutputIterator
-__brick_copy(_ForwardIterator __first,
-             _ForwardIterator __last,
-             _OutputIterator __result,
-             /*vector=*/std::false_type) noexcept {
-  return std::copy(__first, __last, __result);
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2>
-_RandomAccessIterator2
-__brick_copy(_RandomAccessIterator1 __first,
-             _RandomAccessIterator1 __last,
-             _RandomAccessIterator2 __result,
-             /*vector=*/std::true_type) noexcept {
-  return __unseq_backend::__simd_assign(
-      __first, __last - __first, __result, [](_RandomAccessIterator1 __first, _RandomAccessIterator2 __result) {
-        *__result = *__first;
-      });
-}
-
-//------------------------------------------------------------------------
-// move
-//------------------------------------------------------------------------
-template <class _ForwardIterator, class _OutputIterator>
-_OutputIterator
-__brick_move(_ForwardIterator __first,
-             _ForwardIterator __last,
-             _OutputIterator __result,
-             /*vector=*/std::false_type) noexcept {
-  return std::move(__first, __last, __result);
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2>
-_RandomAccessIterator2
-__brick_move(_RandomAccessIterator1 __first,
-             _RandomAccessIterator1 __last,
-             _RandomAccessIterator2 __result,
-             /*vector=*/std::true_type) noexcept {
-  return __unseq_backend::__simd_assign(
-      __first, __last - __first, __result, [](_RandomAccessIterator1 __first, _RandomAccessIterator2 __result) {
-        *__result = std::move(*__first);
-      });
-}
-
-struct __brick_move_destroy {
-  template <typename _RandomAccessIterator1, typename _RandomAccessIterator2>
-  _RandomAccessIterator2
-  operator()(_RandomAccessIterator1 __first,
-             _RandomAccessIterator1 __last,
-             _RandomAccessIterator2 __result,
-             /*vec*/ std::true_type) const {
-    using _IteratorValueType = typename std::iterator_traits<_RandomAccessIterator1>::value_type;
-
-    return __unseq_backend::__simd_assign(
-        __first, __last - __first, __result, [](_RandomAccessIterator1 __first, _RandomAccessIterator2 __result) {
-          *__result = std::move(*__first);
-          (*__first).~_IteratorValueType();
-        });
-  }
-
-  template <typename _RandomAccessIterator1, typename _RandomAccessIterator2>
-  _RandomAccessIterator2
-  operator()(_RandomAccessIterator1 __first,
-             _RandomAccessIterator1 __last,
-             _RandomAccessIterator2 __result,
-             /*vec*/ std::false_type) const {
-    using _IteratorValueType = typename std::iterator_traits<_RandomAccessIterator1>::value_type;
-
-    for (; __first != __last; ++__first, ++__result) {
-      *__result = std::move(*__first);
-      (*__first).~_IteratorValueType();
-    }
-    return __result;
-  }
-};
-
-//------------------------------------------------------------------------
-// swap_ranges
-//------------------------------------------------------------------------
-template <class _ForwardIterator, class _OutputIterator>
-_OutputIterator __brick_swap_ranges(
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _OutputIterator __result,
-    /*vector=*/std::false_type) noexcept {
-  return std::swap_ranges(__first, __last, __result);
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2>
-_RandomAccessIterator2 __brick_swap_ranges(
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __result,
-    /*vector=*/std::true_type) noexcept {
-  using std::iter_swap;
-  return __unseq_backend::__simd_assign(
-      __first, __last - __first, __result, iter_swap<_RandomAccessIterator1, _RandomAccessIterator2>);
-}
-
-//------------------------------------------------------------------------
-// copy_if
-//------------------------------------------------------------------------
-template <class _ForwardIterator, class _OutputIterator, class _UnaryPredicate>
-_OutputIterator __brick_copy_if(
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _OutputIterator __result,
-    _UnaryPredicate __pred,
-    /*vector=*/std::false_type) noexcept {
-  return std::copy_if(__first, __last, __result, __pred);
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _UnaryPredicate>
-_RandomAccessIterator2 __brick_copy_if(
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __result,
-    _UnaryPredicate __pred,
-    /*vector=*/std::true_type) noexcept {
-#if defined(_PSTL_MONOTONIC_PRESENT)
-  return __unseq_backend::__simd_copy_if(__first, __last - __first, __result, __pred);
-#else
-  return std::copy_if(__first, __last, __result, __pred);
-#endif
-}
-
-// TODO: Try to use transform_reduce for combining __brick_copy_if_phase1 on IsVector.
-template <class _DifferenceType, class _ForwardIterator, class _UnaryPredicate>
-std::pair<_DifferenceType, _DifferenceType> __brick_calc_mask_1(
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    bool* __restrict __mask,
-    _UnaryPredicate __pred,
-    /*vector=*/std::false_type) noexcept {
-  auto __count_true = _DifferenceType(0);
-  auto __size       = __last - __first;
-
-  static_assert(__are_random_access_iterators<_ForwardIterator>::value,
-                "Pattern-brick error. Should be a random access iterator.");
-
-  for (; __first != __last; ++__first, ++__mask) {
-    *__mask = __pred(*__first);
-    if (*__mask) {
-      ++__count_true;
-    }
-  }
-  return std::make_pair(__count_true, __size - __count_true);
-}
-
-template <class _DifferenceType, class _RandomAccessIterator, class _UnaryPredicate>
-std::pair<_DifferenceType, _DifferenceType> __brick_calc_mask_1(
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    bool* __mask,
-    _UnaryPredicate __pred,
-    /*vector=*/std::true_type) noexcept {
-  auto __result = __unseq_backend::__simd_calc_mask_1(__first, __last - __first, __mask, __pred);
-  return std::make_pair(__result, (__last - __first) - __result);
-}
-
-template <class _ForwardIterator, class _OutputIterator, class _Assigner>
-void __brick_copy_by_mask(
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _OutputIterator __result,
-    bool* __mask,
-    _Assigner __assigner,
-    /*vector=*/std::false_type) noexcept {
-  for (; __first != __last; ++__first, ++__mask) {
-    if (*__mask) {
-      __assigner(__first, __result);
-      ++__result;
-    }
-  }
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _Assigner>
-void __brick_copy_by_mask(
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __result,
-    bool* __restrict __mask,
-    _Assigner __assigner,
-    /*vector=*/std::true_type) noexcept {
-#if defined(_PSTL_MONOTONIC_PRESENT)
-  __unseq_backend::__simd_copy_by_mask(__first, __last - __first, __result, __mask, __assigner);
-#else
-  __internal::__brick_copy_by_mask(__first, __last, __result, __mask, __assigner, std::false_type());
-#endif
-}
-
-template <class _ForwardIterator, class _OutputIterator1, class _OutputIterator2>
-void __brick_partition_by_mask(
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _OutputIterator1 __out_true,
-    _OutputIterator2 __out_false,
-    bool* __mask,
-    /*vector=*/std::false_type) noexcept {
-  for (; __first != __last; ++__first, ++__mask) {
-    if (*__mask) {
-      *__out_true = *__first;
-      ++__out_true;
-    } else {
-      *__out_false = *__first;
-      ++__out_false;
-    }
-  }
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _RandomAccessIterator3>
-void __brick_partition_by_mask(
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __out_true,
-    _RandomAccessIterator3 __out_false,
-    bool* __mask,
-    /*vector=*/std::true_type) noexcept {
-#if defined(_PSTL_MONOTONIC_PRESENT)
-  __unseq_backend::__simd_partition_by_mask(__first, __last - __first, __out_true, __out_false, __mask);
-#else
-  __internal::__brick_partition_by_mask(__first, __last, __out_true, __out_false, __mask, std::false_type());
-#endif
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _OutputIterator, class _UnaryPredicate>
-_OutputIterator __pattern_copy_if(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _OutputIterator __result,
-    _UnaryPredicate __pred) noexcept {
-  return __internal::__brick_copy_if(__first, __last, __result, __pred, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _UnaryPredicate>
-_RandomAccessIterator2 __pattern_copy_if(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __result,
-    _UnaryPredicate __pred) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  typedef typename std::iterator_traits<_RandomAccessIterator1>::
diff erence_type _DifferenceType;
-  const _DifferenceType __n = __last - __first;
-  if (_DifferenceType(1) < __n) {
-    __par_backend::__buffer<bool> __mask_buf(__n);
-    return __internal::__except_handler([&__exec, __n, __first, __result, __pred, &__mask_buf]() {
-      bool* __mask = __mask_buf.get();
-      _DifferenceType __m{};
-      __par_backend::__parallel_strict_scan(
-          __backend_tag{},
-          std::forward<_ExecutionPolicy>(__exec),
-          __n,
-          _DifferenceType(0),
-          [=](_DifferenceType __i, _DifferenceType __len) { // Reduce
-            return __internal::__brick_calc_mask_1<_DifferenceType>(
-                       __first + __i, __first + (__i + __len), __mask + __i, __pred, _IsVector{})
-                .first;
-          },
-          std::plus<_DifferenceType>(),                                                // Combine
-          [=](_DifferenceType __i, _DifferenceType __len, _DifferenceType __initial) { // Scan
-            __internal::__brick_copy_by_mask(
-                __first + __i,
-                __first + (__i + __len),
-                __result + __initial,
-                __mask + __i,
-                [](_RandomAccessIterator1 __x, _RandomAccessIterator2 __z) { *__z = *__x; },
-                _IsVector{});
-          },
-          [&__m](_DifferenceType __total) { __m = __total; });
-      return __result + __m;
-    });
-  }
-  // trivial sequence - use serial algorithm
-  return __internal::__brick_copy_if(__first, __last, __result, __pred, _IsVector{});
-}
-
-//------------------------------------------------------------------------
-// count
-//------------------------------------------------------------------------
-template <class _RandomAccessIterator, class _Predicate>
-typename std::iterator_traits<_RandomAccessIterator>::
diff erence_type
-__brick_count(_RandomAccessIterator __first,
-              _RandomAccessIterator __last,
-              _Predicate __pred,
-              /* is_vector = */ std::true_type) noexcept {
-  return __unseq_backend::__simd_count(__first, __last - __first, __pred);
-}
-
-template <class _ForwardIterator, class _Predicate>
-typename std::iterator_traits<_ForwardIterator>::
diff erence_type
-__brick_count(_ForwardIterator __first,
-              _ForwardIterator __last,
-              _Predicate __pred,
-              /* is_vector = */ std::false_type) noexcept {
-  return std::count_if(__first, __last, __pred);
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Predicate>
-typename std::iterator_traits<_ForwardIterator>::
diff erence_type __pattern_count(
-    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Predicate __pred) noexcept {
-  return __internal::__brick_count(__first, __last, __pred, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Predicate>
-typename std::iterator_traits<_RandomAccessIterator>::
diff erence_type __pattern_count(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _Predicate __pred) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  typedef typename std::iterator_traits<_RandomAccessIterator>::
diff erence_type _SizeType;
-  return __internal::__except_handler([&]() {
-    return __par_backend::__parallel_reduce(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first,
-        __last,
-        _SizeType(0),
-        [__pred](_RandomAccessIterator __begin, _RandomAccessIterator __end, _SizeType __value) -> _SizeType {
-          return __value + __internal::__brick_count(__begin, __end, __pred, _IsVector{});
-        },
-        std::plus<_SizeType>());
-  });
-}
-
-//------------------------------------------------------------------------
-// unique
-//------------------------------------------------------------------------
-
-template <class _RandomAccessIterator, class _BinaryPredicate>
-_RandomAccessIterator
-__brick_unique(_RandomAccessIterator __first,
-               _RandomAccessIterator __last,
-               _BinaryPredicate __pred,
-               /*is_vector=*/std::false_type) noexcept {
-  return std::unique(__first, __last, __pred);
-}
-
-template <class _RandomAccessIterator, class _BinaryPredicate>
-_RandomAccessIterator
-__brick_unique(_RandomAccessIterator __first,
-               _RandomAccessIterator __last,
-               _BinaryPredicate __pred,
-               /*is_vector=*/std::true_type) noexcept {
-  // TODO: vectorize
-  return std::unique(__first, __last, __pred);
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _BinaryPredicate>
-_ForwardIterator __pattern_unique(
-    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred) noexcept {
-  return __internal::__brick_unique(__first, __last, __pred, typename _Tag::__is_vector{});
-}
-
-// That function is shared between two algorithms - remove_if (__pattern_remove_if) and unique (pattern unique). But a
-// mask calculation is 
diff erent. So, a caller passes _CalcMask brick into remove_elements.
-template <class _IsVector, class _ExecutionPolicy, class _ForwardIterator, class _CalcMask>
-_ForwardIterator __remove_elements(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _CalcMask __calc_mask) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  typedef typename std::iterator_traits<_ForwardIterator>::
diff erence_type _DifferenceType;
-  typedef typename std::iterator_traits<_ForwardIterator>::value_type _Tp;
-  _DifferenceType __n = __last - __first;
-  __par_backend::__buffer<bool> __mask_buf(__n);
-  // 1. find a first iterator that should be removed
-  return __internal::__except_handler([&]() {
-    bool* __mask          = __mask_buf.get();
-    _DifferenceType __min = __par_backend::__parallel_reduce(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        _DifferenceType(0),
-        __n,
-        __n,
-        [__first, __mask, &__calc_mask](
-            _DifferenceType __i, _DifferenceType __j, _DifferenceType __local_min) -> _DifferenceType {
-          // Create mask
-          __calc_mask(__mask + __i, __mask + __j, __first + __i);
-
-          // if minimum was found in a previous range we shouldn't do anymore
-          if (__local_min < __i) {
-            return __local_min;
-          }
-          // find first iterator that should be removed
-          bool* __result = __internal::__brick_find_if(
-              __mask + __i, __mask + __j, [](bool __val) { return !__val; }, _IsVector{});
-          if (__result - __mask == __j) {
-            return __local_min;
-          }
-          return std::min(__local_min, _DifferenceType(__result - __mask));
-        },
-        [](_DifferenceType __local_min1, _DifferenceType __local_min2) -> _DifferenceType {
-          return std::min(__local_min1, __local_min2);
-        });
-
-    // No elements to remove - exit
-    if (__min == __n) {
-      return __last;
-    }
-    __n -= __min;
-    __first += __min;
-
-    __par_backend::__buffer<_Tp> __buf(__n);
-    _Tp* __result = __buf.get();
-    __mask += __min;
-    _DifferenceType __m{};
-    // 2. Elements that doesn't satisfy pred are moved to result
-    __par_backend::__parallel_strict_scan(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __n,
-        _DifferenceType(0),
-        [__mask](_DifferenceType __i, _DifferenceType __len) {
-          return __internal::__brick_count(
-              __mask + __i, __mask + __i + __len, [](bool __val) { return __val; }, _IsVector{});
-        },
-        std::plus<_DifferenceType>(),
-        [=](_DifferenceType __i, _DifferenceType __len, _DifferenceType __initial) {
-          __internal::__brick_copy_by_mask(
-              __first + __i,
-              __first + __i + __len,
-              __result + __initial,
-              __mask + __i,
-              [](_ForwardIterator __x, _Tp* __z) {
-                __internal::__invoke_if_else(
-                    std::is_trivial<_Tp>(),
-                    [&]() { *__z = std::move(*__x); },
-                    [&]() { ::new (std::addressof(*__z)) _Tp(std::move(*__x)); });
-              },
-              _IsVector{});
-        },
-        [&__m](_DifferenceType __total) { __m = __total; });
-
-    // 3. Elements from result are moved to [first, last)
-    __par_backend::__parallel_for(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __result,
-        __result + __m,
-        [__result, __first](_Tp* __i, _Tp* __j) {
-          __invoke_if_else(
-              std::is_trivial<_Tp>(),
-              [&]() { __brick_move(__i, __j, __first + (__i - __result), _IsVector{}); },
-              [&]() { __brick_move_destroy()(__i, __j, __first + (__i - __result), _IsVector{}); });
-        });
-    return __first + __m;
-  });
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _BinaryPredicate>
-_RandomAccessIterator __pattern_unique(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _BinaryPredicate __pred) noexcept {
-  typedef typename std::iterator_traits<_RandomAccessIterator>::reference _ReferenceType;
-
-  if (__first == __last) {
-    return __last;
-  }
-  if (__first + 1 == __last || __first + 2 == __last) {
-    // Trivial sequence - use serial algorithm
-    return __internal::__brick_unique(__first, __last, __pred, _IsVector{});
-  }
-  return __internal::__remove_elements(
-      __tag,
-      std::forward<_ExecutionPolicy>(__exec),
-      ++__first,
-      __last,
-      [&__pred](bool* __b, bool* __e, _RandomAccessIterator __it) {
-        __internal::__brick_walk3(
-            __b,
-            __e,
-            __it - 1,
-            __it,
-            [&__pred](bool& __x, _ReferenceType __y, _ReferenceType __z) { __x = !__pred(__y, __z); },
-            _IsVector{});
-      });
-}
-
-//------------------------------------------------------------------------
-// unique_copy
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class OutputIterator, class _BinaryPredicate>
-OutputIterator __brick_unique_copy(
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    OutputIterator __result,
-    _BinaryPredicate __pred,
-    /*vector=*/std::false_type) noexcept {
-  return std::unique_copy(__first, __last, __result, __pred);
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _BinaryPredicate>
-_RandomAccessIterator2 __brick_unique_copy(
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __result,
-    _BinaryPredicate __pred,
-    /*vector=*/std::true_type) noexcept {
-#if defined(_PSTL_MONOTONIC_PRESENT)
-  return __unseq_backend::__simd_unique_copy(__first, __last - __first, __result, __pred);
-#else
-  return std::unique_copy(__first, __last, __result, __pred);
-#endif
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _OutputIterator, class _BinaryPredicate>
-_OutputIterator __pattern_unique_copy(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _OutputIterator __result,
-    _BinaryPredicate __pred) noexcept {
-  return __internal::__brick_unique_copy(__first, __last, __result, __pred, typename _Tag::__is_vector{});
-}
-
-template <class _DifferenceType, class _RandomAccessIterator, class _BinaryPredicate>
-_DifferenceType __brick_calc_mask_2(
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    bool* __restrict __mask,
-    _BinaryPredicate __pred,
-    /*vector=*/std::false_type) noexcept {
-  _DifferenceType __count = 0;
-  for (; __first != __last; ++__first, ++__mask) {
-    *__mask = !__pred(*__first, *(__first - 1));
-    __count += *__mask;
-  }
-  return __count;
-}
-
-template <class _DifferenceType, class _RandomAccessIterator, class _BinaryPredicate>
-_DifferenceType __brick_calc_mask_2(
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    bool* __restrict __mask,
-    _BinaryPredicate __pred,
-    /*vector=*/std::true_type) noexcept {
-  return __unseq_backend::__simd_calc_mask_2(__first, __last - __first, __mask, __pred);
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _BinaryPredicate>
-_RandomAccessIterator2 __pattern_unique_copy(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __result,
-    _BinaryPredicate __pred) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  typedef typename std::iterator_traits<_RandomAccessIterator1>::
diff erence_type _DifferenceType;
-  const _DifferenceType __n = __last - __first;
-  if (_DifferenceType(2) < __n) {
-    __par_backend::__buffer<bool> __mask_buf(__n);
-    if (_DifferenceType(2) < __n) {
-      return __internal::__except_handler([&__exec, __n, __first, __result, __pred, &__mask_buf]() {
-        bool* __mask = __mask_buf.get();
-        _DifferenceType __m{};
-        __par_backend::__parallel_strict_scan(
-            __backend_tag{},
-            std::forward<_ExecutionPolicy>(__exec),
-            __n,
-            _DifferenceType(0),
-            [=](_DifferenceType __i, _DifferenceType __len) -> _DifferenceType { // Reduce
-              _DifferenceType __extra = 0;
-              if (__i == 0) {
-                // Special boundary case
-                __mask[__i] = true;
-                if (--__len == 0)
-                  return 1;
-                ++__i;
-                ++__extra;
-              }
-              return __internal::__brick_calc_mask_2<_DifferenceType>(
-                         __first + __i, __first + (__i + __len), __mask + __i, __pred, _IsVector{}) +
-                     __extra;
-            },
-            std::plus<_DifferenceType>(),                                                // Combine
-            [=](_DifferenceType __i, _DifferenceType __len, _DifferenceType __initial) { // Scan
-              // Phase 2 is same as for __pattern_copy_if
-              __internal::__brick_copy_by_mask(
-                  __first + __i,
-                  __first + (__i + __len),
-                  __result + __initial,
-                  __mask + __i,
-                  [](_RandomAccessIterator1 __x, _RandomAccessIterator2 __z) { *__z = *__x; },
-                  _IsVector{});
-            },
-            [&__m](_DifferenceType __total) { __m = __total; });
-        return __result + __m;
-      });
-    }
-  }
-  // trivial sequence - use serial algorithm
-  return __internal::__brick_unique_copy(__first, __last, __result, __pred, _IsVector{});
-}
-
-//------------------------------------------------------------------------
-// reverse
-//------------------------------------------------------------------------
-template <class _BidirectionalIterator>
-void __brick_reverse(
-    _BidirectionalIterator __first, _BidirectionalIterator __last, /*__is_vector=*/std::false_type) noexcept {
-  std::reverse(__first, __last);
-}
-
-template <class _RandomAccessIterator>
-void __brick_reverse(
-    _RandomAccessIterator __first, _RandomAccessIterator __last, /*__is_vector=*/std::true_type) noexcept {
-  typedef typename std::iterator_traits<_RandomAccessIterator>::reference _ReferenceType;
-
-  const auto __n = (__last - __first) / 2;
-  __unseq_backend::__simd_walk_2(
-      __first, __n, std::reverse_iterator<_RandomAccessIterator>(__last), [](_ReferenceType __x, _ReferenceType __y) {
-        using std::swap;
-        swap(__x, __y);
-      });
-}
-
-// this brick is called in parallel version, so we can use iterator arithmetic
-template <class _BidirectionalIterator>
-void __brick_reverse(_BidirectionalIterator __first,
-                     _BidirectionalIterator __last,
-                     _BidirectionalIterator __d_last,
-                     /*is_vector=*/std::false_type) noexcept {
-  for (--__d_last; __first != __last; ++__first, --__d_last) {
-    using std::iter_swap;
-    iter_swap(__first, __d_last);
-  }
-}
-
-// this brick is called in parallel version, so we can use iterator arithmetic
-template <class _RandomAccessIterator>
-void __brick_reverse(_RandomAccessIterator __first,
-                     _RandomAccessIterator __last,
-                     _RandomAccessIterator __d_last,
-                     /*is_vector=*/std::true_type) noexcept {
-  typedef typename std::iterator_traits<_RandomAccessIterator>::reference _ReferenceType;
-
-  __unseq_backend::__simd_walk_2(
-      __first,
-      __last - __first,
-      std::reverse_iterator<_RandomAccessIterator>(__d_last),
-      [](_ReferenceType __x, _ReferenceType __y) {
-        using std::swap;
-        swap(__x, __y);
-      });
-}
-
-template <class _Tag, class _ExecutionPolicy, class _BidirectionalIterator>
-void __pattern_reverse(
-    _Tag, _ExecutionPolicy&&, _BidirectionalIterator __first, _BidirectionalIterator __last) noexcept {
-  __internal::__brick_reverse(__first, __last, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator>
-void __pattern_reverse(__parallel_tag<_IsVector> __tag,
-                       _ExecutionPolicy&& __exec,
-                       _RandomAccessIterator __first,
-                       _RandomAccessIterator __last) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  __par_backend::__parallel_for(
-      __backend_tag{},
-      std::forward<_ExecutionPolicy>(__exec),
-      __first,
-      __first + (__last - __first) / 2,
-      [__first, __last](_RandomAccessIterator __inner_first, _RandomAccessIterator __inner_last) {
-        __internal::__brick_reverse(__inner_first, __inner_last, __last - (__inner_first - __first), _IsVector{});
-      });
-}
-
-//------------------------------------------------------------------------
-// reverse_copy
-//------------------------------------------------------------------------
-
-template <class _BidirectionalIterator, class _OutputIterator>
-_OutputIterator __brick_reverse_copy(
-    _BidirectionalIterator __first,
-    _BidirectionalIterator __last,
-    _OutputIterator __d_first,
-    /*is_vector=*/std::false_type) noexcept {
-  return std::reverse_copy(__first, __last, __d_first);
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2>
-_RandomAccessIterator2 __brick_reverse_copy(
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __d_first,
-    /*is_vector=*/std::true_type) noexcept {
-  typedef typename std::iterator_traits<_RandomAccessIterator1>::reference _ReferenceType1;
-  typedef typename std::iterator_traits<_RandomAccessIterator2>::reference _ReferenceType2;
-
-  return __unseq_backend::__simd_walk_2(
-      std::reverse_iterator<_RandomAccessIterator1>(__last),
-      __last - __first,
-      __d_first,
-      [](_ReferenceType1 __x, _ReferenceType2 __y) { __y = __x; });
-}
-
-template <class _Tag, class _ExecutionPolicy, class _BidirectionalIterator, class _OutputIterator>
-_OutputIterator __pattern_reverse_copy(
-    _Tag,
-    _ExecutionPolicy&&,
-    _BidirectionalIterator __first,
-    _BidirectionalIterator __last,
-    _OutputIterator __d_first) noexcept {
-  return __internal::__brick_reverse_copy(__first, __last, __d_first, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator1, class _RandomAccessIterator2>
-_RandomAccessIterator2 __pattern_reverse_copy(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __d_first) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  auto __len = __last - __first;
-  __par_backend::__parallel_for(
-      __backend_tag{},
-      std::forward<_ExecutionPolicy>(__exec),
-      __first,
-      __last,
-      [__first, __len, __d_first](_RandomAccessIterator1 __inner_first, _RandomAccessIterator1 __inner_last) {
-        __internal::__brick_reverse_copy(
-            __inner_first, __inner_last, __d_first + (__len - (__inner_last - __first)), _IsVector{});
-      });
-  return __d_first + __len;
-}
-
-//------------------------------------------------------------------------
-// rotate
-//------------------------------------------------------------------------
-template <class _ForwardIterator>
-_ForwardIterator
-__brick_rotate(_ForwardIterator __first,
-               _ForwardIterator __middle,
-               _ForwardIterator __last,
-               /*is_vector=*/std::false_type) noexcept {
-#if defined(_PSTL_CPP11_STD_ROTATE_BROKEN)
-  std::rotate(__first, __middle, __last);
-  return std::next(__first, std::distance(__middle, __last));
-#else
-  return std::rotate(__first, __middle, __last);
-#endif
-}
-
-template <class _RandomAccessIterator>
-_RandomAccessIterator
-__brick_rotate(_RandomAccessIterator __first,
-               _RandomAccessIterator __middle,
-               _RandomAccessIterator __last,
-               /*is_vector=*/std::true_type) noexcept {
-  auto __n                          = __last - __first;
-  auto __m                          = __middle - __first;
-  const _RandomAccessIterator __ret = __first + (__last - __middle);
-
-  bool __is_left = (__m <= __n / 2);
-  if (!__is_left)
-    __m = __n - __m;
-
-  while (__n > 1 && __m > 0) {
-    using std::iter_swap;
-    const auto __m_2 = __m * 2;
-    if (__is_left) {
-      for (; __last - __first >= __m_2; __first += __m) {
-        __unseq_backend::__simd_assign(
-            __first, __m, __first + __m, iter_swap<_RandomAccessIterator, _RandomAccessIterator>);
-      }
-    } else {
-      for (; __last - __first >= __m_2; __last -= __m) {
-        __unseq_backend::__simd_assign(
-            __last - __m, __m, __last - __m_2, iter_swap<_RandomAccessIterator, _RandomAccessIterator>);
-      }
-    }
-    __is_left = !__is_left;
-    __m       = __n % __m;
-    __n       = __last - __first;
-  }
-
-  return __ret;
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator>
-_ForwardIterator __pattern_rotate(
-    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last) noexcept {
-  return __internal::__brick_rotate(__first, __middle, __last, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator>
-_RandomAccessIterator __pattern_rotate(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __middle,
-    _RandomAccessIterator __last) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  typedef typename std::iterator_traits<_RandomAccessIterator>::value_type _Tp;
-  auto __n = __last - __first;
-  auto __m = __middle - __first;
-  if (__m <= __n / 2) {
-    __par_backend::__buffer<_Tp> __buf(__n - __m);
-    return __internal::__except_handler([&__exec, __n, __m, __first, __middle, __last, &__buf]() {
-      _Tp* __result = __buf.get();
-      __par_backend::__parallel_for(
-          __backend_tag{},
-          std::forward<_ExecutionPolicy>(__exec),
-          __middle,
-          __last,
-          [__middle, __result](_RandomAccessIterator __b, _RandomAccessIterator __e) {
-            __internal::__brick_uninitialized_move(__b, __e, __result + (__b - __middle), _IsVector{});
-          });
-
-      __par_backend::__parallel_for(
-          __backend_tag{},
-          std::forward<_ExecutionPolicy>(__exec),
-          __first,
-          __middle,
-          [__last, __middle](_RandomAccessIterator __b, _RandomAccessIterator __e) {
-            __internal::__brick_move(__b, __e, __b + (__last - __middle), _IsVector{});
-          });
-
-      __par_backend::__parallel_for(
-          __backend_tag{},
-          std::forward<_ExecutionPolicy>(__exec),
-          __result,
-          __result + (__n - __m),
-          [__first, __result](_Tp* __b, _Tp* __e) {
-            __brick_move_destroy()(__b, __e, __first + (__b - __result), _IsVector{});
-          });
-
-      return __first + (__last - __middle);
-    });
-  } else {
-    __par_backend::__buffer<_Tp> __buf(__m);
-    return __internal::__except_handler([&__exec, __n, __m, __first, __middle, __last, &__buf]() {
-      _Tp* __result = __buf.get();
-      __par_backend::__parallel_for(
-          __backend_tag{},
-          std::forward<_ExecutionPolicy>(__exec),
-          __first,
-          __middle,
-          [__first, __result](_RandomAccessIterator __b, _RandomAccessIterator __e) {
-            __internal::__brick_uninitialized_move(__b, __e, __result + (__b - __first), _IsVector{});
-          });
-
-      __par_backend::__parallel_for(
-          __backend_tag{},
-          std::forward<_ExecutionPolicy>(__exec),
-          __middle,
-          __last,
-          [__first, __middle](_RandomAccessIterator __b, _RandomAccessIterator __e) {
-            __internal::__brick_move(__b, __e, __first + (__b - __middle), _IsVector{});
-          });
-
-      __par_backend::__parallel_for(
-          __backend_tag{},
-          std::forward<_ExecutionPolicy>(__exec),
-          __result,
-          __result + __m,
-          [__n, __m, __first, __result](_Tp* __b, _Tp* __e) {
-            __brick_move_destroy()(__b, __e, __first + ((__n - __m) + (__b - __result)), _IsVector{});
-          });
-
-      return __first + (__last - __middle);
-    });
-  }
-}
-
-//------------------------------------------------------------------------
-// rotate_copy
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _OutputIterator>
-_OutputIterator __brick_rotate_copy(
-    _ForwardIterator __first,
-    _ForwardIterator __middle,
-    _ForwardIterator __last,
-    _OutputIterator __result,
-    /*__is_vector=*/std::false_type) noexcept {
-  return std::rotate_copy(__first, __middle, __last, __result);
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2>
-_RandomAccessIterator2 __brick_rotate_copy(
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __middle,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __result,
-    /*__is_vector=*/std::true_type) noexcept {
-  _RandomAccessIterator2 __res = __internal::__brick_copy(__middle, __last, __result, std::true_type());
-  return __internal::__brick_copy(__first, __middle, __res, std::true_type());
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _OutputIterator>
-_OutputIterator __pattern_rotate_copy(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator __first,
-    _ForwardIterator __middle,
-    _ForwardIterator __last,
-    _OutputIterator __result) noexcept {
-  return __internal::__brick_rotate_copy(__first, __middle, __last, __result, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator1, class _RandomAccessIterator2>
-_RandomAccessIterator2 __pattern_rotate_copy(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __middle,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __result) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  __par_backend::__parallel_for(
-      __backend_tag{},
-      std::forward<_ExecutionPolicy>(__exec),
-      __first,
-      __last,
-      [__first, __last, __middle, __result](_RandomAccessIterator1 __b, _RandomAccessIterator1 __e) {
-        if (__b > __middle) {
-          __internal::__brick_copy(__b, __e, __result + (__b - __middle), _IsVector{});
-        } else {
-          _RandomAccessIterator2 __new_result = __result + ((__last - __middle) + (__b - __first));
-          if (__e < __middle) {
-            __internal::__brick_copy(__b, __e, __new_result, _IsVector{});
-          } else {
-            __internal::__brick_copy(__b, __middle, __new_result, _IsVector{});
-            __internal::__brick_copy(__middle, __e, __result, _IsVector{});
-          }
-        }
-      });
-  return __result + (__last - __first);
-}
-
-//------------------------------------------------------------------------
-// is_partitioned
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _UnaryPredicate>
-bool __brick_is_partitioned(_ForwardIterator __first,
-                            _ForwardIterator __last,
-                            _UnaryPredicate __pred,
-                            /*is_vector=*/std::false_type) noexcept {
-  return std::is_partitioned(__first, __last, __pred);
-}
-
-template <class _RandomAccessIterator, class _UnaryPredicate>
-bool __brick_is_partitioned(_RandomAccessIterator __first,
-                            _RandomAccessIterator __last,
-                            _UnaryPredicate __pred,
-                            /*is_vector=*/std::true_type) noexcept {
-  typedef typename std::iterator_traits<_RandomAccessIterator>::
diff erence_type _SizeType;
-  if (__first == __last) {
-    return true;
-  } else {
-    _RandomAccessIterator __result = __unseq_backend::__simd_first(
-        __first, _SizeType(0), __last - __first, [&__pred](_RandomAccessIterator __it, _SizeType __i) {
-          return !__pred(__it[__i]);
-        });
-    if (__result == __last) {
-      return true;
-    } else {
-      ++__result;
-      return !__unseq_backend::__simd_or(__result, __last - __result, __pred);
-    }
-  }
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate>
-bool __pattern_is_partitioned(
-    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _UnaryPredicate __pred) noexcept {
-  return __internal::__brick_is_partitioned(__first, __last, __pred, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _UnaryPredicate>
-bool __pattern_is_partitioned(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _UnaryPredicate __pred) {
-  if (__first == __last) {
-    return true;
-  } else {
-    using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-    return __internal::__except_handler([&]() {
-      // State of current range:
-      // broken     - current range is not partitioned by pred
-      // all_true   - all elements in current range satisfy pred
-      // all_false  - all elements in current range don't satisfy pred
-      // true_false - elements satisfy pred are placed before elements that don't satisfy pred
-      enum _ReduceType { __not_init = -1, __broken, __all_true, __all_false, __true_false };
-      _ReduceType __init = __not_init;
-
-      // Array with states that we'll have when state from the left branch is merged with state from the right branch.
-      // State is calculated by formula: new_state = table[left_state * 4 + right_state]
-      _ReduceType __table[] = {
-          __broken,
-          __broken,
-          __broken,
-          __broken,
-          __broken,
-          __all_true,
-          __true_false,
-          __true_false,
-          __broken,
-          __broken,
-          __all_false,
-          __broken,
-          __broken,
-          __broken,
-          __true_false,
-          __broken};
-
-      __init = __par_backend::__parallel_reduce(
-          __backend_tag{},
-          std::forward<_ExecutionPolicy>(__exec),
-          __first,
-          __last,
-          __init,
-          [&__pred,
-           &__table](_RandomAccessIterator __i, _RandomAccessIterator __j, _ReduceType __value) -> _ReduceType {
-            if (__value == __broken) {
-              return __broken;
-            }
-            _ReduceType __res = __not_init;
-            // if first element satisfy pred
-            if (__pred(*__i)) {
-              // find first element that don't satisfy pred
-              _RandomAccessIterator __x = __internal::__brick_find_if(__i + 1, __j, std::not_fn(__pred), _IsVector{});
-              if (__x != __j) {
-                // find first element after "x" that satisfy pred
-                _RandomAccessIterator __y = __internal::__brick_find_if(__x + 1, __j, __pred, _IsVector{});
-                // if it was found then range isn't partitioned by pred
-                if (__y != __j) {
-                  return __broken;
-                } else {
-                  __res = __true_false;
-                }
-              } else {
-                __res = __all_true;
-              }
-            } else { // if first element doesn't satisfy pred
-              // then we should find the first element that satisfy pred.
-              // If we found it then range isn't partitioned by pred
-              if (__internal::__brick_find_if(__i + 1, __j, __pred, _IsVector{}) != __j) {
-                return __broken;
-              } else {
-                __res = __all_false;
-              }
-            }
-            // if we have value from left range then we should calculate the result
-            return (__value == -1) ? __res : __table[__value * 4 + __res];
-          },
-
-          [&__table](_ReduceType __val1, _ReduceType __val2) -> _ReduceType {
-            if (__val1 == __broken || __val2 == __broken) {
-              return __broken;
-            }
-            // calculate the result for new big range
-            return __table[__val1 * 4 + __val2];
-          });
-      return __init != __broken;
-    });
-  }
-}
-
-//------------------------------------------------------------------------
-// partition
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _UnaryPredicate>
-_ForwardIterator __brick_partition(
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _UnaryPredicate __pred,
-    /*is_vector=*/std::false_type) noexcept {
-  return std::partition(__first, __last, __pred);
-}
-
-template <class _RandomAccessIterator, class _UnaryPredicate>
-_RandomAccessIterator __brick_partition(
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _UnaryPredicate __pred,
-    /*is_vector=*/std::true_type) noexcept {
-  // TODO: vectorize
-  return std::partition(__first, __last, __pred);
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate>
-_ForwardIterator __pattern_partition(
-    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _UnaryPredicate __pred) noexcept {
-  return __internal::__brick_partition(__first, __last, __pred, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _UnaryPredicate>
-_RandomAccessIterator __pattern_partition(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _UnaryPredicate __pred) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  // partitioned range: elements before pivot satisfy pred (true part),
-  //                    elements after pivot don't satisfy pred (false part)
-  struct _PartitionRange {
-    _RandomAccessIterator __begin;
-    _RandomAccessIterator __pivot;
-    _RandomAccessIterator __end;
-  };
-
-  return __internal::__except_handler([&]() {
-    _PartitionRange __init{__last, __last, __last};
-
-    // lambda for merging two partitioned ranges to one partitioned range
-    auto __reductor = [&__exec](_PartitionRange __val1, _PartitionRange __val2) -> _PartitionRange {
-      auto __size1     = __val1.__end - __val1.__pivot;
-      auto __size2     = __val2.__pivot - __val2.__begin;
-      auto __new_begin = __val2.__begin - (__val1.__end - __val1.__begin);
-
-      // if all elements in left range satisfy pred then we can move new pivot to pivot of right range
-      if (__val1.__end == __val1.__pivot) {
-        return {__new_begin, __val2.__pivot, __val2.__end};
-      }
-      // if true part of right range greater than false part of left range
-      // then we should swap the false part of left range and last part of true part of right range
-      else if (__size2 > __size1) {
-        __par_backend::__parallel_for(
-            __backend_tag{},
-            std::forward<_ExecutionPolicy>(__exec),
-            __val1.__pivot,
-            __val1.__pivot + __size1,
-            [__val1, __val2, __size1](_RandomAccessIterator __i, _RandomAccessIterator __j) {
-              __internal::__brick_swap_ranges(
-                  __i, __j, (__val2.__pivot - __size1) + (__i - __val1.__pivot), _IsVector{});
-            });
-        return {__new_begin, __val2.__pivot - __size1, __val2.__end};
-      }
-      // else we should swap the first part of false part of left range and true part of right range
-      else {
-        __par_backend::__parallel_for(
-            __backend_tag{},
-            std::forward<_ExecutionPolicy>(__exec),
-            __val1.__pivot,
-            __val1.__pivot + __size2,
-            [__val1, __val2](_RandomAccessIterator __i, _RandomAccessIterator __j) {
-              __internal::__brick_swap_ranges(__i, __j, __val2.__begin + (__i - __val1.__pivot), _IsVector{});
-            });
-        return {__new_begin, __val1.__pivot + __size2, __val2.__end};
-      }
-    };
-
-    _PartitionRange __result = __par_backend::__parallel_reduce(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first,
-        __last,
-        __init,
-        [__pred,
-         __reductor](_RandomAccessIterator __i, _RandomAccessIterator __j, _PartitionRange __value) -> _PartitionRange {
-          // 1. serial partition
-          _RandomAccessIterator __pivot = __internal::__brick_partition(__i, __j, __pred, _IsVector{});
-
-          // 2. merging of two ranges (left and right respectively)
-          return __reductor(__value, {__i, __pivot, __j});
-        },
-        __reductor);
-    return __result.__pivot;
-  });
-}
-
-//------------------------------------------------------------------------
-// stable_partition
-//------------------------------------------------------------------------
-
-template <class _BidirectionalIterator, class _UnaryPredicate>
-_BidirectionalIterator __brick_stable_partition(
-    _BidirectionalIterator __first,
-    _BidirectionalIterator __last,
-    _UnaryPredicate __pred,
-    /*__is_vector=*/std::false_type) noexcept {
-  return std::stable_partition(__first, __last, __pred);
-}
-
-template <class _RandomAccessIterator, class _UnaryPredicate>
-_RandomAccessIterator __brick_stable_partition(
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _UnaryPredicate __pred,
-    /*__is_vector=*/std::true_type) noexcept {
-  // TODO: vectorize
-  return std::stable_partition(__first, __last, __pred);
-}
-
-template <class _Tag, class _ExecutionPolicy, class _BidirectionalIterator, class _UnaryPredicate>
-_BidirectionalIterator __pattern_stable_partition(
-    _Tag,
-    _ExecutionPolicy&&,
-    _BidirectionalIterator __first,
-    _BidirectionalIterator __last,
-    _UnaryPredicate __pred) noexcept {
-  return __internal::__brick_stable_partition(__first, __last, __pred, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _UnaryPredicate>
-_RandomAccessIterator __pattern_stable_partition(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _UnaryPredicate __pred) noexcept {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  // partitioned range: elements before pivot satisfy pred (true part),
-  //                    elements after pivot don't satisfy pred (false part)
-  struct _PartitionRange {
-    _RandomAccessIterator __begin;
-    _RandomAccessIterator __pivot;
-    _RandomAccessIterator __end;
-  };
-
-  return __internal::__except_handler([&]() {
-    _PartitionRange __init{__last, __last, __last};
-
-    // lambda for merging two partitioned ranges to one partitioned range
-    auto __reductor = [](_PartitionRange __val1, _PartitionRange __val2) -> _PartitionRange {
-      auto __size1     = __val1.__end - __val1.__pivot;
-      auto __new_begin = __val2.__begin - (__val1.__end - __val1.__begin);
-
-      // if all elements in left range satisfy pred then we can move new pivot to pivot of right range
-      if (__val1.__end == __val1.__pivot) {
-        return {__new_begin, __val2.__pivot, __val2.__end};
-      }
-      // if true part of right range greater than false part of left range
-      // then we should swap the false part of left range and last part of true part of right range
-      else {
-        __internal::__brick_rotate(__val1.__pivot, __val2.__begin, __val2.__pivot, _IsVector{});
-        return {__new_begin, __val2.__pivot - __size1, __val2.__end};
-      }
-    };
-
-    _PartitionRange __result = __par_backend::__parallel_reduce(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first,
-        __last,
-        __init,
-        [&__pred,
-         __reductor](_RandomAccessIterator __i, _RandomAccessIterator __j, _PartitionRange __value) -> _PartitionRange {
-          // 1. serial stable_partition
-          _RandomAccessIterator __pivot = __internal::__brick_stable_partition(__i, __j, __pred, _IsVector{});
-
-          // 2. merging of two ranges (left and right respectively)
-          return __reductor(__value, {__i, __pivot, __j});
-        },
-        __reductor);
-    return __result.__pivot;
-  });
-}
-
-//------------------------------------------------------------------------
-// partition_copy
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _OutputIterator1, class _OutputIterator2, class _UnaryPredicate>
-std::pair<_OutputIterator1, _OutputIterator2> __brick_partition_copy(
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _OutputIterator1 __out_true,
-    _OutputIterator2 __out_false,
-    _UnaryPredicate __pred,
-    /*is_vector=*/std::false_type) noexcept {
-  return std::partition_copy(__first, __last, __out_true, __out_false, __pred);
-}
-
-template <class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _RandomAccessIterator3,
-          class _UnaryPredicate>
-std::pair<_RandomAccessIterator2, _RandomAccessIterator3> __brick_partition_copy(
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __out_true,
-    _RandomAccessIterator3 __out_false,
-    _UnaryPredicate __pred,
-    /*is_vector=*/std::true_type) noexcept {
-#if defined(_PSTL_MONOTONIC_PRESENT)
-  return __unseq_backend::__simd_partition_copy(__first, __last - __first, __out_true, __out_false, __pred);
-#else
-  return std::partition_copy(__first, __last, __out_true, __out_false, __pred);
-#endif
-}
-
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _ForwardIterator,
-          class _OutputIterator1,
-          class _OutputIterator2,
-          class _UnaryPredicate>
-std::pair<_OutputIterator1, _OutputIterator2> __pattern_partition_copy(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _OutputIterator1 __out_true,
-    _OutputIterator2 __out_false,
-    _UnaryPredicate __pred) noexcept {
-  return __internal::__brick_partition_copy(
-      __first, __last, __out_true, __out_false, __pred, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _RandomAccessIterator3,
-          class _UnaryPredicate>
-std::pair<_RandomAccessIterator2, _RandomAccessIterator3> __pattern_partition_copy(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __out_true,
-    _RandomAccessIterator3 __out_false,
-    _UnaryPredicate __pred) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  typedef typename std::iterator_traits<_RandomAccessIterator1>::
diff erence_type _DifferenceType;
-  typedef std::pair<_DifferenceType, _DifferenceType> _ReturnType;
-  const _DifferenceType __n = __last - __first;
-  if (_DifferenceType(1) < __n) {
-    __par_backend::__buffer<bool> __mask_buf(__n);
-    return __internal::__except_handler([&__exec, __n, __first, __out_true, __out_false, __pred, &__mask_buf]() {
-      bool* __mask = __mask_buf.get();
-      _ReturnType __m{};
-      __par_backend::__parallel_strict_scan(
-          __backend_tag{},
-          std::forward<_ExecutionPolicy>(__exec),
-          __n,
-          std::make_pair(_DifferenceType(0), _DifferenceType(0)),
-          [=](_DifferenceType __i, _DifferenceType __len) { // Reduce
-            return __internal::__brick_calc_mask_1<_DifferenceType>(
-                __first + __i, __first + (__i + __len), __mask + __i, __pred, _IsVector{});
-          },
-          [](const _ReturnType& __x, const _ReturnType& __y) -> _ReturnType {
-            return std::make_pair(__x.first + __y.first, __x.second + __y.second);
-          },                                                                       // Combine
-          [=](_DifferenceType __i, _DifferenceType __len, _ReturnType __initial) { // Scan
-            __internal::__brick_partition_by_mask(
-                __first + __i,
-                __first + (__i + __len),
-                __out_true + __initial.first,
-                __out_false + __initial.second,
-                __mask + __i,
-                _IsVector{});
-          },
-          [&__m](_ReturnType __total) { __m = __total; });
-      return std::make_pair(__out_true + __m.first, __out_false + __m.second);
-    });
-  }
-  // trivial sequence - use serial algorithm
-  return __internal::__brick_partition_copy(__first, __last, __out_true, __out_false, __pred, _IsVector{});
-}
-
-//------------------------------------------------------------------------
-// sort
-//------------------------------------------------------------------------
-
-template <class _Tag, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare, class _IsMoveConstructible>
-void __pattern_sort(_Tag,
-                    _ExecutionPolicy&&,
-                    _RandomAccessIterator __first,
-                    _RandomAccessIterator __last,
-                    _Compare __comp,
-                    _IsMoveConstructible) noexcept {
-  std::sort(__first, __last, __comp);
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-void __pattern_sort(__parallel_tag<_IsVector> __tag,
-                    _ExecutionPolicy&& __exec,
-                    _RandomAccessIterator __first,
-                    _RandomAccessIterator __last,
-                    _Compare __comp,
-                    /*is_move_constructible=*/std::true_type) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  __internal::__except_handler([&]() {
-    __par_backend::__parallel_stable_sort(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first,
-        __last,
-        __comp,
-        [](_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) {
-          std::sort(__first, __last, __comp);
-        });
-  });
-}
-
-//------------------------------------------------------------------------
-// stable_sort
-//------------------------------------------------------------------------
-
-template <class _Tag, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-void __pattern_stable_sort(
-    _Tag, _ExecutionPolicy&&, _RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) noexcept {
-  std::stable_sort(__first, __last, __comp);
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-void __pattern_stable_sort(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _Compare __comp) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  __internal::__except_handler([&]() {
-    __par_backend::__parallel_stable_sort(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first,
-        __last,
-        __comp,
-        [](_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) {
-          std::stable_sort(__first, __last, __comp);
-        });
-  });
-}
-
-//------------------------------------------------------------------------
-// partial_sort
-//------------------------------------------------------------------------
-
-template <class _Tag, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-void __pattern_partial_sort(
-    _Tag,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __middle,
-    _RandomAccessIterator __last,
-    _Compare __comp) noexcept {
-  std::partial_sort(__first, __middle, __last, __comp);
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-void __pattern_partial_sort(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __middle,
-    _RandomAccessIterator __last,
-    _Compare __comp) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  const auto __n = __middle - __first;
-  if (__n == 0)
-    return;
-
-  __internal::__except_handler([&]() {
-    __par_backend::__parallel_stable_sort(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first,
-        __last,
-        __comp,
-        [__n](_RandomAccessIterator __begin, _RandomAccessIterator __end, _Compare __comp) {
-          if (__n < __end - __begin)
-            std::partial_sort(__begin, __begin + __n, __end, __comp);
-          else
-            std::sort(__begin, __end, __comp);
-        },
-        __n);
-  });
-}
-
-//------------------------------------------------------------------------
-// partial_sort_copy
-//------------------------------------------------------------------------
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _RandomAccessIterator, class _Compare>
-_RandomAccessIterator __pattern_partial_sort_copy(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _RandomAccessIterator __d_first,
-    _RandomAccessIterator __d_last,
-    _Compare __comp) noexcept {
-  return std::partial_sort_copy(__first, __last, __d_first, __d_last, __comp);
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _Compare>
-_RandomAccessIterator2 __pattern_partial_sort_copy(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __d_first,
-    _RandomAccessIterator2 __d_last,
-    _Compare __comp) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  if (__last == __first || __d_last == __d_first) {
-    return __d_first;
-  }
-  auto __n1 = __last - __first;
-  auto __n2 = __d_last - __d_first;
-  return __internal::__except_handler([&]() {
-    if (__n2 >= __n1) {
-      __par_backend::__parallel_stable_sort(
-          __backend_tag{},
-          std::forward<_ExecutionPolicy>(__exec),
-          __d_first,
-          __d_first + __n1,
-          __comp,
-          [__first, __d_first](_RandomAccessIterator2 __i, _RandomAccessIterator2 __j, _Compare __comp) {
-            _RandomAccessIterator1 __i1 = __first + (__i - __d_first);
-            _RandomAccessIterator1 __j1 = __first + (__j - __d_first);
-
-        // 1. Copy elements from input to output
-#if !defined(_PSTL_ICC_18_OMP_SIMD_BROKEN)
-            __internal::__brick_copy(__i1, __j1, __i, _IsVector{});
-#else
-            std::copy(__i1, __j1, __i);
-#endif
-            // 2. Sort elements in output sequence
-            std::sort(__i, __j, __comp);
-          },
-          __n1);
-      return __d_first + __n1;
-    } else {
-      typedef typename std::iterator_traits<_RandomAccessIterator1>::value_type _T1;
-      typedef typename std::iterator_traits<_RandomAccessIterator2>::value_type _T2;
-      __par_backend::__buffer<_T1> __buf(__n1);
-      _T1* __r = __buf.get();
-
-      __par_backend::__parallel_stable_sort(
-          __backend_tag{},
-          std::forward<_ExecutionPolicy>(__exec),
-          __r,
-          __r + __n1,
-          __comp,
-          [__n2, __first, __r](_T1* __i, _T1* __j, _Compare __comp) {
-            _RandomAccessIterator1 __it = __first + (__i - __r);
-
-            // 1. Copy elements from input to raw memory
-            for (_T1* __k = __i; __k != __j; ++__k, ++__it) {
-              ::new (__k) _T2(*__it);
-            }
-
-            // 2. Sort elements in temporary __buffer
-            if (__n2 < __j - __i)
-              std::partial_sort(__i, __i + __n2, __j, __comp);
-            else
-              std::sort(__i, __j, __comp);
-          },
-          __n2);
-
-      // 3. Move elements from temporary __buffer to output
-      __par_backend::__parallel_for(
-          __backend_tag{},
-          std::forward<_ExecutionPolicy>(__exec),
-          __r,
-          __r + __n2,
-          [__r, __d_first](_T1* __i, _T1* __j) {
-            __brick_move_destroy()(__i, __j, __d_first + (__i - __r), _IsVector{});
-          });
-      __par_backend::__parallel_for(
-          __backend_tag{}, std::forward<_ExecutionPolicy>(__exec), __r + __n2, __r + __n1, [](_T1* __i, _T1* __j) {
-            __brick_destroy(__i, __j, _IsVector{});
-          });
-
-      return __d_first + __n2;
-    }
-  });
-}
-
-//------------------------------------------------------------------------
-// adjacent_find
-//------------------------------------------------------------------------
-template <class _RandomAccessIterator, class _BinaryPredicate>
-_RandomAccessIterator __brick_adjacent_find(
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _BinaryPredicate __pred,
-    /* IsVector = */ std::true_type,
-    bool __or_semantic) noexcept {
-  return __unseq_backend::__simd_adjacent_find(__first, __last, __pred, __or_semantic);
-}
-
-template <class _ForwardIterator, class _BinaryPredicate>
-_ForwardIterator __brick_adjacent_find(
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _BinaryPredicate __pred,
-    /* IsVector = */ std::false_type,
-    bool) noexcept {
-  return std::adjacent_find(__first, __last, __pred);
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _BinaryPredicate>
-_ForwardIterator __pattern_adjacent_find(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _BinaryPredicate __pred,
-    bool __or_semantic) noexcept {
-  return __internal::__brick_adjacent_find(__first, __last, __pred, typename _Tag::__is_vector{}, __or_semantic);
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _BinaryPredicate>
-_RandomAccessIterator __pattern_adjacent_find(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _BinaryPredicate __pred,
-    bool __or_semantic) {
-  if (__last - __first < 2)
-    return __last;
-
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  return __internal::__except_handler([&]() {
-    return __par_backend::__parallel_reduce(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first,
-        __last,
-        __last,
-        [__last, __pred, __or_semantic](
-            _RandomAccessIterator __begin, _RandomAccessIterator __end, _RandomAccessIterator __value)
-            -> _RandomAccessIterator {
-          // TODO: investigate performance benefits from the use of shared variable for the result,
-          // checking (compare_and_swap idiom) its __value at __first.
-          if (__or_semantic && __value < __last) { // found
-            __par_backend::__cancel_execution();
-            return __value;
-          }
-
-          if (__value > __begin) {
-            // modify __end to check the predicate on the boundary __values;
-            // TODO: to use a custom range with boundaries overlapping
-            // TODO: investigate what if we remove "if" below and run algorithm on range [__first, __last-1)
-            // then check the pair [__last-1, __last)
-            if (__end != __last)
-              ++__end;
-
-            // correct the global result iterator if the "brick" returns a local "__last"
-            const _RandomAccessIterator __res =
-                __internal::__brick_adjacent_find(__begin, __end, __pred, _IsVector{}, __or_semantic);
-            if (__res < __end)
-              __value = __res;
-          }
-          return __value;
-        },
-        [](_RandomAccessIterator __x, _RandomAccessIterator __y) -> _RandomAccessIterator {
-          return __x < __y ? __x : __y;
-        } // reduce a __value
-    );
-  });
-}
-
-//------------------------------------------------------------------------
-// nth_element
-//------------------------------------------------------------------------
-
-template <class _Tag, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-void __pattern_nth_element(
-    _Tag,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __nth,
-    _RandomAccessIterator __last,
-    _Compare __comp) noexcept {
-  std::nth_element(__first, __nth, __last, __comp);
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-void __pattern_nth_element(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __nth,
-    _RandomAccessIterator __last,
-    _Compare __comp) noexcept {
-  if (__first == __last || __nth == __last) {
-    return;
-  }
-
-  using std::iter_swap;
-  typedef typename std::iterator_traits<_RandomAccessIterator>::value_type _Tp;
-  _RandomAccessIterator __x;
-  do {
-    __x = __internal::__pattern_partition(
-        __tag, std::forward<_ExecutionPolicy>(__exec), __first + 1, __last, [&__comp, __first](const _Tp& __x) {
-          return __comp(__x, *__first);
-        });
-    --__x;
-    if (__x != __first) {
-      iter_swap(__first, __x);
-    }
-    // if x > nth then our new range for partition is [first, x)
-    if (__x - __nth > 0) {
-      __last = __x;
-    }
-    // if x < nth then our new range for partition is [x, last)
-    else if (__x - __nth < 0) {
-      // if *x == *nth then we can start new partition with x+1
-      if (!__comp(*__nth, *__x) && !__comp(*__x, *__nth)) {
-        ++__x;
-      } else {
-        iter_swap(__nth, __x);
-      }
-      __first = __x;
-    }
-  } while (__x != __nth);
-}
-
-//------------------------------------------------------------------------
-// generate, generate_n
-//------------------------------------------------------------------------
-template <class _RandomAccessIterator, class _Generator>
-void __brick_generate(_RandomAccessIterator __first,
-                      _RandomAccessIterator __last,
-                      _Generator __g,
-                      /* is_vector = */ std::true_type) noexcept {
-  __unseq_backend::__simd_generate_n(__first, __last - __first, __g);
-}
-
-template <class _ForwardIterator, class _Generator>
-void __brick_generate(_ForwardIterator __first,
-                      _ForwardIterator __last,
-                      _Generator __g,
-                      /* is_vector = */ std::false_type) noexcept {
-  std::generate(__first, __last, __g);
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Generator>
-void __pattern_generate(
-    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Generator __g) noexcept {
-  __internal::__brick_generate(__first, __last, __g, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Generator>
-_RandomAccessIterator __pattern_generate(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _Generator __g) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  return __internal::__except_handler([&]() {
-    __par_backend::__parallel_for(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first,
-        __last,
-        [__g](_RandomAccessIterator __begin, _RandomAccessIterator __end) {
-          __internal::__brick_generate(__begin, __end, __g, _IsVector{});
-        });
-    return __last;
-  });
-}
-
-template <class _RandomAccessIterator, class Size, class _Generator>
-_RandomAccessIterator __brick_generate_n(
-    _RandomAccessIterator __first,
-    Size __count,
-    _Generator __g,
-    /* is_vector = */ std::true_type) noexcept {
-  return __unseq_backend::__simd_generate_n(__first, __count, __g);
-}
-
-template <class OutputIterator, class Size, class _Generator>
-OutputIterator
-__brick_generate_n(OutputIterator __first, Size __count, _Generator __g, /* is_vector = */ std::false_type) noexcept {
-  return std::generate_n(__first, __count, __g);
-}
-
-template <class _Tag, class _ExecutionPolicy, class _OutputIterator, class _Size, class _Generator>
-_OutputIterator
-__pattern_generate_n(_Tag, _ExecutionPolicy&&, _OutputIterator __first, _Size __count, _Generator __g) noexcept {
-  return __internal::__brick_generate_n(__first, __count, __g, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Size, class _Generator>
-_RandomAccessIterator __pattern_generate_n(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _Size __count,
-    _Generator __g) {
-  static_assert(__are_random_access_iterators<_RandomAccessIterator>::value,
-                "Pattern-brick error. Should be a random access iterator.");
-  return __internal::__pattern_generate(__tag, std::forward<_ExecutionPolicy>(__exec), __first, __first + __count, __g);
-}
-
-//------------------------------------------------------------------------
-// remove
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _UnaryPredicate>
-_ForwardIterator __brick_remove_if(
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _UnaryPredicate __pred,
-    /* __is_vector = */ std::false_type) noexcept {
-  return std::remove_if(__first, __last, __pred);
-}
-
-template <class _RandomAccessIterator, class _UnaryPredicate>
-_RandomAccessIterator __brick_remove_if(
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _UnaryPredicate __pred,
-    /* __is_vector = */ std::true_type) noexcept {
-#if defined(_PSTL_MONOTONIC_PRESENT)
-  return __unseq_backend::__simd_remove_if(__first, __last - __first, __pred);
-#else
-  return std::remove_if(__first, __last, __pred);
-#endif
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate>
-_ForwardIterator __pattern_remove_if(
-    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _UnaryPredicate __pred) noexcept {
-  return __internal::__brick_remove_if(__first, __last, __pred, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _UnaryPredicate>
-_RandomAccessIterator __pattern_remove_if(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _UnaryPredicate __pred) noexcept {
-  typedef typename std::iterator_traits<_RandomAccessIterator>::reference _ReferenceType;
-
-  if (__first == __last || __first + 1 == __last) {
-    // Trivial sequence - use serial algorithm
-    return __internal::__brick_remove_if(__first, __last, __pred, _IsVector{});
-  }
-
-  return __internal::__remove_elements(
-      __tag,
-      std::forward<_ExecutionPolicy>(__exec),
-      __first,
-      __last,
-      [&__pred](bool* __b, bool* __e, _RandomAccessIterator __it) {
-        __internal::__brick_walk2(
-            __b, __e, __it, [&__pred](bool& __x, _ReferenceType __y) { __x = !__pred(__y); }, _IsVector{});
-      });
-}
-
-//------------------------------------------------------------------------
-// inplace_merge
-//------------------------------------------------------------------------
-template <class _BidirectionalIterator, class _Compare>
-void __brick_inplace_merge(
-    _BidirectionalIterator __first,
-    _BidirectionalIterator __middle,
-    _BidirectionalIterator __last,
-    _Compare __comp,
-    /* __is_vector = */ std::false_type) noexcept {
-  std::inplace_merge(__first, __middle, __last, __comp);
-}
-
-template <class _RandomAccessIterator, class _Compare>
-void __brick_inplace_merge(
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __middle,
-    _RandomAccessIterator __last,
-    _Compare __comp,
-    /* __is_vector = */ std::true_type) noexcept {
-  // TODO: vectorize
-  std::inplace_merge(__first, __middle, __last, __comp);
-}
-
-template <class _Tag, class _ExecutionPolicy, class _BidirectionalIterator, class _Compare>
-void __pattern_inplace_merge(
-    _Tag,
-    _ExecutionPolicy&&,
-    _BidirectionalIterator __first,
-    _BidirectionalIterator __middle,
-    _BidirectionalIterator __last,
-    _Compare __comp) noexcept {
-  __internal::__brick_inplace_merge(__first, __middle, __last, __comp, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-void __pattern_inplace_merge(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __middle,
-    _RandomAccessIterator __last,
-    _Compare __comp) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  if (__first == __last || __first == __middle || __middle == __last) {
-    return;
-  }
-  typedef typename std::iterator_traits<_RandomAccessIterator>::value_type _Tp;
-  auto __n = __last - __first;
-  __par_backend::__buffer<_Tp> __buf(__n);
-  _Tp* __r = __buf.get();
-  __internal::__except_handler([&]() {
-    auto __move_values = [](_RandomAccessIterator __x, _Tp* __z) {
-      __internal::__invoke_if_else(
-          std::is_trivial<_Tp>(),
-          [&]() { *__z = std::move(*__x); },
-          [&]() { ::new (std::addressof(*__z)) _Tp(std::move(*__x)); });
-    };
-
-    auto __move_sequences = [](_RandomAccessIterator __first1, _RandomAccessIterator __last1, _Tp* __first2) {
-      return __internal::__brick_uninitialized_move(__first1, __last1, __first2, _IsVector());
-    };
-
-    __par_backend::__parallel_merge(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first,
-        __middle,
-        __middle,
-        __last,
-        __r,
-        __comp,
-        [__n, __move_values, __move_sequences](
-            _RandomAccessIterator __f1,
-            _RandomAccessIterator __l1,
-            _RandomAccessIterator __f2,
-            _RandomAccessIterator __l2,
-            _Tp* __f3,
-            _Compare __comp) {
-          (__utils::__serial_move_merge(__n))(
-              __f1, __l1, __f2, __l2, __f3, __comp, __move_values, __move_values, __move_sequences, __move_sequences);
-          return __f3 + (__l1 - __f1) + (__l2 - __f2);
-        });
-    __par_backend::__parallel_for(
-        __backend_tag{}, std::forward<_ExecutionPolicy>(__exec), __r, __r + __n, [__r, __first](_Tp* __i, _Tp* __j) {
-          __brick_move_destroy()(__i, __j, __first + (__i - __r), _IsVector{});
-        });
-  });
-}
-
-//------------------------------------------------------------------------
-// includes
-//------------------------------------------------------------------------
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Compare>
-bool __pattern_includes(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _Compare __comp) noexcept {
-  return std::includes(__first1, __last1, __first2, __last2, __comp);
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _Compare>
-bool __pattern_includes(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first1,
-    _RandomAccessIterator1 __last1,
-    _RandomAccessIterator2 __first2,
-    _RandomAccessIterator2 __last2,
-    _Compare __comp) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  if (__first2 >= __last2)
-    return true;
-
-  if (__first1 >= __last1 || __comp(*__first2, *__first1) || __comp(*(__last1 - 1), *(__last2 - 1)))
-    return false;
-
-  __first1 = std::lower_bound(__first1, __last1, *__first2, __comp);
-  if (__first1 == __last1)
-    return false;
-
-  if (__last2 - __first2 == 1)
-    return !__comp(*__first1, *__first2) && !__comp(*__first2, *__first1);
-
-  return __internal::__except_handler([&]() {
-    return !__internal::__parallel_or(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first2,
-        __last2,
-        [__first1, __last1, __first2, __last2, &__comp](_RandomAccessIterator2 __i, _RandomAccessIterator2 __j) {
-          _LIBCPP_ASSERT_UNCATEGORIZED(__j > __i, "");
-          //_LIBCPP_ASSERT_UNCATEGORIZED(__j - __i > 1, "");
-
-          // 1. moving boundaries to "consume" subsequence of equal elements
-          auto __is_equal = [&__comp](_RandomAccessIterator2 __a, _RandomAccessIterator2 __b) -> bool {
-            return !__comp(*__a, *__b) && !__comp(*__b, *__a);
-          };
-
-          // 1.1 left bound, case "aaa[aaaxyz...]" - searching "x"
-          if (__i > __first2 && __is_equal(__i, __i - 1)) {
-            // whole subrange continues to content equal elements - return "no op"
-            if (__is_equal(__i, __j - 1))
-              return false;
-
-            __i = std::upper_bound(__i, __last2, *__i, __comp);
-          }
-
-          // 1.2 right bound, case "[...aaa]aaaxyz" - searching "x"
-          if (__j < __last2 && __is_equal(__j - 1, __j))
-            __j = std::upper_bound(__j, __last2, *__j, __comp);
-
-          // 2. testing is __a subsequence of the second range included into the first range
-          auto __b = std::lower_bound(__first1, __last1, *__i, __comp);
-
-          _LIBCPP_ASSERT_UNCATEGORIZED(!__comp(*(__last1 - 1), *__b), "");
-          _LIBCPP_ASSERT_UNCATEGORIZED(!__comp(*(__j - 1), *__i), "");
-          return !std::includes(__b, __last1, __i, __j, __comp);
-        });
-  });
-}
-
-constexpr auto __set_algo_cut_off = 1000;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _OutputIterator,
-          class _Compare,
-          class _SizeFunction,
-          class _SetOP>
-_OutputIterator __parallel_set_op(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _OutputIterator __result,
-    _Compare __comp,
-    _SizeFunction __size_func,
-    _SetOP __set_op) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  typedef typename std::iterator_traits<_ForwardIterator1>::
diff erence_type _DifferenceType;
-  typedef typename std::iterator_traits<_OutputIterator>::value_type _Tp;
-
-  struct _SetRange {
-    _DifferenceType __pos, __len, __buf_pos;
-    bool empty() const { return __len == 0; }
-  };
-
-  const _DifferenceType __n1 = __last1 - __first1;
-  const _DifferenceType __n2 = __last2 - __first2;
-
-  __par_backend::__buffer<_Tp> __buf(__size_func(__n1, __n2));
-
-  return __internal::__except_handler(
-      [&__exec, __n1, __first1, __last1, __first2, __last2, __result, __comp, __size_func, __set_op, &__buf]() {
-        auto __buffer = __buf.get();
-        _DifferenceType __m{};
-        auto __scan = [=](_DifferenceType, _DifferenceType, const _SetRange& __s) { // Scan
-          if (!__s.empty())
-            __brick_move_destroy()(
-                __buffer + __s.__buf_pos, __buffer + (__s.__buf_pos + __s.__len), __result + __s.__pos, _IsVector{});
-        };
-        __par_backend::__parallel_strict_scan(
-            __backend_tag{},
-            std::forward<_ExecutionPolicy>(__exec),
-            __n1,
-            _SetRange{0, 0, 0},                               //-1, 0},
-            [=](_DifferenceType __i, _DifferenceType __len) { // Reduce
-              //[__b; __e) - a subrange of the first sequence, to reduce
-              _ForwardIterator1 __b = __first1 + __i, __e = __first1 + (__i + __len);
-
-              // try searching for the first element which not equal to *__b
-              if (__b != __first1)
-                __b = std::upper_bound(__b, __last1, *__b, __comp);
-
-              // try searching for the first element which not equal to *__e
-              if (__e != __last1)
-                __e = std::upper_bound(__e, __last1, *__e, __comp);
-
-              // check is [__b; __e) empty
-              if (__e - __b < 1) {
-                _ForwardIterator2 __bb = __last2;
-                if (__b != __last1)
-                  __bb = std::lower_bound(__first2, __last2, *__b, __comp);
-
-                const _DifferenceType __buf_pos = __size_func((__b - __first1), (__bb - __first2));
-                return _SetRange{0, 0, __buf_pos};
-              }
-
-              // try searching for "corresponding" subrange [__bb; __ee) in the second sequence
-              _ForwardIterator2 __bb = __first2;
-              if (__b != __first1)
-                __bb = std::lower_bound(__first2, __last2, *__b, __comp);
-
-              _ForwardIterator2 __ee = __last2;
-              if (__e != __last1)
-                __ee = std::lower_bound(__bb, __last2, *__e, __comp);
-
-              const _DifferenceType __buf_pos = __size_func((__b - __first1), (__bb - __first2));
-              auto __buffer_b                 = __buffer + __buf_pos;
-              auto __res                      = __set_op(__b, __e, __bb, __ee, __buffer_b, __comp);
-
-              return _SetRange{0, __res - __buffer_b, __buf_pos};
-            },
-            [](const _SetRange& __a, const _SetRange& __b) { // Combine
-              if (__b.__buf_pos > __a.__buf_pos || ((__b.__buf_pos == __a.__buf_pos) && !__b.empty()))
-                return _SetRange{__a.__pos + __a.__len + __b.__pos, __b.__len, __b.__buf_pos};
-              return _SetRange{__b.__pos + __b.__len + __a.__pos, __a.__len, __a.__buf_pos};
-            },
-            __scan,                                     // Scan
-            [&__m, &__scan](const _SetRange& __total) { // Apex
-              // final scan
-              __scan(0, 0, __total);
-              __m = __total.__pos + __total.__len;
-            });
-        return __result + __m;
-      });
-}
-
-// a shared parallel pattern for '__pattern_set_union' and '__pattern_set_symmetric_
diff erence'
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _OutputIterator,
-          class _Compare,
-          class _SetUnionOp>
-_OutputIterator __parallel_set_union_op(
-    _Tag __tag,
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _OutputIterator __result,
-    _Compare __comp,
-    _SetUnionOp __set_union_op) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  typedef typename std::iterator_traits<_ForwardIterator1>::
diff erence_type _DifferenceType;
-
-  const auto __n1 = __last1 - __first1;
-  const auto __n2 = __last2 - __first2;
-
-  auto copy_range1 = [](_ForwardIterator1 __begin, _ForwardIterator1 __end, _OutputIterator __res) {
-    return __internal::__brick_copy(__begin, __end, __res, typename _Tag::__is_vector{});
-  };
-  auto copy_range2 = [](_ForwardIterator2 __begin, _ForwardIterator2 __end, _OutputIterator __res) {
-    return __internal::__brick_copy(__begin, __end, __res, typename _Tag::__is_vector{});
-  };
-
-  // {1} {}: parallel copying just first sequence
-  if (__n2 == 0)
-    return __internal::__pattern_walk2_brick(
-        __tag, std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __result, copy_range1);
-
-  // {} {2}: parallel copying justmake  second sequence
-  if (__n1 == 0)
-    return __internal::__pattern_walk2_brick(
-        __tag, std::forward<_ExecutionPolicy>(__exec), __first2, __last2, __result, copy_range2);
-
-  // testing  whether the sequences are intersected
-  _ForwardIterator1 __left_bound_seq_1 = std::lower_bound(__first1, __last1, *__first2, __comp);
-
-  if (__left_bound_seq_1 == __last1) {
-    //{1} < {2}: seq2 is wholly greater than seq1, so, do parallel copying seq1 and seq2
-    __par_backend::__parallel_invoke(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        [=] {
-          __internal::__pattern_walk2_brick(
-              __tag, std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __result, copy_range1);
-        },
-        [=] {
-          __internal::__pattern_walk2_brick(
-              __tag, std::forward<_ExecutionPolicy>(__exec), __first2, __last2, __result + __n1, copy_range2);
-        });
-    return __result + __n1 + __n2;
-  }
-
-  // testing  whether the sequences are intersected
-  _ForwardIterator2 __left_bound_seq_2 = std::lower_bound(__first2, __last2, *__first1, __comp);
-
-  if (__left_bound_seq_2 == __last2) {
-    //{2} < {1}: seq2 is wholly greater than seq1, so, do parallel copying seq1 and seq2
-    __par_backend::__parallel_invoke(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        [=] {
-          __internal::__pattern_walk2_brick(
-              __tag, std::forward<_ExecutionPolicy>(__exec), __first2, __last2, __result, copy_range2);
-        },
-        [=] {
-          __internal::__pattern_walk2_brick(
-              __tag, std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __result + __n2, copy_range1);
-        });
-    return __result + __n1 + __n2;
-  }
-
-  const auto __m1 = __left_bound_seq_1 - __first1;
-  if (__m1 > __set_algo_cut_off) {
-    auto __res_or = __result;
-    __result += __m1; // we know proper offset due to [first1; left_bound_seq_1) < [first2; last2)
-    __par_backend::__parallel_invoke(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        // do parallel copying of [first1; left_bound_seq_1)
-        [=] {
-          __internal::__pattern_walk2_brick(
-              __tag, std::forward<_ExecutionPolicy>(__exec), __first1, __left_bound_seq_1, __res_or, copy_range1);
-        },
-        [=, &__result] {
-          __result = __internal::__parallel_set_op(
-              __tag,
-              std::forward<_ExecutionPolicy>(__exec),
-              __left_bound_seq_1,
-              __last1,
-              __first2,
-              __last2,
-              __result,
-              __comp,
-              [](_DifferenceType __n, _DifferenceType __m) { return __n + __m; },
-              __set_union_op);
-        });
-    return __result;
-  }
-
-  const auto __m2 = __left_bound_seq_2 - __first2;
-  _LIBCPP_ASSERT_UNCATEGORIZED(__m1 == 0 || __m2 == 0, "");
-  if (__m2 > __set_algo_cut_off) {
-    auto __res_or = __result;
-    __result += __m2; // we know proper offset due to [first2; left_bound_seq_2) < [first1; last1)
-    __par_backend::__parallel_invoke(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        // do parallel copying of [first2; left_bound_seq_2)
-        [=] {
-          __internal::__pattern_walk2_brick(
-              __tag, std::forward<_ExecutionPolicy>(__exec), __first2, __left_bound_seq_2, __res_or, copy_range2);
-        },
-        [=, &__result] {
-          __result = __internal::__parallel_set_op(
-              __tag,
-              std::forward<_ExecutionPolicy>(__exec),
-              __first1,
-              __last1,
-              __left_bound_seq_2,
-              __last2,
-              __result,
-              __comp,
-              [](_DifferenceType __n, _DifferenceType __m) { return __n + __m; },
-              __set_union_op);
-        });
-    return __result;
-  }
-
-  return __internal::__parallel_set_op(
-      __tag,
-      std::forward<_ExecutionPolicy>(__exec),
-      __first1,
-      __last1,
-      __first2,
-      __last2,
-      __result,
-      __comp,
-      [](_DifferenceType __n, _DifferenceType __m) { return __n + __m; },
-      __set_union_op);
-}
-
-//------------------------------------------------------------------------
-// set_union
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
-_OutputIterator __brick_set_union(
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _OutputIterator __result,
-    _Compare __comp,
-    /*__is_vector=*/std::false_type) noexcept {
-  return std::set_union(__first1, __last1, __first2, __last2, __result, __comp);
-}
-
-template <typename _IsVector>
-struct __BrickCopyConstruct {
-  template <typename _ForwardIterator, typename _OutputIterator>
-  _OutputIterator operator()(_ForwardIterator __first, _ForwardIterator __last, _OutputIterator __result) {
-    return __brick_uninitialized_copy(__first, __last, __result, _IsVector());
-  }
-};
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _OutputIterator, class _Compare>
-_OutputIterator __brick_set_union(
-    _RandomAccessIterator1 __first1,
-    _RandomAccessIterator1 __last1,
-    _RandomAccessIterator2 __first2,
-    _RandomAccessIterator2 __last2,
-    _OutputIterator __result,
-    _Compare __comp,
-    /*__is_vector=*/std::true_type) noexcept {
-  // TODO: vectorize
-  return std::set_union(__first1, __last1, __first2, __last2, __result, __comp);
-}
-
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _OutputIterator,
-          class _Compare>
-_OutputIterator __pattern_set_union(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _OutputIterator __result,
-    _Compare __comp) noexcept {
-  return __internal::__brick_set_union(
-      __first1, __last1, __first2, __last2, __result, __comp, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _OutputIterator,
-          class _Compare>
-_OutputIterator __pattern_set_union(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first1,
-    _RandomAccessIterator1 __last1,
-    _RandomAccessIterator2 __first2,
-    _RandomAccessIterator2 __last2,
-    _OutputIterator __result,
-    _Compare __comp) {
-  const auto __n1 = __last1 - __first1;
-  const auto __n2 = __last2 - __first2;
-
-  // use serial algorithm
-  if (__n1 + __n2 <= __set_algo_cut_off)
-    return std::set_union(__first1, __last1, __first2, __last2, __result, __comp);
-
-  typedef typename std::iterator_traits<_OutputIterator>::value_type _Tp;
-  return __parallel_set_union_op(
-      __tag,
-      std::forward<_ExecutionPolicy>(__exec),
-      __first1,
-      __last1,
-      __first2,
-      __last2,
-      __result,
-      __comp,
-      [](_RandomAccessIterator1 __first1,
-         _RandomAccessIterator1 __last1,
-         _RandomAccessIterator2 __first2,
-         _RandomAccessIterator2 __last2,
-         _Tp* __result,
-         _Compare __comp) {
-        return __pstl::__utils::__set_union_construct(
-            __first1, __last1, __first2, __last2, __result, __comp, __BrickCopyConstruct<_IsVector>());
-      });
-}
-
-//------------------------------------------------------------------------
-// set_intersection
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
-_OutputIterator __brick_set_intersection(
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _OutputIterator __result,
-    _Compare __comp,
-    /*__is_vector=*/std::false_type) noexcept {
-  return std::set_intersection(__first1, __last1, __first2, __last2, __result, __comp);
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _RandomAccessIterator3, class _Compare>
-_RandomAccessIterator3 __brick_set_intersection(
-    _RandomAccessIterator1 __first1,
-    _RandomAccessIterator1 __last1,
-    _RandomAccessIterator2 __first2,
-    _RandomAccessIterator2 __last2,
-    _RandomAccessIterator3 __result,
-    _Compare __comp,
-    /*__is_vector=*/std::true_type) noexcept {
-  // TODO: vectorize
-  return std::set_intersection(__first1, __last1, __first2, __last2, __result, __comp);
-}
-
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _OutputIterator,
-          class _Compare>
-_OutputIterator __pattern_set_intersection(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _OutputIterator __result,
-    _Compare __comp) noexcept {
-  return __internal::__brick_set_intersection(
-      __first1, __last1, __first2, __last2, __result, __comp, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _RandomAccessIterator3,
-          class _Compare>
-_RandomAccessIterator3 __pattern_set_intersection(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first1,
-    _RandomAccessIterator1 __last1,
-    _RandomAccessIterator2 __first2,
-    _RandomAccessIterator2 __last2,
-    _RandomAccessIterator3 __result,
-    _Compare __comp) {
-  typedef typename std::iterator_traits<_RandomAccessIterator3>::value_type _Tp;
-  typedef typename std::iterator_traits<_RandomAccessIterator1>::
diff erence_type _DifferenceType;
-
-  const auto __n1 = __last1 - __first1;
-  const auto __n2 = __last2 - __first2;
-
-  // intersection is empty
-  if (__n1 == 0 || __n2 == 0)
-    return __result;
-
-  // testing  whether the sequences are intersected
-  _RandomAccessIterator1 __left_bound_seq_1 = std::lower_bound(__first1, __last1, *__first2, __comp);
-  //{1} < {2}: seq 2 is wholly greater than seq 1, so, the intersection is empty
-  if (__left_bound_seq_1 == __last1)
-    return __result;
-
-  // testing  whether the sequences are intersected
-  _RandomAccessIterator2 __left_bound_seq_2 = std::lower_bound(__first2, __last2, *__first1, __comp);
-  //{2} < {1}: seq 1 is wholly greater than seq 2, so, the intersection is empty
-  if (__left_bound_seq_2 == __last2)
-    return __result;
-
-  const auto __m1 = __last1 - __left_bound_seq_1 + __n2;
-  if (__m1 > __set_algo_cut_off) {
-    // we know proper offset due to [first1; left_bound_seq_1) < [first2; last2)
-    return __internal::__parallel_set_op(
-        __tag,
-        std::forward<_ExecutionPolicy>(__exec),
-        __left_bound_seq_1,
-        __last1,
-        __first2,
-        __last2,
-        __result,
-        __comp,
-        [](_DifferenceType __n, _DifferenceType __m) { return std::min(__n, __m); },
-        [](_RandomAccessIterator1 __first1,
-           _RandomAccessIterator1 __last1,
-           _RandomAccessIterator2 __first2,
-           _RandomAccessIterator2 __last2,
-           _Tp* __result,
-           _Compare __comp) {
-          return __pstl::__utils::__set_intersection_construct(__first1, __last1, __first2, __last2, __result, __comp);
-        });
-  }
-
-  const auto __m2 = __last2 - __left_bound_seq_2 + __n1;
-  if (__m2 > __set_algo_cut_off) {
-    // we know proper offset due to [first2; left_bound_seq_2) < [first1; last1)
-    __result = __internal::__parallel_set_op(
-        __tag,
-        std::forward<_ExecutionPolicy>(__exec),
-        __first1,
-        __last1,
-        __left_bound_seq_2,
-        __last2,
-        __result,
-        __comp,
-        [](_DifferenceType __n, _DifferenceType __m) { return std::min(__n, __m); },
-        [](_RandomAccessIterator1 __first1,
-           _RandomAccessIterator1 __last1,
-           _RandomAccessIterator2 __first2,
-           _RandomAccessIterator2 __last2,
-           _Tp* __result,
-           _Compare __comp) {
-          return __pstl::__utils::__set_intersection_construct(__first2, __last2, __first1, __last1, __result, __comp);
-        });
-    return __result;
-  }
-
-  // [left_bound_seq_1; last1) and [left_bound_seq_2; last2) - use serial algorithm
-  return std::set_intersection(__left_bound_seq_1, __last1, __left_bound_seq_2, __last2, __result, __comp);
-}
-
-//------------------------------------------------------------------------
-// set_
diff erence
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
-_OutputIterator __brick_set_
diff erence(
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _OutputIterator __result,
-    _Compare __comp,
-    /*__is_vector=*/std::false_type) noexcept {
-  return std::set_
diff erence(__first1, __last1, __first2, __last2, __result, __comp);
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _RandomAccessIterator3, class _Compare>
-_RandomAccessIterator3 __brick_set_
diff erence(
-    _RandomAccessIterator1 __first1,
-    _RandomAccessIterator1 __last1,
-    _RandomAccessIterator2 __first2,
-    _RandomAccessIterator2 __last2,
-    _RandomAccessIterator3 __result,
-    _Compare __comp,
-    /*__is_vector=*/std::true_type) noexcept {
-  // TODO: vectorize
-  return std::set_
diff erence(__first1, __last1, __first2, __last2, __result, __comp);
-}
-
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _OutputIterator,
-          class _Compare>
-_OutputIterator __pattern_set_
diff erence(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _OutputIterator __result,
-    _Compare __comp) noexcept {
-  return __internal::__brick_set_
diff erence(
-      __first1, __last1, __first2, __last2, __result, __comp, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _RandomAccessIterator3,
-          class _Compare>
-_RandomAccessIterator3 __pattern_set_
diff erence(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first1,
-    _RandomAccessIterator1 __last1,
-    _RandomAccessIterator2 __first2,
-    _RandomAccessIterator2 __last2,
-    _RandomAccessIterator3 __result,
-    _Compare __comp) {
-  typedef typename std::iterator_traits<_RandomAccessIterator3>::value_type _Tp;
-  typedef typename std::iterator_traits<_RandomAccessIterator1>::
diff erence_type _DifferenceType;
-
-  const auto __n1 = __last1 - __first1;
-  const auto __n2 = __last2 - __first2;
-
-  // {} \ {2}: the 
diff erence is empty
-  if (__n1 == 0)
-    return __result;
-
-  // {1} \ {}: parallel copying just first sequence
-  if (__n2 == 0)
-    return __internal::__pattern_walk2_brick(
-        __tag,
-        std::forward<_ExecutionPolicy>(__exec),
-        __first1,
-        __last1,
-        __result,
-        [](_RandomAccessIterator1 __begin, _RandomAccessIterator1 __end, _RandomAccessIterator3 __res) {
-          return __internal::__brick_copy(__begin, __end, __res, _IsVector{});
-        });
-
-  // testing  whether the sequences are intersected
-  _RandomAccessIterator1 __left_bound_seq_1 = std::lower_bound(__first1, __last1, *__first2, __comp);
-  //{1} < {2}: seq 2 is wholly greater than seq 1, so, parallel copying just first sequence
-  if (__left_bound_seq_1 == __last1)
-    return __internal::__pattern_walk2_brick(
-        __tag,
-        std::forward<_ExecutionPolicy>(__exec),
-        __first1,
-        __last1,
-        __result,
-        [](_RandomAccessIterator1 __begin, _RandomAccessIterator1 __end, _RandomAccessIterator3 __res) {
-          return __internal::__brick_copy(__begin, __end, __res, _IsVector{});
-        });
-
-  // testing  whether the sequences are intersected
-  _RandomAccessIterator2 __left_bound_seq_2 = std::lower_bound(__first2, __last2, *__first1, __comp);
-  //{2} < {1}: seq 1 is wholly greater than seq 2, so, parallel copying just first sequence
-  if (__left_bound_seq_2 == __last2)
-    return __internal::__pattern_walk2_brick(
-        __tag,
-        std::forward<_ExecutionPolicy>(__exec),
-        __first1,
-        __last1,
-        __result,
-        [](_RandomAccessIterator1 __begin, _RandomAccessIterator1 __end, _RandomAccessIterator3 __res) {
-          return __internal::__brick_copy(__begin, __end, __res, _IsVector{});
-        });
-
-  if (__n1 + __n2 > __set_algo_cut_off)
-    return __parallel_set_op(
-        __tag,
-        std::forward<_ExecutionPolicy>(__exec),
-        __first1,
-        __last1,
-        __first2,
-        __last2,
-        __result,
-        __comp,
-        [](_DifferenceType __n, _DifferenceType) { return __n; },
-        [](_RandomAccessIterator1 __first1,
-           _RandomAccessIterator1 __last1,
-           _RandomAccessIterator2 __first2,
-           _RandomAccessIterator2 __last2,
-           _Tp* __result,
-           _Compare __comp) {
-          return __pstl::__utils::__set_
diff erence_construct(
-              __first1, __last1, __first2, __last2, __result, __comp, __BrickCopyConstruct<_IsVector>());
-        });
-
-  // use serial algorithm
-  return std::set_
diff erence(__first1, __last1, __first2, __last2, __result, __comp);
-}
-
-//------------------------------------------------------------------------
-// set_symmetric_
diff erence
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _OutputIterator, class _Compare>
-_OutputIterator __brick_set_symmetric_
diff erence(
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _OutputIterator __result,
-    _Compare __comp,
-    /*__is_vector=*/std::false_type) noexcept {
-  return std::set_symmetric_
diff erence(__first1, __last1, __first2, __last2, __result, __comp);
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _RandomAccessIterator3, class _Compare>
-_RandomAccessIterator3 __brick_set_symmetric_
diff erence(
-    _RandomAccessIterator1 __first1,
-    _RandomAccessIterator1 __last1,
-    _RandomAccessIterator2 __first2,
-    _RandomAccessIterator2 __last2,
-    _RandomAccessIterator3 __result,
-    _Compare __comp,
-    /*__is_vector=*/std::true_type) noexcept {
-  // TODO: vectorize
-  return std::set_symmetric_
diff erence(__first1, __last1, __first2, __last2, __result, __comp);
-}
-
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _OutputIterator,
-          class _Compare>
-_OutputIterator __pattern_set_symmetric_
diff erence(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _OutputIterator __result,
-    _Compare __comp) noexcept {
-  return __internal::__brick_set_symmetric_
diff erence(
-      __first1, __last1, __first2, __last2, __result, __comp, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _RandomAccessIterator3,
-          class _Compare>
-_RandomAccessIterator3 __pattern_set_symmetric_
diff erence(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first1,
-    _RandomAccessIterator1 __last1,
-    _RandomAccessIterator2 __first2,
-    _RandomAccessIterator2 __last2,
-    _RandomAccessIterator3 __result,
-    _Compare __comp) {
-  const auto __n1 = __last1 - __first1;
-  const auto __n2 = __last2 - __first2;
-
-  // use serial algorithm
-  if (__n1 + __n2 <= __set_algo_cut_off)
-    return std::set_symmetric_
diff erence(__first1, __last1, __first2, __last2, __result, __comp);
-
-  typedef typename std::iterator_traits<_RandomAccessIterator3>::value_type _Tp;
-  return __internal::__parallel_set_union_op(
-      __tag,
-      std::forward<_ExecutionPolicy>(__exec),
-      __first1,
-      __last1,
-      __first2,
-      __last2,
-      __result,
-      __comp,
-      [](_RandomAccessIterator1 __first1,
-         _RandomAccessIterator1 __last1,
-         _RandomAccessIterator2 __first2,
-         _RandomAccessIterator2 __last2,
-         _Tp* __result,
-         _Compare __comp) {
-        return __pstl::__utils::__set_symmetric_
diff erence_construct(
-            __first1, __last1, __first2, __last2, __result, __comp, __BrickCopyConstruct<_IsVector>());
-      });
-}
-
-//------------------------------------------------------------------------
-// is_heap_until
-//------------------------------------------------------------------------
-
-template <class _RandomAccessIterator, class _Compare>
-_RandomAccessIterator __brick_is_heap_until(
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _Compare __comp,
-    /* __is_vector = */ std::false_type) noexcept {
-  return std::is_heap_until(__first, __last, __comp);
-}
-
-template <class _RandomAccessIterator, class _Compare>
-_RandomAccessIterator __brick_is_heap_until(
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _Compare __comp,
-    /* __is_vector = */ std::true_type) noexcept {
-  if (__last - __first < 2)
-    return __last;
-  typedef typename std::iterator_traits<_RandomAccessIterator>::
diff erence_type _SizeType;
-  return __unseq_backend::__simd_first(
-      __first, _SizeType(0), __last - __first, [&__comp](_RandomAccessIterator __it, _SizeType __i) {
-        return __comp(__it[(__i - 1) / 2], __it[__i]);
-      });
-}
-
-template <class _Tag, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-_RandomAccessIterator __pattern_is_heap_until(
-    _Tag, _ExecutionPolicy&&, _RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) noexcept {
-  return __internal::__brick_is_heap_until(__first, __last, __comp, typename _Tag::__is_vector{});
-}
-
-template <class _RandomAccessIterator, class _DifferenceType, class _Compare>
-_RandomAccessIterator __is_heap_until_local(
-    _RandomAccessIterator __first,
-    _DifferenceType __begin,
-    _DifferenceType __end,
-    _Compare __comp,
-    /* __is_vector = */ std::false_type) noexcept {
-  _DifferenceType __i = __begin;
-  for (; __i < __end; ++__i) {
-    if (__comp(__first[(__i - 1) / 2], __first[__i])) {
-      break;
-    }
-  }
-  return __first + __i;
-}
-
-template <class _RandomAccessIterator, class _DifferenceType, class _Compare>
-_RandomAccessIterator __is_heap_until_local(
-    _RandomAccessIterator __first,
-    _DifferenceType __begin,
-    _DifferenceType __end,
-    _Compare __comp,
-    /* __is_vector = */ std::true_type) noexcept {
-  return __unseq_backend::__simd_first(
-      __first, __begin, __end, [&__comp](_RandomAccessIterator __it, _DifferenceType __i) {
-        return __comp(__it[(__i - 1) / 2], __it[__i]);
-      });
-}
-
-template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-_RandomAccessIterator __pattern_is_heap_until(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _Compare __comp) noexcept {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  if (__last - __first < 2)
-    return __last;
-
-  return __internal::__except_handler([&]() {
-    return __parallel_find(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first,
-        __last,
-        [__first, __comp](_RandomAccessIterator __i, _RandomAccessIterator __j) {
-          return __internal::__is_heap_until_local(__first, __i - __first, __j - __first, __comp, _IsVector{});
-        },
-        std::less<typename std::iterator_traits<_RandomAccessIterator>::
diff erence_type>(),
-        /*is_first=*/true);
-  });
-}
-
-//------------------------------------------------------------------------
-// min_element
-//------------------------------------------------------------------------
-
-template <typename _ForwardIterator, typename _Compare>
-_ForwardIterator __brick_min_element(
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _Compare __comp,
-    /* __is_vector = */ std::false_type) noexcept {
-  return std::min_element(__first, __last, __comp);
-}
-
-template <typename _RandomAccessIterator, typename _Compare>
-_RandomAccessIterator __brick_min_element(
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _Compare __comp,
-    /* __is_vector = */ std::true_type) noexcept {
-#if defined(_PSTL_UDR_PRESENT)
-  return __unseq_backend::__simd_min_element(__first, __last - __first, __comp);
-#else
-  return std::min_element(__first, __last, __comp);
-#endif
-}
-
-template <typename _Tag, typename _ExecutionPolicy, typename _ForwardIterator, typename _Compare>
-_ForwardIterator __pattern_min_element(
-    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Compare __comp) noexcept {
-  return __internal::__brick_min_element(__first, __last, __comp, typename _Tag::__is_vector{});
-}
-
-template <typename _IsVector, typename _ExecutionPolicy, typename _RandomAccessIterator, typename _Compare>
-_RandomAccessIterator __pattern_min_element(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _Compare __comp) {
-  if (__first == __last)
-    return __last;
-
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  return __internal::__except_handler([&]() {
-    return __par_backend::__parallel_reduce(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first + 1,
-        __last,
-        __first,
-        [=](_RandomAccessIterator __begin, _RandomAccessIterator __end, _RandomAccessIterator __init)
-            -> _RandomAccessIterator {
-          const _RandomAccessIterator subresult = __internal::__brick_min_element(__begin, __end, __comp, _IsVector{});
-          return __internal::__cmp_iterators_by_values(__init, subresult, __comp);
-        },
-        [=](_RandomAccessIterator __it1, _RandomAccessIterator __it2) -> _RandomAccessIterator {
-          return __internal::__cmp_iterators_by_values(__it1, __it2, __comp);
-        });
-  });
-}
-
-//------------------------------------------------------------------------
-// minmax_element
-//------------------------------------------------------------------------
-
-template <typename _ForwardIterator, typename _Compare>
-std::pair<_ForwardIterator, _ForwardIterator> __brick_minmax_element(
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _Compare __comp,
-    /* __is_vector = */ std::false_type) noexcept {
-  return std::minmax_element(__first, __last, __comp);
-}
-
-template <typename _RandomAccessIterator, typename _Compare>
-std::pair<_RandomAccessIterator, _RandomAccessIterator> __brick_minmax_element(
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _Compare __comp,
-    /* __is_vector = */ std::true_type) noexcept {
-#if defined(_PSTL_UDR_PRESENT)
-  return __unseq_backend::__simd_minmax_element(__first, __last - __first, __comp);
-#else
-  return std::minmax_element(__first, __last, __comp);
-#endif
-}
-
-template <typename _Tag, typename _ExecutionPolicy, typename _ForwardIterator, typename _Compare>
-std::pair<_ForwardIterator, _ForwardIterator> __pattern_minmax_element(
-    _Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Compare __comp) noexcept {
-  return __internal::__brick_minmax_element(__first, __last, __comp, typename _Tag::__is_vector{});
-}
-
-template <typename _IsVector, typename _ExecutionPolicy, typename _RandomAccessIterator, typename _Compare>
-std::pair<_RandomAccessIterator, _RandomAccessIterator> __pattern_minmax_element(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _Compare __comp) {
-  if (__first == __last)
-    return std::make_pair(__first, __first);
-
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  return __internal::__except_handler([&]() {
-    typedef std::pair<_RandomAccessIterator, _RandomAccessIterator> _Result;
-
-    return __par_backend::__parallel_reduce(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first + 1,
-        __last,
-        std::make_pair(__first, __first),
-        [=](_RandomAccessIterator __begin, _RandomAccessIterator __end, _Result __init) -> _Result {
-          const _Result __subresult = __internal::__brick_minmax_element(__begin, __end, __comp, _IsVector{});
-          return std::make_pair(
-              __internal::__cmp_iterators_by_values(__subresult.first, __init.first, __comp),
-              __internal::__cmp_iterators_by_values(__init.second, __subresult.second, std::not_fn(__comp)));
-        },
-        [=](_Result __p1, _Result __p2) -> _Result {
-          return std::make_pair(__internal::__cmp_iterators_by_values(__p1.first, __p2.first, __comp),
-                                __internal::__cmp_iterators_by_values(__p2.second, __p1.second, std::not_fn(__comp)));
-        });
-  });
-}
-
-//------------------------------------------------------------------------
-// mismatch
-//------------------------------------------------------------------------
-template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-std::pair<_ForwardIterator1, _ForwardIterator2> __mismatch_serial(
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _BinaryPredicate __pred) {
-  return std::mismatch(__first1, __last1, __first2, __last2, __pred);
-}
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _Predicate>
-std::pair<_ForwardIterator1, _ForwardIterator2> __brick_mismatch(
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _Predicate __pred,
-    /* __is_vector = */ std::false_type) noexcept {
-  return __mismatch_serial(__first1, __last1, __first2, __last2, __pred);
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _Predicate>
-std::pair<_RandomAccessIterator1, _RandomAccessIterator2> __brick_mismatch(
-    _RandomAccessIterator1 __first1,
-    _RandomAccessIterator1 __last1,
-    _RandomAccessIterator2 __first2,
-    _RandomAccessIterator2 __last2,
-    _Predicate __pred,
-    /* __is_vector = */ std::true_type) noexcept {
-  auto __n = std::min(__last1 - __first1, __last2 - __first2);
-  return __unseq_backend::__simd_first(__first1, __n, __first2, std::not_fn(__pred));
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Predicate>
-std::pair<_ForwardIterator1, _ForwardIterator2> __pattern_mismatch(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _Predicate __pred) noexcept {
-  return __internal::__brick_mismatch(__first1, __last1, __first2, __last2, __pred, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _Predicate>
-std::pair<_RandomAccessIterator1, _RandomAccessIterator2> __pattern_mismatch(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first1,
-    _RandomAccessIterator1 __last1,
-    _RandomAccessIterator2 __first2,
-    _RandomAccessIterator2 __last2,
-    _Predicate __pred) noexcept {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  return __internal::__except_handler([&]() {
-    auto __n      = std::min(__last1 - __first1, __last2 - __first2);
-    auto __result = __internal::__parallel_find(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first1,
-        __first1 + __n,
-        [__first1, __first2, __pred](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
-          return __internal::__brick_mismatch(
-                     __i, __j, __first2 + (__i - __first1), __first2 + (__j - __first1), __pred, _IsVector{})
-              .first;
-        },
-        std::less<typename std::iterator_traits<_RandomAccessIterator1>::
diff erence_type>(),
-        /*is_first=*/true);
-    return std::make_pair(__result, __first2 + (__result - __first1));
-  });
-}
-
-//------------------------------------------------------------------------
-// lexicographical_compare
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _Compare>
-bool __brick_lexicographical_compare(
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _Compare __comp,
-    /* __is_vector = */ std::false_type) noexcept {
-  return std::lexicographical_compare(__first1, __last1, __first2, __last2, __comp);
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _Compare>
-bool __brick_lexicographical_compare(
-    _RandomAccessIterator1 __first1,
-    _RandomAccessIterator1 __last1,
-    _RandomAccessIterator2 __first2,
-    _RandomAccessIterator2 __last2,
-    _Compare __comp,
-    /* __is_vector = */ std::true_type) noexcept {
-  if (__first2 == __last2) { // if second sequence is empty
-    return false;
-  } else if (__first1 == __last1) { // if first sequence is empty
-    return true;
-  } else {
-    typedef typename std::iterator_traits<_RandomAccessIterator1>::reference ref_type1;
-    typedef typename std::iterator_traits<_RandomAccessIterator2>::reference ref_type2;
-    --__last1;
-    --__last2;
-    auto __n = std::min(__last1 - __first1, __last2 - __first2);
-    std::pair<_RandomAccessIterator1, _RandomAccessIterator2> __result = __unseq_backend::__simd_first(
-        __first1, __n, __first2, [__comp](const ref_type1 __x, const ref_type2 __y) mutable {
-          return __comp(__x, __y) || __comp(__y, __x);
-        });
-
-    if (__result.first == __last1 && __result.second != __last2) { // if first sequence shorter than second
-      return !__comp(*__result.second, *__result.first);
-    } else { // if second sequence shorter than first or both have the same number of elements
-      return __comp(*__result.first, *__result.second);
-    }
-  }
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Compare>
-bool __pattern_lexicographical_compare(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _Compare __comp) noexcept {
-  return __internal::__brick_lexicographical_compare(
-      __first1, __last1, __first2, __last2, __comp, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _Compare>
-bool __pattern_lexicographical_compare(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first1,
-    _RandomAccessIterator1 __last1,
-    _RandomAccessIterator2 __first2,
-    _RandomAccessIterator2 __last2,
-    _Compare __comp) noexcept {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  if (__first2 == __last2) { // if second sequence is empty
-    return false;
-  } else if (__first1 == __last1) { // if first sequence is empty
-    return true;
-  } else {
-    typedef typename std::iterator_traits<_RandomAccessIterator1>::reference _RefType1;
-    typedef typename std::iterator_traits<_RandomAccessIterator2>::reference _RefType2;
-    --__last1;
-    --__last2;
-    auto __n      = std::min(__last1 - __first1, __last2 - __first2);
-    auto __result = __internal::__parallel_find(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __first1,
-        __first1 + __n,
-        [__first1, __first2, &__comp](_RandomAccessIterator1 __i, _RandomAccessIterator1 __j) {
-          return __internal::__brick_mismatch(
-                     __i,
-                     __j,
-                     __first2 + (__i - __first1),
-                     __first2 + (__j - __first1),
-                     [&__comp](const _RefType1 __x, const _RefType2 __y) {
-                       return !__comp(__x, __y) && !__comp(__y, __x);
-                     },
-                     _IsVector{})
-              .first;
-        },
-        std::less<typename std::iterator_traits<_RandomAccessIterator1>::
diff erence_type>(),
-        /*is_first=*/true);
-
-    if (__result == __last1 && __first2 + (__result - __first1) != __last2) { // if first sequence shorter than second
-      return !__comp(*(__first2 + (__result - __first1)), *__result);
-    } else { // if second sequence shorter than first or both have the same number of elements
-      return __comp(*__result, *(__first2 + (__result - __first1)));
-    }
-  }
-}
-
-} // namespace __internal
-} // namespace __pstl
-
-#endif /* _PSTL_ALGORITHM_IMPL_H */

diff  --git a/libcxx/include/__pstl/internal/execution_defs.h b/libcxx/include/__pstl/internal/execution_defs.h
deleted file mode 100644
index 5992f0e4a37510..00000000000000
--- a/libcxx/include/__pstl/internal/execution_defs.h
+++ /dev/null
@@ -1,76 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_EXECUTION_POLICY_DEFS_H
-#define _PSTL_EXECUTION_POLICY_DEFS_H
-
-#include <__config>
-#include <__type_traits/decay.h>
-#include <__type_traits/enable_if.h>
-#include <__type_traits/integral_constant.h>
-
-#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
-namespace __pstl {
-namespace execution {
-inline namespace v1 {
-
-// 2.4, Sequential execution policy
-class sequenced_policy {};
-
-// 2.5, Parallel execution policy
-class parallel_policy {};
-
-// 2.6, Parallel+Vector execution policy
-class parallel_unsequenced_policy {};
-
-class unsequenced_policy {};
-
-// 2.8, Execution policy objects
-constexpr sequenced_policy seq{};
-constexpr parallel_policy par{};
-constexpr parallel_unsequenced_policy par_unseq{};
-constexpr unsequenced_policy unseq{};
-
-// 2.3, Execution policy type trait
-template <class>
-struct is_execution_policy : std::false_type {};
-
-template <>
-struct is_execution_policy<__pstl::execution::sequenced_policy> : std::true_type {};
-template <>
-struct is_execution_policy<__pstl::execution::parallel_policy> : std::true_type {};
-template <>
-struct is_execution_policy<__pstl::execution::parallel_unsequenced_policy> : std::true_type {};
-template <>
-struct is_execution_policy<__pstl::execution::unsequenced_policy> : std::true_type {};
-
-template <class _Tp>
-constexpr bool is_execution_policy_v = __pstl::execution::is_execution_policy<_Tp>::value;
-} // namespace v1
-} // namespace execution
-
-namespace __internal {
-template <class _ExecPolicy, class _Tp>
-using __enable_if_execution_policy =
-    typename std::enable_if<__pstl::execution::is_execution_policy<typename std::decay<_ExecPolicy>::type>::value,
-                            _Tp>::type;
-
-template <class _IsVector>
-struct __serial_tag;
-template <class _IsVector>
-struct __parallel_tag;
-
-} // namespace __internal
-
-} // namespace __pstl
-
-#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
-#endif /* _PSTL_EXECUTION_POLICY_DEFS_H */

diff  --git a/libcxx/include/__pstl/internal/execution_impl.h b/libcxx/include/__pstl/internal/execution_impl.h
deleted file mode 100644
index c3a7405d393f1d..00000000000000
--- a/libcxx/include/__pstl/internal/execution_impl.h
+++ /dev/null
@@ -1,97 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_EXECUTION_IMPL_H
-#define _PSTL_EXECUTION_IMPL_H
-
-#include <__config>
-#include <__iterator/iterator_traits.h>
-#include <__type_traits/conditional.h>
-#include <__type_traits/conjunction.h>
-#include <__type_traits/decay.h>
-#include <__type_traits/integral_constant.h>
-#include <__type_traits/is_base_of.h>
-
-#include <__pstl/internal/execution_defs.h>
-
-#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
-namespace __pstl {
-namespace __internal {
-
-template <typename _IteratorTag, typename... _IteratorTypes>
-using __are_iterators_of = std::conjunction<
-    std::is_base_of<_IteratorTag, typename std::iterator_traits<std::decay_t<_IteratorTypes>>::iterator_category>...>;
-
-template <typename... _IteratorTypes>
-using __are_random_access_iterators = __are_iterators_of<std::random_access_iterator_tag, _IteratorTypes...>;
-
-struct __serial_backend_tag {};
-struct __tbb_backend_tag {};
-struct __openmp_backend_tag {};
-
-#  if defined(_PSTL_PAR_BACKEND_TBB)
-using __par_backend_tag = __tbb_backend_tag;
-#  elif defined(_PSTL_PAR_BACKEND_OPENMP)
-using __par_backend_tag = __openmp_backend_tag;
-#  elif defined(_PSTL_PAR_BACKEND_SERIAL)
-using __par_backend_tag = __serial_backend_tag;
-#  else
-#    error "A parallel backend must be specified";
-#  endif
-
-template <class _IsVector>
-struct __serial_tag {
-  using __is_vector = _IsVector;
-};
-
-template <class _IsVector>
-struct __parallel_tag {
-  using __is_vector = _IsVector;
-  // backend tag can be change depending on
-  // TBB availability in the environment
-  using __backend_tag = __par_backend_tag;
-};
-
-template <class _IsVector, class... _IteratorTypes>
-using __tag_type =
-    typename std::conditional<__internal::__are_random_access_iterators<_IteratorTypes...>::value,
-                              __parallel_tag<_IsVector>,
-                              __serial_tag<_IsVector>>::type;
-
-template <class... _IteratorTypes>
-_LIBCPP_HIDE_FROM_ABI __serial_tag</*_IsVector = */ std::false_type>
-__select_backend(__pstl::execution::sequenced_policy, _IteratorTypes&&...) {
-  return {};
-}
-
-template <class... _IteratorTypes>
-_LIBCPP_HIDE_FROM_ABI __serial_tag<__internal::__are_random_access_iterators<_IteratorTypes...>>
-__select_backend(__pstl::execution::unsequenced_policy, _IteratorTypes&&...) {
-  return {};
-}
-
-template <class... _IteratorTypes>
-_LIBCPP_HIDE_FROM_ABI __tag_type</*_IsVector = */ std::false_type, _IteratorTypes...>
-__select_backend(__pstl::execution::parallel_policy, _IteratorTypes&&...) {
-  return {};
-}
-
-template <class... _IteratorTypes>
-_LIBCPP_HIDE_FROM_ABI __tag_type<__internal::__are_random_access_iterators<_IteratorTypes...>, _IteratorTypes...>
-__select_backend(__pstl::execution::parallel_unsequenced_policy, _IteratorTypes&&...) {
-  return {};
-}
-
-} // namespace __internal
-} // namespace __pstl
-
-#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
-#endif /* _PSTL_EXECUTION_IMPL_H */

diff  --git a/libcxx/include/__pstl/internal/glue_algorithm_defs.h b/libcxx/include/__pstl/internal/glue_algorithm_defs.h
deleted file mode 100644
index 00458d5ffbbdb9..00000000000000
--- a/libcxx/include/__pstl/internal/glue_algorithm_defs.h
+++ /dev/null
@@ -1,655 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_GLUE_ALGORITHM_DEFS_H
-#define _PSTL_GLUE_ALGORITHM_DEFS_H
-
-#include <__config>
-#include <functional>
-#include <iterator>
-
-#include "execution_defs.h"
-
-namespace std {
-
-// [alg.find.end]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator1>
-find_end(_ExecutionPolicy&& __exec,
-         _ForwardIterator1 __first,
-         _ForwardIterator1 __last,
-         _ForwardIterator2 __s_first,
-         _ForwardIterator2 __s_last,
-         _BinaryPredicate __pred);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator1>
-find_end(_ExecutionPolicy&& __exec,
-         _ForwardIterator1 __first,
-         _ForwardIterator1 __last,
-         _ForwardIterator2 __s_first,
-         _ForwardIterator2 __s_last);
-
-// [alg.find_first_of]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator1> find_first_of(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __s_first,
-    _ForwardIterator2 __s_last,
-    _BinaryPredicate __pred);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator1>
-find_first_of(_ExecutionPolicy&& __exec,
-              _ForwardIterator1 __first,
-              _ForwardIterator1 __last,
-              _ForwardIterator2 __s_first,
-              _ForwardIterator2 __s_last);
-
-// [alg.adjacent_find]
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-adjacent_find(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last);
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-adjacent_find(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred);
-
-// [alg.count]
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Tp>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy,
-                                                 typename iterator_traits<_ForwardIterator>::
diff erence_type>
-count(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value);
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Predicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy,
-                                                 typename iterator_traits<_ForwardIterator>::
diff erence_type>
-count_if(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Predicate __pred);
-
-// [alg.search]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator1>
-search(_ExecutionPolicy&& __exec,
-       _ForwardIterator1 __first,
-       _ForwardIterator1 __last,
-       _ForwardIterator2 __s_first,
-       _ForwardIterator2 __s_last,
-       _BinaryPredicate __pred);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator1>
-search(_ExecutionPolicy&& __exec,
-       _ForwardIterator1 __first,
-       _ForwardIterator1 __last,
-       _ForwardIterator2 __s_first,
-       _ForwardIterator2 __s_last);
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-search_n(_ExecutionPolicy&& __exec,
-         _ForwardIterator __first,
-         _ForwardIterator __last,
-         _Size __count,
-         const _Tp& __value,
-         _BinaryPredicate __pred);
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Size, class _Tp>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator> search_n(
-    _ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Size __count, const _Tp& __value);
-
-// [alg.copy]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Predicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2>
-copy_if(_ExecutionPolicy&& __exec,
-        _ForwardIterator1 __first,
-        _ForwardIterator1 __last,
-        _ForwardIterator2 result,
-        _Predicate __pred);
-
-// [alg.swap]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> swap_ranges(
-    _ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2);
-
-// [alg.replace]
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate, class _Tp>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-replace_if(_ExecutionPolicy&& __exec,
-           _ForwardIterator __first,
-           _ForwardIterator __last,
-           _UnaryPredicate __pred,
-           const _Tp& __new_value);
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Tp>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-replace(_ExecutionPolicy&& __exec,
-        _ForwardIterator __first,
-        _ForwardIterator __last,
-        const _Tp& __old_value,
-        const _Tp& __new_value);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _UnaryPredicate, class _Tp>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> replace_copy_if(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __result,
-    _UnaryPredicate __pred,
-    const _Tp& __new_value);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Tp>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> replace_copy(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __result,
-    const _Tp& __old_value,
-    const _Tp& __new_value);
-
-// [alg.generate]
-template <class _ExecutionPolicy, class _ForwardIterator, class _Generator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-generate(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Generator __g);
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Size, class _Generator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-generate_n(_ExecutionPolicy&& __exec, _ForwardIterator __first, _Size count, _Generator __g);
-
-// [alg.remove]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Predicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> remove_copy_if(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __result,
-    _Predicate __pred);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Tp>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2>
-remove_copy(_ExecutionPolicy&& __exec,
-            _ForwardIterator1 __first,
-            _ForwardIterator1 __last,
-            _ForwardIterator2 __result,
-            const _Tp& __value);
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-remove_if(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _UnaryPredicate __pred);
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Tp>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-remove(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value);
-
-// [alg.unique]
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-unique(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred);
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-unique(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2>
-unique_copy(_ExecutionPolicy&& __exec,
-            _ForwardIterator1 __first,
-            _ForwardIterator1 __last,
-            _ForwardIterator2 __result,
-            _BinaryPredicate __pred);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2>
-unique_copy(_ExecutionPolicy&& __exec, _ForwardIterator1 __first, _ForwardIterator1 __last, _ForwardIterator2 __result);
-
-// [alg.reverse]
-
-template <class _ExecutionPolicy, class _BidirectionalIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-reverse(_ExecutionPolicy&& __exec, _BidirectionalIterator __first, _BidirectionalIterator __last);
-
-template <class _ExecutionPolicy, class _BidirectionalIterator, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-reverse_copy(_ExecutionPolicy&& __exec,
-             _BidirectionalIterator __first,
-             _BidirectionalIterator __last,
-             _ForwardIterator __d_first);
-
-// [alg.rotate]
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-rotate(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2>
-rotate_copy(_ExecutionPolicy&& __exec,
-            _ForwardIterator1 __first,
-            _ForwardIterator1 __middle,
-            _ForwardIterator1 __last,
-            _ForwardIterator2 __result);
-
-// [alg.partitions]
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-is_partitioned(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _UnaryPredicate __pred);
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-partition(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _UnaryPredicate __pred);
-
-template <class _ExecutionPolicy, class _BidirectionalIterator, class _UnaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _BidirectionalIterator> stable_partition(
-    _ExecutionPolicy&& __exec, _BidirectionalIterator __first, _BidirectionalIterator __last, _UnaryPredicate __pred);
-
-template <class _ExecutionPolicy,
-          class _ForwardIterator,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _UnaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, std::pair<_ForwardIterator1, _ForwardIterator2>>
-partition_copy(_ExecutionPolicy&& __exec,
-               _ForwardIterator __first,
-               _ForwardIterator __last,
-               _ForwardIterator1 __out_true,
-               _ForwardIterator2 __out_false,
-               _UnaryPredicate __pred);
-
-// [alg.sort]
-
-template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-sort(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp);
-
-template <class _ExecutionPolicy, class _RandomAccessIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-sort(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last);
-
-// [stable.sort]
-
-template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-stable_sort(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp);
-
-template <class _ExecutionPolicy, class _RandomAccessIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-stable_sort(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last);
-
-// [mismatch]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, std::pair<_ForwardIterator1, _ForwardIterator2>>
-mismatch(_ExecutionPolicy&& __exec,
-         _ForwardIterator1 __first1,
-         _ForwardIterator1 __last1,
-         _ForwardIterator2 __first2,
-         _ForwardIterator2 __last2,
-         _BinaryPredicate __pred);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, std::pair<_ForwardIterator1, _ForwardIterator2>>
-mismatch(_ExecutionPolicy&& __exec,
-         _ForwardIterator1 __first1,
-         _ForwardIterator1 __last1,
-         _ForwardIterator2 __first2,
-         _BinaryPredicate __pred);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, std::pair<_ForwardIterator1, _ForwardIterator2>>
-mismatch(_ExecutionPolicy&& __exec,
-         _ForwardIterator1 __first1,
-         _ForwardIterator1 __last1,
-         _ForwardIterator2 __first2,
-         _ForwardIterator2 __last2);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, std::pair<_ForwardIterator1, _ForwardIterator2>>
-mismatch(_ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2);
-
-// [alg.equal]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-equal(_ExecutionPolicy&& __exec,
-      _ForwardIterator1 __first1,
-      _ForwardIterator1 __last1,
-      _ForwardIterator2 __first2,
-      _BinaryPredicate __p);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-equal(_ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-equal(_ExecutionPolicy&& __exec,
-      _ForwardIterator1 __first1,
-      _ForwardIterator1 __last1,
-      _ForwardIterator2 __first2,
-      _ForwardIterator2 __last2,
-      _BinaryPredicate __p);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-equal(_ExecutionPolicy&& __exec,
-      _ForwardIterator1 __first1,
-      _ForwardIterator1 __last1,
-      _ForwardIterator2 __first2,
-      _ForwardIterator2 __last2);
-
-// [alg.move]
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2>
-move(_ExecutionPolicy&& __exec, _ForwardIterator1 __first, _ForwardIterator1 __last, _ForwardIterator2 __d_first);
-
-// [partial.sort]
-
-template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-partial_sort(_ExecutionPolicy&& __exec,
-             _RandomAccessIterator __first,
-             _RandomAccessIterator __middle,
-             _RandomAccessIterator __last,
-             _Compare __comp);
-
-template <class _ExecutionPolicy, class _RandomAccessIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-partial_sort(_ExecutionPolicy&& __exec,
-             _RandomAccessIterator __first,
-             _RandomAccessIterator __middle,
-             _RandomAccessIterator __last);
-
-// [partial.sort.copy]
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _RandomAccessIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _RandomAccessIterator> partial_sort_copy(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _RandomAccessIterator __d_first,
-    _RandomAccessIterator __d_last,
-    _Compare __comp);
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _RandomAccessIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _RandomAccessIterator> partial_sort_copy(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _RandomAccessIterator __d_first,
-    _RandomAccessIterator __d_last);
-
-// [is.sorted]
-template <class _ExecutionPolicy, class _ForwardIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-is_sorted_until(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Compare __comp);
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-is_sorted_until(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last);
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-is_sorted(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Compare __comp);
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-is_sorted(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last);
-
-// [alg.nth.element]
-
-template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-nth_element(_ExecutionPolicy&& __exec,
-            _RandomAccessIterator __first,
-            _RandomAccessIterator __nth,
-            _RandomAccessIterator __last,
-            _Compare __comp);
-
-template <class _ExecutionPolicy, class _RandomAccessIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-nth_element(_ExecutionPolicy&& __exec,
-            _RandomAccessIterator __first,
-            _RandomAccessIterator __nth,
-            _RandomAccessIterator __last);
-
-// [alg.merge]
-template <class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _ForwardIterator,
-          class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-merge(_ExecutionPolicy&& __exec,
-      _ForwardIterator1 __first1,
-      _ForwardIterator1 __last1,
-      _ForwardIterator2 __first2,
-      _ForwardIterator2 __last2,
-      _ForwardIterator __d_first,
-      _Compare __comp);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-merge(_ExecutionPolicy&& __exec,
-      _ForwardIterator1 __first1,
-      _ForwardIterator1 __last1,
-      _ForwardIterator2 __first2,
-      _ForwardIterator2 __last2,
-      _ForwardIterator __d_first);
-
-template <class _ExecutionPolicy, class _BidirectionalIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-inplace_merge(_ExecutionPolicy&& __exec,
-              _BidirectionalIterator __first,
-              _BidirectionalIterator __middle,
-              _BidirectionalIterator __last,
-              _Compare __comp);
-
-template <class _ExecutionPolicy, class _BidirectionalIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-inplace_merge(_ExecutionPolicy&& __exec,
-              _BidirectionalIterator __first,
-              _BidirectionalIterator __middle,
-              _BidirectionalIterator __last);
-
-// [includes]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-includes(_ExecutionPolicy&& __exec,
-         _ForwardIterator1 __first1,
-         _ForwardIterator1 __last1,
-         _ForwardIterator2 __first2,
-         _ForwardIterator2 __last2,
-         _Compare __comp);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-includes(_ExecutionPolicy&& __exec,
-         _ForwardIterator1 __first1,
-         _ForwardIterator1 __last1,
-         _ForwardIterator2 __first2,
-         _ForwardIterator2 __last2);
-
-// [set.union]
-
-template <class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _ForwardIterator,
-          class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-set_union(_ExecutionPolicy&& __exec,
-          _ForwardIterator1 __first1,
-          _ForwardIterator1 __last1,
-          _ForwardIterator2 __first2,
-          _ForwardIterator2 __last2,
-          _ForwardIterator __result,
-          _Compare __comp);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-set_union(_ExecutionPolicy&& __exec,
-          _ForwardIterator1 __first1,
-          _ForwardIterator1 __last1,
-          _ForwardIterator2 __first2,
-          _ForwardIterator2 __last2,
-          _ForwardIterator __result);
-
-// [set.intersection]
-
-template <class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _ForwardIterator,
-          class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator> set_intersection(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _ForwardIterator __result,
-    _Compare __comp);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator> set_intersection(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _ForwardIterator __result);
-
-// [set.
diff erence]
-
-template <class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _ForwardIterator,
-          class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator> set_
diff erence(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _ForwardIterator __result,
-    _Compare __comp);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator> set_
diff erence(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _ForwardIterator __result);
-
-// [set.symmetric.
diff erence]
-
-template <class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _ForwardIterator,
-          class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator> set_symmetric_
diff erence(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _ForwardIterator result,
-    _Compare __comp);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator> set_symmetric_
diff erence(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _ForwardIterator __result);
-
-// [is.heap]
-template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _RandomAccessIterator>
-is_heap_until(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp);
-
-template <class _ExecutionPolicy, class _RandomAccessIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _RandomAccessIterator>
-is_heap_until(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last);
-
-template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-is_heap(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp);
-
-template <class _ExecutionPolicy, class _RandomAccessIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-is_heap(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last);
-
-// [alg.min.max]
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-min_element(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Compare __comp);
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-min_element(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last);
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-max_element(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Compare __comp);
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-max_element(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last);
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, std::pair<_ForwardIterator, _ForwardIterator>>
-minmax_element(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Compare __comp);
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, std::pair<_ForwardIterator, _ForwardIterator>>
-minmax_element(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last);
-
-// [alg.lex.comparison]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool> lexicographical_compare(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _Compare __comp);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool> lexicographical_compare(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2);
-
-} // namespace std
-
-#endif /* _PSTL_GLUE_ALGORITHM_DEFS_H */

diff  --git a/libcxx/include/__pstl/internal/glue_algorithm_impl.h b/libcxx/include/__pstl/internal/glue_algorithm_impl.h
deleted file mode 100644
index 8e8f2539f859f2..00000000000000
--- a/libcxx/include/__pstl/internal/glue_algorithm_impl.h
+++ /dev/null
@@ -1,972 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_GLUE_ALGORITHM_IMPL_H
-#define _PSTL_GLUE_ALGORITHM_IMPL_H
-
-#include <__config>
-#include <functional>
-
-#include "algorithm_fwd.h"
-#include "execution_defs.h"
-#include "numeric_fwd.h" /* count and count_if use __pattern_transform_reduce */
-#include "utils.h"
-
-#include "execution_impl.h"
-
-namespace std {
-
-// [alg.find.end]
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator1>
-find_end(_ExecutionPolicy&& __exec,
-         _ForwardIterator1 __first,
-         _ForwardIterator1 __last,
-         _ForwardIterator2 __s_first,
-         _ForwardIterator2 __s_last,
-         _BinaryPredicate __pred) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __s_first);
-
-  return __pstl::__internal::__pattern_find_end(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __s_first, __s_last, __pred);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator1>
-find_end(_ExecutionPolicy&& __exec,
-         _ForwardIterator1 __first,
-         _ForwardIterator1 __last,
-         _ForwardIterator2 __s_first,
-         _ForwardIterator2 __s_last) {
-  return std::find_end(std::forward<_ExecutionPolicy>(__exec), __first, __last, __s_first, __s_last, std::equal_to<>());
-}
-
-// [alg.find_first_of]
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator1> find_first_of(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __s_first,
-    _ForwardIterator2 __s_last,
-    _BinaryPredicate __pred) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __s_first);
-
-  return __pstl::__internal::__pattern_find_first_of(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __s_first, __s_last, __pred);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator1>
-find_first_of(_ExecutionPolicy&& __exec,
-              _ForwardIterator1 __first,
-              _ForwardIterator1 __last,
-              _ForwardIterator2 __s_first,
-              _ForwardIterator2 __s_last) {
-  return std::find_first_of(
-      std::forward<_ExecutionPolicy>(__exec), __first, __last, __s_first, __s_last, std::equal_to<>());
-}
-
-// [alg.adjacent_find]
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-adjacent_find(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  typedef typename iterator_traits<_ForwardIterator>::value_type _ValueType;
-  return __pstl::__internal::__pattern_adjacent_find(
-      __dispatch_tag,
-      std::forward<_ExecutionPolicy>(__exec),
-      __first,
-      __last,
-      std::equal_to<_ValueType>(),
-      /*first_semantic*/ false);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-adjacent_find(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-  return __pstl::__internal::__pattern_adjacent_find(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __pred, /*first_semantic*/ false);
-}
-
-// [alg.count]
-
-// Implementation note: count and count_if call the pattern directly instead of calling std::transform_reduce
-// so that we do not have to include <numeric>.
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Tp>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy,
-                                                 typename iterator_traits<_ForwardIterator>::
diff erence_type>
-count(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  typedef typename iterator_traits<_ForwardIterator>::value_type _ValueType;
-  return __pstl::__internal::__pattern_count(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, [&__value](const _ValueType& __x) {
-        return __value == __x;
-      });
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Predicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy,
-                                                 typename iterator_traits<_ForwardIterator>::
diff erence_type>
-count_if(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Predicate __pred) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-  return __pstl::__internal::__pattern_count(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __pred);
-}
-
-// [alg.search]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator1>
-search(_ExecutionPolicy&& __exec,
-       _ForwardIterator1 __first,
-       _ForwardIterator1 __last,
-       _ForwardIterator2 __s_first,
-       _ForwardIterator2 __s_last,
-       _BinaryPredicate __pred) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __s_first);
-
-  return __pstl::__internal::__pattern_search(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __s_first, __s_last, __pred);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator1>
-search(_ExecutionPolicy&& __exec,
-       _ForwardIterator1 __first,
-       _ForwardIterator1 __last,
-       _ForwardIterator2 __s_first,
-       _ForwardIterator2 __s_last) {
-  return std::search(std::forward<_ExecutionPolicy>(__exec), __first, __last, __s_first, __s_last, std::equal_to<>());
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-search_n(_ExecutionPolicy&& __exec,
-         _ForwardIterator __first,
-         _ForwardIterator __last,
-         _Size __count,
-         const _Tp& __value,
-         _BinaryPredicate __pred) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  return __pstl::__internal::__pattern_search_n(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __count, __value, __pred);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Size, class _Tp>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator> search_n(
-    _ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Size __count, const _Tp& __value) {
-  return std::search_n(
-      std::forward<_ExecutionPolicy>(__exec),
-      __first,
-      __last,
-      __count,
-      __value,
-      std::equal_to<typename iterator_traits<_ForwardIterator>::value_type>());
-}
-
-// [alg.copy]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Predicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2>
-copy_if(_ExecutionPolicy&& __exec,
-        _ForwardIterator1 __first,
-        _ForwardIterator1 __last,
-        _ForwardIterator2 __result,
-        _Predicate __pred) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __result);
-
-  return __pstl::__internal::__pattern_copy_if(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __result, __pred);
-}
-
-// [alg.swap]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> swap_ranges(
-    _ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2) {
-  typedef typename iterator_traits<_ForwardIterator1>::reference _ReferenceType1;
-  typedef typename iterator_traits<_ForwardIterator2>::reference _ReferenceType2;
-
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first1, __first2);
-
-  return __pstl::__internal::__pattern_walk2(
-      __dispatch_tag,
-      std::forward<_ExecutionPolicy>(__exec),
-      __first1,
-      __last1,
-      __first2,
-      [](_ReferenceType1 __x, _ReferenceType2 __y) {
-        using std::swap;
-        swap(__x, __y);
-      });
-}
-
-// [alg.generate]
-template <class _ExecutionPolicy, class _ForwardIterator, class _Generator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-generate(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Generator __g) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  __pstl::__internal::__pattern_generate(__dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __g);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Size, class _Generator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-generate_n(_ExecutionPolicy&& __exec, _ForwardIterator __first, _Size __count, _Generator __g) {
-  if (__count <= 0)
-    return __first;
-
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  return __pstl::__internal::__pattern_generate_n(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __count, __g);
-}
-
-// [alg.remove]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Predicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> remove_copy_if(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __result,
-    _Predicate __pred) {
-  return std::copy_if(std::forward<_ExecutionPolicy>(__exec), __first, __last, __result, std::not_fn(__pred));
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Tp>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2>
-remove_copy(_ExecutionPolicy&& __exec,
-            _ForwardIterator1 __first,
-            _ForwardIterator1 __last,
-            _ForwardIterator2 __result,
-            const _Tp& __value) {
-  return std::copy_if(
-      std::forward<_ExecutionPolicy>(__exec),
-      __first,
-      __last,
-      __result,
-      __pstl::__internal::__not_equal_value<_Tp>(__value));
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-remove_if(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _UnaryPredicate __pred) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  return __pstl::__internal::__pattern_remove_if(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __pred);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Tp>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-remove(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value) {
-  return std::remove_if(
-      std::forward<_ExecutionPolicy>(__exec), __first, __last, __pstl::__internal::__equal_value<_Tp>(__value));
-}
-
-// [alg.unique]
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-unique(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  return __pstl::__internal::__pattern_unique(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __pred);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-unique(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last) {
-  return std::unique(std::forward<_ExecutionPolicy>(__exec), __first, __last, std::equal_to<>());
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2>
-unique_copy(_ExecutionPolicy&& __exec,
-            _ForwardIterator1 __first,
-            _ForwardIterator1 __last,
-            _ForwardIterator2 __result,
-            _BinaryPredicate __pred) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __result);
-
-  return __pstl::__internal::__pattern_unique_copy(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __result, __pred);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> unique_copy(
-    _ExecutionPolicy&& __exec, _ForwardIterator1 __first, _ForwardIterator1 __last, _ForwardIterator2 __result) {
-  return std::unique_copy(__exec, __first, __last, __result, std::equal_to<>());
-}
-
-// [alg.reverse]
-
-template <class _ExecutionPolicy, class _BidirectionalIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-reverse(_ExecutionPolicy&& __exec, _BidirectionalIterator __first, _BidirectionalIterator __last) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  __pstl::__internal::__pattern_reverse(__dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last);
-}
-
-template <class _ExecutionPolicy, class _BidirectionalIterator, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-reverse_copy(_ExecutionPolicy&& __exec,
-             _BidirectionalIterator __first,
-             _BidirectionalIterator __last,
-             _ForwardIterator __d_first) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __d_first);
-
-  return __pstl::__internal::__pattern_reverse_copy(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __d_first);
-}
-
-// [alg.rotate]
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-rotate(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  return __pstl::__internal::__pattern_rotate(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __middle, __last);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2>
-rotate_copy(_ExecutionPolicy&& __exec,
-            _ForwardIterator1 __first,
-            _ForwardIterator1 __middle,
-            _ForwardIterator1 __last,
-            _ForwardIterator2 __result) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __result);
-
-  return __pstl::__internal::__pattern_rotate_copy(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __middle, __last, __result);
-}
-
-// [alg.partitions]
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-is_partitioned(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _UnaryPredicate __pred) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-  return __pstl::__internal::__pattern_is_partitioned(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __pred);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _UnaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-partition(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _UnaryPredicate __pred) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  return __pstl::__internal::__pattern_partition(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __pred);
-}
-
-template <class _ExecutionPolicy, class _BidirectionalIterator, class _UnaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _BidirectionalIterator> stable_partition(
-    _ExecutionPolicy&& __exec, _BidirectionalIterator __first, _BidirectionalIterator __last, _UnaryPredicate __pred) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-  return __pstl::__internal::__pattern_stable_partition(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __pred);
-}
-
-template <class _ExecutionPolicy,
-          class _ForwardIterator,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _UnaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, std::pair<_ForwardIterator1, _ForwardIterator2>>
-partition_copy(_ExecutionPolicy&& __exec,
-               _ForwardIterator __first,
-               _ForwardIterator __last,
-               _ForwardIterator1 __out_true,
-               _ForwardIterator2 __out_false,
-               _UnaryPredicate __pred) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __out_true, __out_false);
-
-  return __pstl::__internal::__pattern_partition_copy(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __out_true, __out_false, __pred);
-}
-
-// [alg.sort]
-
-template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-sort(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  typedef typename iterator_traits<_RandomAccessIterator>::value_type _InputType;
-  return __pstl::__internal::__pattern_sort(
-      __dispatch_tag,
-      std::forward<_ExecutionPolicy>(__exec),
-      __first,
-      __last,
-      __comp,
-      typename std::is_move_constructible<_InputType>::type());
-}
-
-template <class _ExecutionPolicy, class _RandomAccessIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-sort(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last) {
-  typedef typename std::iterator_traits<_RandomAccessIterator>::value_type _InputType;
-  std::sort(std::forward<_ExecutionPolicy>(__exec), __first, __last, std::less<_InputType>());
-}
-
-// [stable.sort]
-
-template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-stable_sort(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  return __pstl::__internal::__pattern_stable_sort(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __comp);
-}
-
-template <class _ExecutionPolicy, class _RandomAccessIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-stable_sort(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last) {
-  typedef typename std::iterator_traits<_RandomAccessIterator>::value_type _InputType;
-  std::stable_sort(__exec, __first, __last, std::less<_InputType>());
-}
-
-// [mismatch]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, std::pair<_ForwardIterator1, _ForwardIterator2>>
-mismatch(_ExecutionPolicy&& __exec,
-         _ForwardIterator1 __first1,
-         _ForwardIterator1 __last1,
-         _ForwardIterator2 __first2,
-         _ForwardIterator2 __last2,
-         _BinaryPredicate __pred) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first1, __first2);
-
-  return __pstl::__internal::__pattern_mismatch(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2, __pred);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, std::pair<_ForwardIterator1, _ForwardIterator2>>
-mismatch(_ExecutionPolicy&& __exec,
-         _ForwardIterator1 __first1,
-         _ForwardIterator1 __last1,
-         _ForwardIterator2 __first2,
-         _BinaryPredicate __pred) {
-  return std::mismatch(
-      __exec, __first1, __last1, __first2, std::next(__first2, std::distance(__first1, __last1)), __pred);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, std::pair<_ForwardIterator1, _ForwardIterator2>>
-mismatch(_ExecutionPolicy&& __exec,
-         _ForwardIterator1 __first1,
-         _ForwardIterator1 __last1,
-         _ForwardIterator2 __first2,
-         _ForwardIterator2 __last2) {
-  return std::mismatch(std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2, std::equal_to<>());
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, std::pair<_ForwardIterator1, _ForwardIterator2>>
-mismatch(_ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2) {
-  // TODO: to get rid of "distance"
-  return std::mismatch(
-      std::forward<_ExecutionPolicy>(__exec),
-      __first1,
-      __last1,
-      __first2,
-      std::next(__first2, std::distance(__first1, __last1)));
-}
-
-// [alg.equal]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-equal(_ExecutionPolicy&& __exec,
-      _ForwardIterator1 __first1,
-      _ForwardIterator1 __last1,
-      _ForwardIterator2 __first2,
-      _BinaryPredicate __p) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first1, __first2);
-
-  return __pstl::__internal::__pattern_equal(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __p);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-equal(_ExecutionPolicy&& __exec, _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2) {
-  return std::equal(std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, std::equal_to<>());
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-equal(_ExecutionPolicy&& __exec,
-      _ForwardIterator1 __first1,
-      _ForwardIterator1 __last1,
-      _ForwardIterator2 __first2,
-      _ForwardIterator2 __last2,
-      _BinaryPredicate __p) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first1, __first2);
-
-  return __pstl::__internal::__pattern_equal(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2, __p);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-equal(_ExecutionPolicy&& __exec,
-      _ForwardIterator1 __first1,
-      _ForwardIterator1 __last1,
-      _ForwardIterator2 __first2,
-      _ForwardIterator2 __last2) {
-  return equal(std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2, std::equal_to<>());
-}
-
-// [alg.move]
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2>
-move(_ExecutionPolicy&& __exec, _ForwardIterator1 __first, _ForwardIterator1 __last, _ForwardIterator2 __d_first) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __d_first);
-
-  using __is_vector = typename decltype(__dispatch_tag)::__is_vector;
-
-  return __pstl::__internal::__pattern_walk2_brick(
-      __dispatch_tag,
-      std::forward<_ExecutionPolicy>(__exec),
-      __first,
-      __last,
-      __d_first,
-      [](_ForwardIterator1 __begin, _ForwardIterator1 __end, _ForwardIterator2 __res) {
-        return __pstl::__internal::__brick_move(__begin, __end, __res, __is_vector{});
-      });
-}
-
-// [partial.sort]
-
-template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-partial_sort(_ExecutionPolicy&& __exec,
-             _RandomAccessIterator __first,
-             _RandomAccessIterator __middle,
-             _RandomAccessIterator __last,
-             _Compare __comp) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  __pstl::__internal::__pattern_partial_sort(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __middle, __last, __comp);
-}
-
-template <class _ExecutionPolicy, class _RandomAccessIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-partial_sort(_ExecutionPolicy&& __exec,
-             _RandomAccessIterator __first,
-             _RandomAccessIterator __middle,
-             _RandomAccessIterator __last) {
-  typedef typename iterator_traits<_RandomAccessIterator>::value_type _InputType;
-  std::partial_sort(__exec, __first, __middle, __last, std::less<_InputType>());
-}
-
-// [partial.sort.copy]
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _RandomAccessIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _RandomAccessIterator> partial_sort_copy(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _RandomAccessIterator __d_first,
-    _RandomAccessIterator __d_last,
-    _Compare __comp) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __d_first);
-
-  return __pstl::__internal::__pattern_partial_sort_copy(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __d_first, __d_last, __comp);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _RandomAccessIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _RandomAccessIterator> partial_sort_copy(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _RandomAccessIterator __d_first,
-    _RandomAccessIterator __d_last) {
-  return std::partial_sort_copy(
-      std::forward<_ExecutionPolicy>(__exec), __first, __last, __d_first, __d_last, std::less<>());
-}
-
-// [is.sorted]
-template <class _ExecutionPolicy, class _ForwardIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-is_sorted_until(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Compare __comp) {
-  auto __dispatch_tag          = __pstl::__internal::__select_backend(__exec, __first);
-  const _ForwardIterator __res = __pstl::__internal::__pattern_adjacent_find(
-      __dispatch_tag,
-      std::forward<_ExecutionPolicy>(__exec),
-      __first,
-      __last,
-      __pstl::__internal::__reorder_pred<_Compare>(__comp),
-      /*first_semantic*/ false);
-  return __res == __last ? __last : std::next(__res);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-is_sorted_until(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last) {
-  typedef typename std::iterator_traits<_ForwardIterator>::value_type _InputType;
-  return is_sorted_until(std::forward<_ExecutionPolicy>(__exec), __first, __last, std::less<_InputType>());
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-is_sorted(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Compare __comp) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-  return __pstl::__internal::__pattern_adjacent_find(
-             __dispatch_tag,
-             std::forward<_ExecutionPolicy>(__exec),
-             __first,
-             __last,
-             __pstl::__internal::__reorder_pred<_Compare>(__comp),
-             /*or_semantic*/ true) == __last;
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-is_sorted(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last) {
-  typedef typename std::iterator_traits<_ForwardIterator>::value_type _InputType;
-  return std::is_sorted(std::forward<_ExecutionPolicy>(__exec), __first, __last, std::less<_InputType>());
-}
-
-// [alg.merge]
-template <class _ExecutionPolicy, class _BidirectionalIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-inplace_merge(_ExecutionPolicy&& __exec,
-              _BidirectionalIterator __first,
-              _BidirectionalIterator __middle,
-              _BidirectionalIterator __last,
-              _Compare __comp) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  __pstl::__internal::__pattern_inplace_merge(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __middle, __last, __comp);
-}
-
-template <class _ExecutionPolicy, class _BidirectionalIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-inplace_merge(_ExecutionPolicy&& __exec,
-              _BidirectionalIterator __first,
-              _BidirectionalIterator __middle,
-              _BidirectionalIterator __last) {
-  typedef typename std::iterator_traits<_BidirectionalIterator>::value_type _InputType;
-  std::inplace_merge(__exec, __first, __middle, __last, std::less<_InputType>());
-}
-
-// [includes]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-includes(_ExecutionPolicy&& __exec,
-         _ForwardIterator1 __first1,
-         _ForwardIterator1 __last1,
-         _ForwardIterator2 __first2,
-         _ForwardIterator2 __last2,
-         _Compare __comp) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first1, __first2);
-
-  return __pstl::__internal::__pattern_includes(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2, __comp);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-includes(_ExecutionPolicy&& __exec,
-         _ForwardIterator1 __first1,
-         _ForwardIterator1 __last1,
-         _ForwardIterator2 __first2,
-         _ForwardIterator2 __last2) {
-  return std::includes(std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2, std::less<>());
-}
-
-// [set.union]
-
-template <class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _ForwardIterator,
-          class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-set_union(_ExecutionPolicy&& __exec,
-          _ForwardIterator1 __first1,
-          _ForwardIterator1 __last1,
-          _ForwardIterator2 __first2,
-          _ForwardIterator2 __last2,
-          _ForwardIterator __result,
-          _Compare __comp) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first1, __first2, __result);
-
-  return __pstl::__internal::__pattern_set_union(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2, __result, __comp);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-set_union(_ExecutionPolicy&& __exec,
-          _ForwardIterator1 __first1,
-          _ForwardIterator1 __last1,
-          _ForwardIterator2 __first2,
-          _ForwardIterator2 __last2,
-          _ForwardIterator __result) {
-  return std::set_union(
-      std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2, __result, std::less<>());
-}
-
-// [set.intersection]
-
-template <class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _ForwardIterator,
-          class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator> set_intersection(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _ForwardIterator __result,
-    _Compare __comp) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first1, __first2, __result);
-
-  return __pstl::__internal::__pattern_set_intersection(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2, __result, __comp);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator> set_intersection(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _ForwardIterator __result) {
-  return std::set_intersection(
-      std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2, __result, std::less<>());
-}
-
-// [set.
diff erence]
-
-template <class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _ForwardIterator,
-          class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator> set_
diff erence(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _ForwardIterator __result,
-    _Compare __comp) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first1, __first2, __result);
-
-  return __pstl::__internal::__pattern_set_
diff erence(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2, __result, __comp);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator> set_
diff erence(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _ForwardIterator __result) {
-  return std::set_
diff erence(
-      std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2, __result, std::less<>());
-}
-
-// [set.symmetric.
diff erence]
-
-template <class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _ForwardIterator,
-          class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator> set_symmetric_
diff erence(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _ForwardIterator __result,
-    _Compare __comp) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first1, __first2, __result);
-
-  return __pstl::__internal::__pattern_set_symmetric_
diff erence(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2, __result, __comp);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator> set_symmetric_
diff erence(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _ForwardIterator __result) {
-  return std::set_symmetric_
diff erence(
-      std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2, __result, std::less<>());
-}
-
-// [is.heap]
-template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _RandomAccessIterator>
-is_heap_until(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  return __pstl::__internal::__pattern_is_heap_until(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __comp);
-}
-
-template <class _ExecutionPolicy, class _RandomAccessIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _RandomAccessIterator>
-is_heap_until(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last) {
-  typedef typename std::iterator_traits<_RandomAccessIterator>::value_type _InputType;
-  return std::is_heap_until(std::forward<_ExecutionPolicy>(__exec), __first, __last, std::less<_InputType>());
-}
-
-template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-is_heap(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) {
-  return std::is_heap_until(std::forward<_ExecutionPolicy>(__exec), __first, __last, __comp) == __last;
-}
-
-template <class _ExecutionPolicy, class _RandomAccessIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool>
-is_heap(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last) {
-  typedef typename std::iterator_traits<_RandomAccessIterator>::value_type _InputType;
-  return std::is_heap(std::forward<_ExecutionPolicy>(__exec), __first, __last, std::less<_InputType>());
-}
-
-// [alg.min.max]
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-min_element(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Compare __comp) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-  return __pstl::__internal::__pattern_min_element(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __comp);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-min_element(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last) {
-  typedef typename std::iterator_traits<_ForwardIterator>::value_type _InputType;
-  return std::min_element(std::forward<_ExecutionPolicy>(__exec), __first, __last, std::less<_InputType>());
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-max_element(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Compare __comp) {
-  return min_element(
-      std::forward<_ExecutionPolicy>(__exec), __first, __last, __pstl::__internal::__reorder_pred<_Compare>(__comp));
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-max_element(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last) {
-  typedef typename std::iterator_traits<_ForwardIterator>::value_type _InputType;
-  return std::min_element(
-      std::forward<_ExecutionPolicy>(__exec),
-      __first,
-      __last,
-      __pstl::__internal::__reorder_pred<std::less<_InputType>>(std::less<_InputType>()));
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, std::pair<_ForwardIterator, _ForwardIterator>>
-minmax_element(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, _Compare __comp) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-  return __pstl::__internal::__pattern_minmax_element(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __comp);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, std::pair<_ForwardIterator, _ForwardIterator>>
-minmax_element(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last) {
-  typedef typename iterator_traits<_ForwardIterator>::value_type _ValueType;
-  return std::minmax_element(std::forward<_ExecutionPolicy>(__exec), __first, __last, std::less<_ValueType>());
-}
-
-// [alg.nth.element]
-
-template <class _ExecutionPolicy, class _RandomAccessIterator, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-nth_element(_ExecutionPolicy&& __exec,
-            _RandomAccessIterator __first,
-            _RandomAccessIterator __nth,
-            _RandomAccessIterator __last,
-            _Compare __comp) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  __pstl::__internal::__pattern_nth_element(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __nth, __last, __comp);
-}
-
-template <class _ExecutionPolicy, class _RandomAccessIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-nth_element(_ExecutionPolicy&& __exec,
-            _RandomAccessIterator __first,
-            _RandomAccessIterator __nth,
-            _RandomAccessIterator __last) {
-  typedef typename iterator_traits<_RandomAccessIterator>::value_type _InputType;
-  std::nth_element(std::forward<_ExecutionPolicy>(__exec), __first, __nth, __last, std::less<_InputType>());
-}
-
-// [alg.lex.comparison]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Compare>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool> lexicographical_compare(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2,
-    _Compare __comp) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first1, __first2);
-
-  return __pstl::__internal::__pattern_lexicographical_compare(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2, __comp);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, bool> lexicographical_compare(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first1,
-    _ForwardIterator1 __last1,
-    _ForwardIterator2 __first2,
-    _ForwardIterator2 __last2) {
-  return std::lexicographical_compare(
-      std::forward<_ExecutionPolicy>(__exec), __first1, __last1, __first2, __last2, std::less<>());
-}
-
-} // namespace std
-
-#endif /* _PSTL_GLUE_ALGORITHM_IMPL_H */

diff  --git a/libcxx/include/__pstl/internal/glue_memory_defs.h b/libcxx/include/__pstl/internal/glue_memory_defs.h
deleted file mode 100644
index 4e8581cfdb80c6..00000000000000
--- a/libcxx/include/__pstl/internal/glue_memory_defs.h
+++ /dev/null
@@ -1,81 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_GLUE_MEMORY_DEFS_H
-#define _PSTL_GLUE_MEMORY_DEFS_H
-
-#include <__config>
-
-#include "execution_defs.h"
-
-namespace std {
-
-// [uninitialized.copy]
-
-template <class _ExecutionPolicy, class _InputIterator, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-uninitialized_copy(_ExecutionPolicy&& __exec, _InputIterator __first, _InputIterator __last, _ForwardIterator __result);
-
-template <class _ExecutionPolicy, class _InputIterator, class _Size, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-uninitialized_copy_n(_ExecutionPolicy&& __exec, _InputIterator __first, _Size __n, _ForwardIterator __result);
-
-// [uninitialized.move]
-
-template <class _ExecutionPolicy, class _InputIterator, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-uninitialized_move(_ExecutionPolicy&& __exec, _InputIterator __first, _InputIterator __last, _ForwardIterator __result);
-
-template <class _ExecutionPolicy, class _InputIterator, class _Size, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-uninitialized_move_n(_ExecutionPolicy&& __exec, _InputIterator __first, _Size __n, _ForwardIterator __result);
-
-// [uninitialized.fill]
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Tp>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-uninitialized_fill(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value);
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Size, class _Tp>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-uninitialized_fill_n(_ExecutionPolicy&& __exec, _ForwardIterator __first, _Size __n, const _Tp& __value);
-
-// [specialized.destroy]
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-destroy(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last);
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Size>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-destroy_n(_ExecutionPolicy&& __exec, _ForwardIterator __first, _Size __n);
-
-// [uninitialized.construct.default]
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-uninitialized_default_construct(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last);
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Size>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-uninitialized_default_construct_n(_ExecutionPolicy&& __exec, _ForwardIterator __first, _Size __n);
-
-// [uninitialized.construct.value]
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-uninitialized_value_construct(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last);
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Size>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-uninitialized_value_construct_n(_ExecutionPolicy&& __exec, _ForwardIterator __first, _Size __n);
-
-} //  namespace std
-
-#endif /* _PSTL_GLUE_MEMORY_DEFS_H */

diff  --git a/libcxx/include/__pstl/internal/glue_memory_impl.h b/libcxx/include/__pstl/internal/glue_memory_impl.h
deleted file mode 100644
index b645ba3fca1093..00000000000000
--- a/libcxx/include/__pstl/internal/glue_memory_impl.h
+++ /dev/null
@@ -1,379 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_GLUE_MEMORY_IMPL_H
-#define _PSTL_GLUE_MEMORY_IMPL_H
-
-#include <__config>
-
-#include "algorithm_fwd.h"
-#include "execution_defs.h"
-#include "utils.h"
-
-#include "execution_impl.h"
-
-namespace std {
-
-// [uninitialized.copy]
-
-template <class _ExecutionPolicy, class _InputIterator, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator> uninitialized_copy(
-    _ExecutionPolicy&& __exec, _InputIterator __first, _InputIterator __last, _ForwardIterator __result) {
-  typedef typename iterator_traits<_InputIterator>::value_type _ValueType1;
-  typedef typename iterator_traits<_ForwardIterator>::value_type _ValueType2;
-  typedef typename iterator_traits<_InputIterator>::reference _ReferenceType1;
-  typedef typename iterator_traits<_ForwardIterator>::reference _ReferenceType2;
-
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __result);
-
-  using __is_vector = typename decltype(__dispatch_tag)::__is_vector;
-
-  return __pstl::__internal::__invoke_if_else(
-      std::integral_constant < bool,
-      std::is_trivial<_ValueType1>::value&& std::is_trivial<_ValueType2>::value > (),
-      [&]() {
-        return __pstl::__internal::__pattern_walk2_brick(
-            __dispatch_tag,
-            std::forward<_ExecutionPolicy>(__exec),
-            __first,
-            __last,
-            __result,
-            [](_InputIterator __begin, _InputIterator __end, _ForwardIterator __res) {
-              return __pstl::__internal::__brick_copy(__begin, __end, __res, __is_vector{});
-            });
-      },
-      [&]() {
-        return __pstl::__internal::__pattern_walk2(
-            __dispatch_tag,
-            std::forward<_ExecutionPolicy>(__exec),
-            __first,
-            __last,
-            __result,
-            [](_ReferenceType1 __val1, _ReferenceType2 __val2) { ::new (std::addressof(__val2)) _ValueType2(__val1); });
-      });
-}
-
-template <class _ExecutionPolicy, class _InputIterator, class _Size, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-uninitialized_copy_n(_ExecutionPolicy&& __exec, _InputIterator __first, _Size __n, _ForwardIterator __result) {
-  typedef typename iterator_traits<_InputIterator>::value_type _ValueType1;
-  typedef typename iterator_traits<_ForwardIterator>::value_type _ValueType2;
-  typedef typename iterator_traits<_InputIterator>::reference _ReferenceType1;
-  typedef typename iterator_traits<_ForwardIterator>::reference _ReferenceType2;
-
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __result);
-
-  using __is_vector = typename decltype(__dispatch_tag)::__is_vector;
-
-  return __pstl::__internal::__invoke_if_else(
-      std::integral_constant < bool,
-      std::is_trivial<_ValueType1>::value&& std::is_trivial<_ValueType2>::value > (),
-      [&]() {
-        return __pstl::__internal::__pattern_walk2_brick_n(
-            __dispatch_tag,
-            std::forward<_ExecutionPolicy>(__exec),
-            __first,
-            __n,
-            __result,
-            [](_InputIterator __begin, _Size __sz, _ForwardIterator __res) {
-              return __pstl::__internal::__brick_copy_n(__begin, __sz, __res, __is_vector{});
-            });
-      },
-      [&]() {
-        return __pstl::__internal::__pattern_walk2_n(
-            __dispatch_tag,
-            std::forward<_ExecutionPolicy>(__exec),
-            __first,
-            __n,
-            __result,
-            [](_ReferenceType1 __val1, _ReferenceType2 __val2) { ::new (std::addressof(__val2)) _ValueType2(__val1); });
-      });
-}
-
-// [uninitialized.move]
-
-template <class _ExecutionPolicy, class _InputIterator, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator> uninitialized_move(
-    _ExecutionPolicy&& __exec, _InputIterator __first, _InputIterator __last, _ForwardIterator __result) {
-  typedef typename iterator_traits<_InputIterator>::value_type _ValueType1;
-  typedef typename iterator_traits<_ForwardIterator>::value_type _ValueType2;
-  typedef typename iterator_traits<_InputIterator>::reference _ReferenceType1;
-  typedef typename iterator_traits<_ForwardIterator>::reference _ReferenceType2;
-
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __result);
-
-  using __is_vector = typename decltype(__dispatch_tag)::__is_vector;
-
-  return __pstl::__internal::__invoke_if_else(
-      std::integral_constant < bool,
-      std::is_trivial<_ValueType1>::value&& std::is_trivial<_ValueType2>::value > (),
-      [&]() {
-        return __pstl::__internal::__pattern_walk2_brick(
-            __dispatch_tag,
-            std::forward<_ExecutionPolicy>(__exec),
-            __first,
-            __last,
-            __result,
-            [](_InputIterator __begin, _InputIterator __end, _ForwardIterator __res) {
-              return __pstl::__internal::__brick_copy(__begin, __end, __res, __is_vector{});
-            });
-      },
-      [&]() {
-        return __pstl::__internal::__pattern_walk2(
-            __dispatch_tag,
-            std::forward<_ExecutionPolicy>(__exec),
-            __first,
-            __last,
-            __result,
-            [](_ReferenceType1 __val1, _ReferenceType2 __val2) {
-              ::new (std::addressof(__val2)) _ValueType2(std::move(__val1));
-            });
-      });
-}
-
-template <class _ExecutionPolicy, class _InputIterator, class _Size, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-uninitialized_move_n(_ExecutionPolicy&& __exec, _InputIterator __first, _Size __n, _ForwardIterator __result) {
-  typedef typename iterator_traits<_InputIterator>::value_type _ValueType1;
-  typedef typename iterator_traits<_ForwardIterator>::value_type _ValueType2;
-  typedef typename iterator_traits<_InputIterator>::reference _ReferenceType1;
-  typedef typename iterator_traits<_ForwardIterator>::reference _ReferenceType2;
-
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __result);
-
-  using __is_vector = typename decltype(__dispatch_tag)::__is_vector;
-
-  return __pstl::__internal::__invoke_if_else(
-      std::integral_constant < bool,
-      std::is_trivial<_ValueType1>::value&& std::is_trivial<_ValueType2>::value > (),
-      [&]() {
-        return __pstl::__internal::__pattern_walk2_brick_n(
-            __dispatch_tag,
-            std::forward<_ExecutionPolicy>(__exec),
-            __first,
-            __n,
-            __result,
-            [](_InputIterator __begin, _Size __sz, _ForwardIterator __res) {
-              return __pstl::__internal::__brick_copy_n(__begin, __sz, __res, __is_vector{});
-            });
-      },
-      [&]() {
-        return __pstl::__internal::__pattern_walk2_n(
-            __dispatch_tag,
-            std::forward<_ExecutionPolicy>(__exec),
-            __first,
-            __n,
-            __result,
-            [](_ReferenceType1 __val1, _ReferenceType2 __val2) {
-              ::new (std::addressof(__val2)) _ValueType2(std::move(__val1));
-            });
-      });
-}
-
-// [uninitialized.fill]
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Tp>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-uninitialized_fill(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value) {
-  typedef typename iterator_traits<_ForwardIterator>::value_type _ValueType;
-  typedef typename iterator_traits<_ForwardIterator>::reference _ReferenceType;
-
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  using __is_vector = typename decltype(__dispatch_tag)::__is_vector;
-
-  __pstl::__internal::__invoke_if_else(
-      std::is_arithmetic<_ValueType>(),
-      [&]() {
-        __pstl::__internal::__pattern_walk_brick(
-            __dispatch_tag,
-            std::forward<_ExecutionPolicy>(__exec),
-            __first,
-            __last,
-            [&__value](_ForwardIterator __begin, _ForwardIterator __end) {
-              __pstl::__internal::__brick_fill(__begin, __end, _ValueType(__value), __is_vector{});
-            });
-      },
-      [&]() {
-        __pstl::__internal::__pattern_walk1(
-            __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, [&__value](_ReferenceType __val) {
-              ::new (std::addressof(__val)) _ValueType(__value);
-            });
-      });
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Size, class _Tp>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-uninitialized_fill_n(_ExecutionPolicy&& __exec, _ForwardIterator __first, _Size __n, const _Tp& __value) {
-  typedef typename iterator_traits<_ForwardIterator>::value_type _ValueType;
-  typedef typename iterator_traits<_ForwardIterator>::reference _ReferenceType;
-
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  using __is_vector = typename decltype(__dispatch_tag)::__is_vector;
-
-  return __pstl::__internal::__invoke_if_else(
-      std::is_arithmetic<_ValueType>(),
-      [&]() {
-        return __pstl::__internal::__pattern_walk_brick_n(
-            __dispatch_tag,
-            std::forward<_ExecutionPolicy>(__exec),
-            __first,
-            __n,
-            [&__value](_ForwardIterator __begin, _Size __count) {
-              return __pstl::__internal::__brick_fill_n(__begin, __count, _ValueType(__value), __is_vector{});
-            });
-      },
-      [&]() {
-        return __pstl::__internal::__pattern_walk1_n(
-            __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __n, [&__value](_ReferenceType __val) {
-              ::new (std::addressof(__val)) _ValueType(__value);
-            });
-      });
-}
-
-// [specialized.destroy]
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-destroy(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last) {
-  typedef typename iterator_traits<_ForwardIterator>::value_type _ValueType;
-  typedef typename iterator_traits<_ForwardIterator>::reference _ReferenceType;
-
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  __pstl::__internal::__invoke_if_not(std::is_trivially_destructible<_ValueType>(), [&]() {
-    __pstl::__internal::__pattern_walk1(
-        __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, [](_ReferenceType __val) {
-          __val.~_ValueType();
-        });
-  });
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Size>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-destroy_n(_ExecutionPolicy&& __exec, _ForwardIterator __first, _Size __n) {
-  typedef typename iterator_traits<_ForwardIterator>::value_type _ValueType;
-  typedef typename iterator_traits<_ForwardIterator>::reference _ReferenceType;
-
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  return __pstl::__internal::__invoke_if_else(
-      std::is_trivially_destructible<_ValueType>(),
-      [&]() { return std::next(__first, __n); },
-      [&]() {
-        return __pstl::__internal::__pattern_walk1_n(
-            __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __n, [](_ReferenceType __val) {
-              __val.~_ValueType();
-            });
-      });
-}
-
-// [uninitialized.construct.default]
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-uninitialized_default_construct(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last) {
-  typedef typename iterator_traits<_ForwardIterator>::value_type _ValueType;
-  typedef typename iterator_traits<_ForwardIterator>::reference _ReferenceType;
-
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  __pstl::__internal::__invoke_if_not(std::is_trivial<_ValueType>(), [&]() {
-    __pstl::__internal::__pattern_walk1(
-        __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, [](_ReferenceType __val) {
-          ::new (std::addressof(__val)) _ValueType;
-        });
-  });
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Size>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-uninitialized_default_construct_n(_ExecutionPolicy&& __exec, _ForwardIterator __first, _Size __n) {
-  typedef typename iterator_traits<_ForwardIterator>::value_type _ValueType;
-  typedef typename iterator_traits<_ForwardIterator>::reference _ReferenceType;
-
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  return __pstl::__internal::__invoke_if_else(
-      std::is_trivial<_ValueType>(),
-      [&]() { return std::next(__first, __n); },
-      [&]() {
-        return __pstl::__internal::__pattern_walk1_n(
-            __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __n, [](_ReferenceType __val) {
-              ::new (std::addressof(__val)) _ValueType;
-            });
-      });
-}
-
-// [uninitialized.construct.value]
-
-template <class _ExecutionPolicy, class _ForwardIterator>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void>
-uninitialized_value_construct(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last) {
-  typedef typename iterator_traits<_ForwardIterator>::value_type _ValueType;
-  typedef typename iterator_traits<_ForwardIterator>::reference _ReferenceType;
-
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  using __is_vector = typename decltype(__dispatch_tag)::__is_vector;
-
-  __pstl::__internal::__invoke_if_else(
-      std::is_trivial<_ValueType>(),
-      [&]() {
-        __pstl::__internal::__pattern_walk_brick(
-            __dispatch_tag,
-            std::forward<_ExecutionPolicy>(__exec),
-            __first,
-            __last,
-            [](_ForwardIterator __begin, _ForwardIterator __end) {
-              __pstl::__internal::__brick_fill(__begin, __end, _ValueType(), __is_vector{});
-            });
-      },
-      [&]() {
-        __pstl::__internal::__pattern_walk1(
-            __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, [](_ReferenceType __val) {
-              ::new (std::addressof(__val)) _ValueType();
-            });
-      });
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Size>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator>
-uninitialized_value_construct_n(_ExecutionPolicy&& __exec, _ForwardIterator __first, _Size __n) {
-  typedef typename iterator_traits<_ForwardIterator>::value_type _ValueType;
-  typedef typename iterator_traits<_ForwardIterator>::reference _ReferenceType;
-
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first);
-
-  using __is_vector = typename decltype(__dispatch_tag)::__is_vector;
-
-  return __pstl::__internal::__invoke_if_else(
-      std::is_trivial<_ValueType>(),
-      [&]() {
-        return __pstl::__internal::__pattern_walk_brick_n(
-            __dispatch_tag,
-            std::forward<_ExecutionPolicy>(__exec),
-            __first,
-            __n,
-            [](_ForwardIterator __begin, _Size __count) {
-              return __pstl::__internal::__brick_fill_n(__begin, __count, _ValueType(), __is_vector{});
-            });
-      },
-      [&]() {
-        return __pstl::__internal::__pattern_walk1_n(
-            __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __n, [](_ReferenceType __val) {
-              ::new (std::addressof(__val)) _ValueType();
-            });
-      });
-}
-
-} // namespace std
-
-#endif /* _PSTL_GLUE_MEMORY_IMPL_H */

diff  --git a/libcxx/include/__pstl/internal/glue_numeric_defs.h b/libcxx/include/__pstl/internal/glue_numeric_defs.h
deleted file mode 100644
index 05c71665eb58dd..00000000000000
--- a/libcxx/include/__pstl/internal/glue_numeric_defs.h
+++ /dev/null
@@ -1,124 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_GLUE_NUMERIC_DEFS_H
-#define _PSTL_GLUE_NUMERIC_DEFS_H
-
-#include <__config>
-#include <iterator>
-
-#include "execution_defs.h"
-
-namespace std {
-// [exclusive.scan]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Tp>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> exclusive_scan(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __result,
-    _Tp __init);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Tp, class _BinaryOperation>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> exclusive_scan(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __result,
-    _Tp __init,
-    _BinaryOperation __binary_op);
-
-// [inclusive.scan]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> inclusive_scan(
-    _ExecutionPolicy&& __exec, _ForwardIterator1 __first, _ForwardIterator1 __last, _ForwardIterator2 __result);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryOperation>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> inclusive_scan(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __result,
-    _BinaryOperation __binary_op);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Tp, class _BinaryOperation>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> inclusive_scan(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __result,
-    _BinaryOperation __binary_op,
-    _Tp __init);
-
-// [transform.exclusive.scan]
-
-template <class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _Tp,
-          class _BinaryOperation,
-          class _UnaryOperation>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> transform_exclusive_scan(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __result,
-    _Tp __init,
-    _BinaryOperation __binary_op,
-    _UnaryOperation __unary_op);
-
-// [transform.inclusive.scan]
-
-template <class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _BinaryOperation,
-          class _UnaryOperation,
-          class _Tp>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> transform_inclusive_scan(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __result,
-    _BinaryOperation __binary_op,
-    _UnaryOperation __unary_op,
-    _Tp __init);
-
-template <class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _UnaryOperation,
-          class _BinaryOperation>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> transform_inclusive_scan(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __result,
-    _BinaryOperation __binary_op,
-    _UnaryOperation __unary_op);
-
-// [adjacent.
diff erence]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryOperation>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> adjacent_
diff erence(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __d_first,
-    _BinaryOperation op);
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> adjacent_
diff erence(
-    _ExecutionPolicy&& __exec, _ForwardIterator1 __first, _ForwardIterator1 __last, _ForwardIterator2 __d_first);
-
-} // namespace std
-
-#endif /* _PSTL_GLUE_NUMERIC_DEFS_H */

diff  --git a/libcxx/include/__pstl/internal/glue_numeric_impl.h b/libcxx/include/__pstl/internal/glue_numeric_impl.h
deleted file mode 100644
index 4e6516a06cf2c5..00000000000000
--- a/libcxx/include/__pstl/internal/glue_numeric_impl.h
+++ /dev/null
@@ -1,223 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_GLUE_NUMERIC_IMPL_H
-#define _PSTL_GLUE_NUMERIC_IMPL_H
-
-#include <__config>
-#include <functional>
-
-#include "execution_impl.h"
-#include "numeric_fwd.h"
-#include "utils.h"
-
-namespace std {
-
-// [exclusive.scan]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Tp>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> exclusive_scan(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __result,
-    _Tp __init) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __result);
-
-  using namespace __pstl;
-  return __internal::__pattern_transform_scan(
-      __dispatch_tag,
-      std::forward<_ExecutionPolicy>(__exec),
-      __first,
-      __last,
-      __result,
-      __pstl::__internal::__no_op(),
-      __init,
-      std::plus<_Tp>(),
-      /*inclusive=*/std::false_type());
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Tp, class _BinaryOperation>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> exclusive_scan(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __result,
-    _Tp __init,
-    _BinaryOperation __binary_op) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __result);
-
-  using namespace __pstl;
-  return __internal::__pattern_transform_scan(
-      __dispatch_tag,
-      std::forward<_ExecutionPolicy>(__exec),
-      __first,
-      __last,
-      __result,
-      __pstl::__internal::__no_op(),
-      __init,
-      __binary_op,
-      /*inclusive=*/std::false_type());
-}
-
-// [inclusive.scan]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> inclusive_scan(
-    _ExecutionPolicy&& __exec, _ForwardIterator1 __first, _ForwardIterator1 __last, _ForwardIterator2 __result) {
-  typedef typename iterator_traits<_ForwardIterator1>::value_type _InputType;
-  return transform_inclusive_scan(
-      std::forward<_ExecutionPolicy>(__exec),
-      __first,
-      __last,
-      __result,
-      std::plus<_InputType>(),
-      __pstl::__internal::__no_op());
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryOperation>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> inclusive_scan(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __result,
-    _BinaryOperation __binary_op) {
-  return transform_inclusive_scan(
-      std::forward<_ExecutionPolicy>(__exec), __first, __last, __result, __binary_op, __pstl::__internal::__no_op());
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Tp, class _BinaryOperation>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> inclusive_scan(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __result,
-    _BinaryOperation __binary_op,
-    _Tp __init) {
-  return transform_inclusive_scan(
-      std::forward<_ExecutionPolicy>(__exec),
-      __first,
-      __last,
-      __result,
-      __binary_op,
-      __pstl::__internal::__no_op(),
-      __init);
-}
-
-// [transform.exclusive.scan]
-
-template <class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _Tp,
-          class _BinaryOperation,
-          class _UnaryOperation>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> transform_exclusive_scan(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __result,
-    _Tp __init,
-    _BinaryOperation __binary_op,
-    _UnaryOperation __unary_op) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __result);
-
-  return __pstl::__internal::__pattern_transform_scan(
-      __dispatch_tag,
-      std::forward<_ExecutionPolicy>(__exec),
-      __first,
-      __last,
-      __result,
-      __unary_op,
-      __init,
-      __binary_op,
-      /*inclusive=*/std::false_type());
-}
-
-// [transform.inclusive.scan]
-
-template <class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _BinaryOperation,
-          class _UnaryOperation,
-          class _Tp>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> transform_inclusive_scan(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __result,
-    _BinaryOperation __binary_op,
-    _UnaryOperation __unary_op,
-    _Tp __init) {
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __result);
-
-  return __pstl::__internal::__pattern_transform_scan(
-      __dispatch_tag,
-      std::forward<_ExecutionPolicy>(__exec),
-      __first,
-      __last,
-      __result,
-      __unary_op,
-      __init,
-      __binary_op,
-      /*inclusive=*/std::true_type());
-}
-
-template <class _ExecutionPolicy,
-          class _ForwardIterator1,
-          class _ForwardIterator2,
-          class _UnaryOperation,
-          class _BinaryOperation>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> transform_inclusive_scan(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __result,
-    _BinaryOperation __binary_op,
-    _UnaryOperation __unary_op) {
-  if (__first != __last) {
-    auto __tmp = __unary_op(*__first);
-    *__result  = __tmp;
-    return transform_inclusive_scan(
-        std::forward<_ExecutionPolicy>(__exec), ++__first, __last, ++__result, __binary_op, __unary_op, __tmp);
-  } else {
-    return __result;
-  }
-}
-
-// [adjacent.
diff erence]
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryOperation>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> adjacent_
diff erence(
-    _ExecutionPolicy&& __exec,
-    _ForwardIterator1 __first,
-    _ForwardIterator1 __last,
-    _ForwardIterator2 __d_first,
-    _BinaryOperation __op) {
-  if (__first == __last)
-    return __d_first;
-
-  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __d_first);
-
-  return __pstl::__internal::__pattern_adjacent_
diff erence(
-      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __d_first, __op);
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
-__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> adjacent_
diff erence(
-    _ExecutionPolicy&& __exec, _ForwardIterator1 __first, _ForwardIterator1 __last, _ForwardIterator2 __d_first) {
-  typedef typename iterator_traits<_ForwardIterator1>::value_type _ValueType;
-  return adjacent_
diff erence(
-      std::forward<_ExecutionPolicy>(__exec), __first, __last, __d_first, std::minus<_ValueType>());
-}
-
-} // namespace std
-
-#endif /* _PSTL_GLUE_NUMERIC_IMPL_H_ */

diff  --git a/libcxx/include/__pstl/internal/memory_impl.h b/libcxx/include/__pstl/internal/memory_impl.h
deleted file mode 100644
index 5315ccd9a344a8..00000000000000
--- a/libcxx/include/__pstl/internal/memory_impl.h
+++ /dev/null
@@ -1,106 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_MEMORY_IMPL_H
-#define _PSTL_MEMORY_IMPL_H
-
-#include <__config>
-#include <iterator>
-
-#include "unseq_backend_simd.h"
-
-namespace __pstl {
-namespace __internal {
-
-//------------------------------------------------------------------------
-// uninitialized_move
-//------------------------------------------------------------------------
-
-template <typename _ForwardIterator, typename _OutputIterator>
-_OutputIterator __brick_uninitialized_move(
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _OutputIterator __result,
-    /*vector=*/std::false_type) noexcept {
-  using _ValueType = typename std::iterator_traits<_OutputIterator>::value_type;
-  for (; __first != __last; ++__first, ++__result) {
-    ::new (std::addressof(*__result)) _ValueType(std::move(*__first));
-  }
-  return __result;
-}
-
-template <typename _RandomAccessIterator, typename _OutputIterator>
-_OutputIterator __brick_uninitialized_move(
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _OutputIterator __result,
-    /*vector=*/std::true_type) noexcept {
-  using __ValueType     = typename std::iterator_traits<_OutputIterator>::value_type;
-  using _ReferenceType1 = typename std::iterator_traits<_RandomAccessIterator>::reference;
-  using _ReferenceType2 = typename std::iterator_traits<_OutputIterator>::reference;
-
-  return __unseq_backend::__simd_walk_2(
-      __first, __last - __first, __result, [](_ReferenceType1 __x, _ReferenceType2 __y) {
-        ::new (std::addressof(__y)) __ValueType(std::move(__x));
-      });
-}
-
-template <typename _Iterator>
-void __brick_destroy(_Iterator __first, _Iterator __last, /*vector*/ std::false_type) noexcept {
-  using _ValueType = typename std::iterator_traits<_Iterator>::value_type;
-
-  for (; __first != __last; ++__first)
-    __first->~_ValueType();
-}
-
-template <typename _RandomAccessIterator>
-void __brick_destroy(_RandomAccessIterator __first, _RandomAccessIterator __last, /*vector*/ std::true_type) noexcept {
-  using _ValueType     = typename std::iterator_traits<_RandomAccessIterator>::value_type;
-  using _ReferenceType = typename std::iterator_traits<_RandomAccessIterator>::reference;
-
-  __unseq_backend::__simd_walk_1(__first, __last - __first, [](_ReferenceType __x) { __x.~_ValueType(); });
-}
-
-//------------------------------------------------------------------------
-// uninitialized copy
-//------------------------------------------------------------------------
-
-template <typename _ForwardIterator, typename _OutputIterator>
-_OutputIterator __brick_uninitialized_copy(
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _OutputIterator __result,
-    /*vector=*/std::false_type) noexcept {
-  using _ValueType = typename std::iterator_traits<_OutputIterator>::value_type;
-  for (; __first != __last; ++__first, ++__result) {
-    ::new (std::addressof(*__result)) _ValueType(*__first);
-  }
-  return __result;
-}
-
-template <typename _RandomAccessIterator, typename _OutputIterator>
-_OutputIterator __brick_uninitialized_copy(
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _OutputIterator __result,
-    /*vector=*/std::true_type) noexcept {
-  using __ValueType     = typename std::iterator_traits<_OutputIterator>::value_type;
-  using _ReferenceType1 = typename std::iterator_traits<_RandomAccessIterator>::reference;
-  using _ReferenceType2 = typename std::iterator_traits<_OutputIterator>::reference;
-
-  return __unseq_backend::__simd_walk_2(
-      __first, __last - __first, __result, [](_ReferenceType1 __x, _ReferenceType2 __y) {
-        ::new (std::addressof(__y)) __ValueType(__x);
-      });
-}
-
-} // namespace __internal
-} // namespace __pstl
-
-#endif /* _PSTL_MEMORY_IMPL_H */

diff  --git a/libcxx/include/__pstl/internal/numeric_fwd.h b/libcxx/include/__pstl/internal/numeric_fwd.h
deleted file mode 100644
index 09f9b11d62da37..00000000000000
--- a/libcxx/include/__pstl/internal/numeric_fwd.h
+++ /dev/null
@@ -1,143 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_NUMERIC_FWD_H
-#define _PSTL_NUMERIC_FWD_H
-
-#include <__config>
-#include <type_traits>
-#include <utility>
-
-namespace __pstl {
-namespace __internal {
-
-//------------------------------------------------------------------------
-// transform_exclusive_scan
-//
-// walk3 evaluates f(x,y,z) for (x,y,z) drawn from [first1,last1), [first2,...), [first3,...)
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _OutputIterator, class _UnaryOperation, class _Tp, class _BinaryOperation>
-std::pair<_OutputIterator, _Tp> __brick_transform_scan(
-    _ForwardIterator,
-    _ForwardIterator,
-    _OutputIterator,
-    _UnaryOperation,
-    _Tp,
-    _BinaryOperation,
-    /*Inclusive*/ std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _OutputIterator, class _UnaryOperation, class _Tp, class _BinaryOperation>
-std::pair<_OutputIterator, _Tp> __brick_transform_scan(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _OutputIterator,
-    _UnaryOperation,
-    _Tp,
-    _BinaryOperation,
-    /*Inclusive*/ std::true_type) noexcept;
-
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _ForwardIterator,
-          class _OutputIterator,
-          class _UnaryOperation,
-          class _Tp,
-          class _BinaryOperation,
-          class _Inclusive>
-_OutputIterator __pattern_transform_scan(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator,
-    _ForwardIterator,
-    _OutputIterator,
-    _UnaryOperation,
-    _Tp,
-    _BinaryOperation,
-    _Inclusive) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator,
-          class _OutputIterator,
-          class _UnaryOperation,
-          class _Tp,
-          class _BinaryOperation,
-          class _Inclusive>
-typename std::enable_if<!std::is_floating_point<_Tp>::value, _OutputIterator>::type __pattern_transform_scan(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _OutputIterator,
-    _UnaryOperation,
-    _Tp,
-    _BinaryOperation,
-    _Inclusive);
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator,
-          class _OutputIterator,
-          class _UnaryOperation,
-          class _Tp,
-          class _BinaryOperation,
-          class _Inclusive>
-typename std::enable_if<std::is_floating_point<_Tp>::value, _OutputIterator>::type __pattern_transform_scan(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _OutputIterator,
-    _UnaryOperation,
-    _Tp,
-    _BinaryOperation,
-    _Inclusive);
-
-//------------------------------------------------------------------------
-// adjacent_
diff erence
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _OutputIterator, class _BinaryOperation>
-_OutputIterator __brick_adjacent_
diff erence(
-    _ForwardIterator,
-    _ForwardIterator,
-    _OutputIterator,
-    _BinaryOperation,
-    /*is_vector*/ std::false_type) noexcept;
-
-template <class _RandomAccessIterator, class _OutputIterator, class _BinaryOperation>
-_OutputIterator __brick_adjacent_
diff erence(
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _OutputIterator,
-    _BinaryOperation,
-    /*is_vector*/ std::true_type) noexcept;
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _OutputIterator, class _BinaryOperation>
-_OutputIterator __pattern_adjacent_
diff erence(
-    _Tag, _ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, _OutputIterator, _BinaryOperation) noexcept;
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator,
-          class _OutputIterator,
-          class _BinaryOperation>
-_OutputIterator __pattern_adjacent_
diff erence(
-    __parallel_tag<_IsVector>,
-    _ExecutionPolicy&&,
-    _RandomAccessIterator,
-    _RandomAccessIterator,
-    _OutputIterator,
-    _BinaryOperation);
-
-} // namespace __internal
-} // namespace __pstl
-
-#endif /* _PSTL_NUMERIC_FWD_H */

diff  --git a/libcxx/include/__pstl/internal/numeric_impl.h b/libcxx/include/__pstl/internal/numeric_impl.h
deleted file mode 100644
index 484f26ade22c72..00000000000000
--- a/libcxx/include/__pstl/internal/numeric_impl.h
+++ /dev/null
@@ -1,364 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_NUMERIC_IMPL_H
-#define _PSTL_NUMERIC_IMPL_H
-
-#include <__assert>
-#include <__config>
-#include <iterator>
-#include <type_traits>
-#include <numeric>
-
-#include "parallel_backend.h"
-#include "execution_impl.h"
-#include "unseq_backend_simd.h"
-#include "algorithm_fwd.h"
-
-namespace __pstl {
-namespace __internal {
-
-//------------------------------------------------------------------------
-// transform_exclusive_scan
-//
-// walk3 evaluates f(x,y,z) for (x,y,z) drawn from [first1,last1), [first2,...), [first3,...)
-//------------------------------------------------------------------------
-
-// Exclusive form
-template <class _ForwardIterator, class _OutputIterator, class _UnaryOperation, class _Tp, class _BinaryOperation>
-std::pair<_OutputIterator, _Tp> __brick_transform_scan(
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _OutputIterator __result,
-    _UnaryOperation __unary_op,
-    _Tp __init,
-    _BinaryOperation __binary_op,
-    /*Inclusive*/ std::false_type,
-    /*is_vector=*/std::false_type) noexcept {
-  for (; __first != __last; ++__first, ++__result) {
-    *__result = __init;
-    __init = __binary_op(__init, __unary_op(*__first));
-  }
-  return std::make_pair(__result, __init);
-}
-
-// Inclusive form
-template <class _RandomAccessIterator, class _OutputIterator, class _UnaryOperation, class _Tp, class _BinaryOperation>
-std::pair<_OutputIterator, _Tp> __brick_transform_scan(
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _OutputIterator __result,
-    _UnaryOperation __unary_op,
-    _Tp __init,
-    _BinaryOperation __binary_op,
-    /*Inclusive*/ std::true_type,
-    /*is_vector=*/std::false_type) noexcept {
-  for (; __first != __last; ++__first, ++__result) {
-    __init    = __binary_op(__init, __unary_op(*__first));
-    *__result = __init;
-  }
-  return std::make_pair(__result, __init);
-}
-
-// type is arithmetic and binary operation is a user defined operation.
-template <typename _Tp, typename _BinaryOperation>
-using is_arithmetic_udop =
-    std::integral_constant<bool,
-                           std::is_arithmetic<_Tp>::value && !std::is_same<_BinaryOperation, std::plus<_Tp>>::value>;
-
-// [restriction] - T shall be DefaultConstructible.
-// [violation] - default ctor of T shall set the identity value for binary_op.
-template <class _RandomAccessIterator,
-          class _OutputIterator,
-          class _UnaryOperation,
-          class _Tp,
-          class _BinaryOperation,
-          class _Inclusive>
-typename std::enable_if<!is_arithmetic_udop<_Tp, _BinaryOperation>::value, std::pair<_OutputIterator, _Tp>>::type
-__brick_transform_scan(
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _OutputIterator __result,
-    _UnaryOperation __unary_op,
-    _Tp __init,
-    _BinaryOperation __binary_op,
-    _Inclusive,
-    /*is_vector=*/std::true_type) noexcept {
-#if defined(_PSTL_UDS_PRESENT)
-  return __unseq_backend::__simd_scan(
-      __first, __last - __first, __result, __unary_op, __init, __binary_op, _Inclusive());
-#else
-  // We need to call serial brick here to call function for inclusive and exclusive scan that depends on _Inclusive()
-  // value
-  return __internal::__brick_transform_scan(
-      __first,
-      __last,
-      __result,
-      __unary_op,
-      __init,
-      __binary_op,
-      _Inclusive(),
-      /*is_vector=*/std::false_type());
-#endif
-}
-
-template <class _RandomAccessIterator,
-          class _OutputIterator,
-          class _UnaryOperation,
-          class _Tp,
-          class _BinaryOperation,
-          class _Inclusive>
-typename std::enable_if<is_arithmetic_udop<_Tp, _BinaryOperation>::value, std::pair<_OutputIterator, _Tp>>::type
-__brick_transform_scan(
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _OutputIterator __result,
-    _UnaryOperation __unary_op,
-    _Tp __init,
-    _BinaryOperation __binary_op,
-    _Inclusive,
-    /*is_vector=*/std::true_type) noexcept {
-  return __internal::__brick_transform_scan(
-      __first,
-      __last,
-      __result,
-      __unary_op,
-      __init,
-      __binary_op,
-      _Inclusive(),
-      /*is_vector=*/std::false_type());
-}
-
-template <class _Tag,
-          class _ExecutionPolicy,
-          class _ForwardIterator,
-          class _OutputIterator,
-          class _UnaryOperation,
-          class _Tp,
-          class _BinaryOperation,
-          class _Inclusive>
-_OutputIterator __pattern_transform_scan(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _OutputIterator __result,
-    _UnaryOperation __unary_op,
-    _Tp __init,
-    _BinaryOperation __binary_op,
-    _Inclusive) noexcept {
-  return __internal::__brick_transform_scan(
-             __first, __last, __result, __unary_op, __init, __binary_op, _Inclusive(), typename _Tag::__is_vector{})
-      .first;
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator,
-          class _OutputIterator,
-          class _UnaryOperation,
-          class _Tp,
-          class _BinaryOperation,
-          class _Inclusive>
-typename std::enable_if<!std::is_floating_point<_Tp>::value, _OutputIterator>::type __pattern_transform_scan(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _OutputIterator __result,
-    _UnaryOperation __unary_op,
-    _Tp __init,
-    _BinaryOperation __binary_op,
-    _Inclusive) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  typedef typename std::iterator_traits<_RandomAccessIterator>::
diff erence_type _DifferenceType;
-
-  return __internal::__except_handler([&]() {
-    __par_backend::__parallel_transform_scan(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __last - __first,
-        [__first, __unary_op](_DifferenceType __i) mutable { return __unary_op(__first[__i]); },
-        __init,
-        __binary_op,
-        [__first, __unary_op, __binary_op](_DifferenceType __i, _DifferenceType __j, _Tp __init) {
-          // Execute serial __brick_transform_reduce, due to the explicit SIMD vectorization (reduction) requires a
-          // commutative operation for the guarantee of correct scan.
-          return __internal::__brick_transform_reduce(
-              __first + __i,
-              __first + __j,
-              __init,
-              __binary_op,
-              __unary_op,
-              /*__is_vector*/ std::false_type());
-        },
-        [__first, __unary_op, __binary_op, __result](_DifferenceType __i, _DifferenceType __j, _Tp __init) {
-          return __internal::__brick_transform_scan(
-                     __first + __i,
-                     __first + __j,
-                     __result + __i,
-                     __unary_op,
-                     __init,
-                     __binary_op,
-                     _Inclusive(),
-                     _IsVector{})
-              .second;
-        });
-    return __result + (__last - __first);
-  });
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator,
-          class _OutputIterator,
-          class _UnaryOperation,
-          class _Tp,
-          class _BinaryOperation,
-          class _Inclusive>
-typename std::enable_if<std::is_floating_point<_Tp>::value, _OutputIterator>::type __pattern_transform_scan(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator __first,
-    _RandomAccessIterator __last,
-    _OutputIterator __result,
-    _UnaryOperation __unary_op,
-    _Tp __init,
-    _BinaryOperation __binary_op,
-    _Inclusive) {
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  typedef typename std::iterator_traits<_RandomAccessIterator>::
diff erence_type _DifferenceType;
-  _DifferenceType __n = __last - __first;
-
-  if (__n <= 0) {
-    return __result;
-  }
-  return __internal::__except_handler([&]() {
-    __par_backend::__parallel_strict_scan(
-        __backend_tag{},
-        std::forward<_ExecutionPolicy>(__exec),
-        __n,
-        __init,
-        [__first, __unary_op, __binary_op, __result](_DifferenceType __i, _DifferenceType __len) {
-          return __internal::__brick_transform_scan(
-                     __first + __i,
-                     __first + (__i + __len),
-                     __result + __i,
-                     __unary_op,
-                     _Tp{},
-                     __binary_op,
-                     _Inclusive(),
-                     _IsVector{})
-              .second;
-        },
-        __binary_op,
-        [__result, &__binary_op](_DifferenceType __i, _DifferenceType __len, _Tp __initial) {
-          return *(std::transform(__result + __i,
-                                  __result + __i + __len,
-                                  __result + __i,
-                                  [&__initial, &__binary_op](const _Tp& __x) {
-                                    return __binary_op(__initial, __x);
-                                  }) -
-                   1);
-        },
-        [](_Tp) {});
-    return __result + (__last - __first);
-  });
-}
-
-//------------------------------------------------------------------------
-// adjacent_
diff erence
-//------------------------------------------------------------------------
-
-template <class _ForwardIterator, class _OutputIterator, class _BinaryOperation>
-_OutputIterator __brick_adjacent_
diff erence(
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _OutputIterator __d_first,
-    _BinaryOperation __op,
-    /*is_vector*/ std::false_type) noexcept {
-  return std::adjacent_
diff erence(__first, __last, __d_first, __op);
-}
-
-template <class _RandomAccessIterator1, class _RandomAccessIterator2, class BinaryOperation>
-_RandomAccessIterator2 __brick_adjacent_
diff erence(
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __d_first,
-    BinaryOperation __op,
-    /*is_vector=*/std::true_type) noexcept {
-  _LIBCPP_ASSERT_UNCATEGORIZED(__first != __last, "Range cannot be empty");
-
-  typedef typename std::iterator_traits<_RandomAccessIterator1>::reference _ReferenceType1;
-  typedef typename std::iterator_traits<_RandomAccessIterator2>::reference _ReferenceType2;
-
-  auto __n   = __last - __first;
-  *__d_first = *__first;
-  return __unseq_backend::__simd_walk_3(
-      __first + 1,
-      __n - 1,
-      __first,
-      __d_first + 1,
-      [&__op](_ReferenceType1 __x, _ReferenceType1 __y, _ReferenceType2 __z) { __z = __op(__x, __y); });
-}
-
-template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _OutputIterator, class _BinaryOperation>
-_OutputIterator __pattern_adjacent_
diff erence(
-    _Tag,
-    _ExecutionPolicy&&,
-    _ForwardIterator __first,
-    _ForwardIterator __last,
-    _OutputIterator __d_first,
-    _BinaryOperation __op) noexcept {
-  return __internal::__brick_adjacent_
diff erence(__first, __last, __d_first, __op, typename _Tag::__is_vector{});
-}
-
-template <class _IsVector,
-          class _ExecutionPolicy,
-          class _RandomAccessIterator1,
-          class _RandomAccessIterator2,
-          class _BinaryOperation>
-_RandomAccessIterator2 __pattern_adjacent_
diff erence(
-    __parallel_tag<_IsVector> __tag,
-    _ExecutionPolicy&& __exec,
-    _RandomAccessIterator1 __first,
-    _RandomAccessIterator1 __last,
-    _RandomAccessIterator2 __d_first,
-    _BinaryOperation __op) {
-  _LIBCPP_ASSERT_UNCATEGORIZED(__first != __last, "range cannot be empty");
-  typedef typename std::iterator_traits<_RandomAccessIterator1>::reference _ReferenceType1;
-  typedef typename std::iterator_traits<_RandomAccessIterator2>::reference _ReferenceType2;
-
-  using __backend_tag = typename decltype(__tag)::__backend_tag;
-
-  *__d_first = *__first;
-  __par_backend::__parallel_for(
-      __backend_tag{},
-      std::forward<_ExecutionPolicy>(__exec),
-      __first,
-      __last - 1,
-      [&__op, __d_first, __first](_RandomAccessIterator1 __b, _RandomAccessIterator1 __e) {
-        _RandomAccessIterator2 __d_b = __d_first + (__b - __first);
-        __internal::__brick_walk3(
-            __b,
-            __e,
-            __b + 1,
-            __d_b + 1,
-            [&__op](_ReferenceType1 __x, _ReferenceType1 __y, _ReferenceType2 __z) { __z = __op(__y, __x); },
-            _IsVector{});
-      });
-  return __d_first + (__last - __first);
-}
-
-} // namespace __internal
-} // namespace __pstl
-
-#endif /* _PSTL_NUMERIC_IMPL_H */

diff  --git a/libcxx/include/__pstl/internal/omp/parallel_for.h b/libcxx/include/__pstl/internal/omp/parallel_for.h
deleted file mode 100644
index 0f841e53118107..00000000000000
--- a/libcxx/include/__pstl/internal/omp/parallel_for.h
+++ /dev/null
@@ -1,64 +0,0 @@
-// -*- C++ -*-
-// -*-===----------------------------------------------------------------------===//
-//
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_INTERNAL_OMP_PARALLEL_FOR_H
-#define _PSTL_INTERNAL_OMP_PARALLEL_FOR_H
-
-#include <cstddef>
-
-#include "util.h"
-
-namespace __pstl
-{
-namespace __omp_backend
-{
-
-template <class _Index, class _Fp>
-void
-__parallel_for_body(_Index __first, _Index __last, _Fp __f)
-{
-    // initial partition of the iteration space into chunks
-    auto __policy = __omp_backend::__chunk_partitioner(__first, __last);
-
-    // To avoid over-subscription we use taskloop for the nested parallelism
-    _PSTL_PRAGMA(omp taskloop untied mergeable)
-    for (std::size_t __chunk = 0; __chunk < __policy.__n_chunks; ++__chunk)
-    {
-        __pstl::__omp_backend::__process_chunk(__policy, __first, __chunk, __f);
-    }
-}
-
-//------------------------------------------------------------------------
-// Notation:
-// Evaluation of brick f[i,j) for each subrange [i,j) of [first, last)
-//------------------------------------------------------------------------
-
-template <class _ExecutionPolicy, class _Index, class _Fp>
-void
-__parallel_for(__pstl::__internal::__openmp_backend_tag, _ExecutionPolicy&&, _Index __first, _Index __last, _Fp __f)
-{
-    if (omp_in_parallel())
-    {
-        // we don't create a nested parallel region in an existing parallel
-        // region: just create tasks
-        __pstl::__omp_backend::__parallel_for_body(__first, __last, __f);
-    }
-    else
-    {
-        // in any case (nested or non-nested) one parallel region is created and
-        // only one thread creates a set of tasks
-        _PSTL_PRAGMA(omp parallel)
-        _PSTL_PRAGMA(omp single nowait) { __pstl::__omp_backend::__parallel_for_body(__first, __last, __f); }
-    }
-}
-
-} // namespace __omp_backend
-} // namespace __pstl
-#endif // _PSTL_INTERNAL_OMP_PARALLEL_FOR_H

diff  --git a/libcxx/include/__pstl/internal/omp/parallel_for_each.h b/libcxx/include/__pstl/internal/omp/parallel_for_each.h
deleted file mode 100644
index b9bfb05930a194..00000000000000
--- a/libcxx/include/__pstl/internal/omp/parallel_for_each.h
+++ /dev/null
@@ -1,59 +0,0 @@
-// -*- C++ -*-
-// -*-===----------------------------------------------------------------------===//
-//
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_INTERNAL_OMP_PARALLEL_FOR_EACH_H
-#define _PSTL_INTERNAL_OMP_PARALLEL_FOR_EACH_H
-
-#include "util.h"
-
-namespace __pstl
-{
-namespace __omp_backend
-{
-
-template <class _ForwardIterator, class _Fp>
-void
-__parallel_for_each_body(_ForwardIterator __first, _ForwardIterator __last, _Fp __f)
-{
-    using DifferenceType = typename std::iterator_traits<_ForwardIterator>::
diff erence_type;
-    // TODO: Think of an approach to remove the std::distance call
-    auto __size = std::distance(__first, __last);
-
-    _PSTL_PRAGMA(omp taskloop untied mergeable)
-    for (DifferenceType __index = 0; __index < __size; ++__index)
-    {
-        // TODO: Think of an approach to remove the increment here each time.
-        auto __iter = std::next(__first, __index);
-        __f(*__iter);
-    }
-}
-
-template <class _ExecutionPolicy, class _ForwardIterator, class _Fp>
-void
-__parallel_for_each(_ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last, _Fp __f)
-{
-    if (omp_in_parallel())
-    {
-        // we don't create a nested parallel region in an existing parallel
-        // region: just create tasks
-        __pstl::__omp_backend::__parallel_for_each_body(__first, __last, __f);
-    }
-    else
-    {
-        // in any case (nested or non-nested) one parallel region is created and
-        // only one thread creates a set of tasks
-        _PSTL_PRAGMA(omp parallel)
-        _PSTL_PRAGMA(omp single nowait) { __pstl::__omp_backend::__parallel_for_each_body(__first, __last, __f); }
-    }
-}
-
-} // namespace __omp_backend
-} // namespace __pstl
-#endif // _PSTL_INTERNAL_OMP_PARALLEL_FOR_EACH_H

diff  --git a/libcxx/include/__pstl/internal/omp/parallel_invoke.h b/libcxx/include/__pstl/internal/omp/parallel_invoke.h
deleted file mode 100644
index 045ccbe9a18cb4..00000000000000
--- a/libcxx/include/__pstl/internal/omp/parallel_invoke.h
+++ /dev/null
@@ -1,50 +0,0 @@
-// -*- C++ -*-
-// -*-===----------------------------------------------------------------------===//
-//
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_INTERNAL_OMP_PARALLEL_INVOKE_H
-#define _PSTL_INTERNAL_OMP_PARALLEL_INVOKE_H
-
-#include "util.h"
-
-namespace __pstl
-{
-namespace __omp_backend
-{
-
-template <typename _F1, typename _F2>
-void
-__parallel_invoke_body(_F1&& __f1, _F2&& __f2)
-{
-    _PSTL_PRAGMA(omp taskgroup)
-    {
-        _PSTL_PRAGMA(omp task untied mergeable) { std::forward<_F1>(__f1)(); }
-        _PSTL_PRAGMA(omp task untied mergeable) { std::forward<_F2>(__f2)(); }
-    }
-}
-
-template <class _ExecutionPolicy, typename _F1, typename _F2>
-void
-__parallel_invoke(__pstl::__internal::__openmp_backend_tag, _ExecutionPolicy&&, _F1&& __f1, _F2&& __f2)
-{
-    if (omp_in_parallel())
-    {
-        __pstl::__omp_backend::__parallel_invoke_body(std::forward<_F1>(__f1), std::forward<_F2>(__f2));
-    }
-    else
-    {
-        _PSTL_PRAGMA(omp parallel)
-        _PSTL_PRAGMA(omp single nowait)
-        __pstl::__omp_backend::__parallel_invoke_body(std::forward<_F1>(__f1), std::forward<_F2>(__f2));
-    }
-}
-
-} // namespace __omp_backend
-} // namespace __pstl
-#endif // _PSTL_INTERNAL_OMP_PARALLEL_INVOKE_H

diff  --git a/libcxx/include/__pstl/internal/omp/parallel_merge.h b/libcxx/include/__pstl/internal/omp/parallel_merge.h
deleted file mode 100644
index e6f82c5e1866c5..00000000000000
--- a/libcxx/include/__pstl/internal/omp/parallel_merge.h
+++ /dev/null
@@ -1,98 +0,0 @@
-// -*- C++ -*-
-// -*-===----------------------------------------------------------------------===//
-//
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_INTERNAL_OMP_PARALLEL_MERGE_H
-#define _PSTL_INTERNAL_OMP_PARALLEL_MERGE_H
-
-#include "util.h"
-
-namespace __pstl
-{
-namespace __omp_backend
-{
-
-template <typename _RandomAccessIterator1, typename _RandomAccessIterator2, typename _RandomAccessIterator3,
-          typename _Compare, typename _LeafMerge>
-void
-__parallel_merge_body(std::size_t __size_x, std::size_t __size_y, _RandomAccessIterator1 __xs,
-                      _RandomAccessIterator1 __xe, _RandomAccessIterator2 __ys, _RandomAccessIterator2 __ye,
-                      _RandomAccessIterator3 __zs, _Compare __comp, _LeafMerge __leaf_merge)
-{
-
-    if (__size_x + __size_y <= __omp_backend::__default_chunk_size)
-    {
-        __leaf_merge(__xs, __xe, __ys, __ye, __zs, __comp);
-        return;
-    }
-
-    _RandomAccessIterator1 __xm;
-    _RandomAccessIterator2 __ym;
-
-    if (__size_x < __size_y)
-    {
-        __ym = __ys + (__size_y / 2);
-        __xm = std::upper_bound(__xs, __xe, *__ym, __comp);
-    }
-    else
-    {
-        __xm = __xs + (__size_x / 2);
-        __ym = std::lower_bound(__ys, __ye, *__xm, __comp);
-    }
-
-    auto __zm = __zs + (__xm - __xs) + (__ym - __ys);
-
-    _PSTL_PRAGMA(omp task untied mergeable default(none)
-                     firstprivate(__xs, __xm, __ys, __ym, __zs, __comp, __leaf_merge))
-    __pstl::__omp_backend::__parallel_merge_body(__xm - __xs, __ym - __ys, __xs, __xm, __ys, __ym, __zs, __comp,
-                                                      __leaf_merge);
-
-    _PSTL_PRAGMA(omp task untied mergeable default(none)
-                     firstprivate(__xm, __xe, __ym, __ye, __zm, __comp, __leaf_merge))
-    __pstl::__omp_backend::__parallel_merge_body(__xe - __xm, __ye - __ym, __xm, __xe, __ym, __ye, __zm, __comp,
-                                                      __leaf_merge);
-
-    _PSTL_PRAGMA(omp taskwait)
-}
-
-template <class _ExecutionPolicy, typename _RandomAccessIterator1, typename _RandomAccessIterator2,
-          typename _RandomAccessIterator3, typename _Compare, typename _LeafMerge>
-void
-__parallel_merge(__pstl::__internal::__openmp_backend_tag, _ExecutionPolicy&& /*__exec*/, _RandomAccessIterator1 __xs,
-                 _RandomAccessIterator1 __xe, _RandomAccessIterator2 __ys, _RandomAccessIterator2 __ye,
-                 _RandomAccessIterator3 __zs, _Compare __comp, _LeafMerge __leaf_merge)
-
-{
-    std::size_t __size_x = __xe - __xs;
-    std::size_t __size_y = __ye - __ys;
-
-    /*
-     * Run the merge in parallel by chunking it up. Use the smaller range (if any) as the iteration range, and the
-     * larger range as the search range.
-     */
-
-    if (omp_in_parallel())
-    {
-        __pstl::__omp_backend::__parallel_merge_body(__size_x, __size_y, __xs, __xe, __ys, __ye, __zs, __comp,
-                                                          __leaf_merge);
-    }
-    else
-    {
-        _PSTL_PRAGMA(omp parallel)
-        {
-            _PSTL_PRAGMA(omp single nowait)
-            __pstl::__omp_backend::__parallel_merge_body(__size_x, __size_y, __xs, __xe, __ys, __ye, __zs, __comp,
-                                                              __leaf_merge);
-        }
-    }
-}
-
-} // namespace __omp_backend
-} // namespace __pstl
-#endif // _PSTL_INTERNAL_OMP_PARALLEL_MERGE_H

diff  --git a/libcxx/include/__pstl/internal/omp/parallel_reduce.h b/libcxx/include/__pstl/internal/omp/parallel_reduce.h
deleted file mode 100644
index 841d48fc30515f..00000000000000
--- a/libcxx/include/__pstl/internal/omp/parallel_reduce.h
+++ /dev/null
@@ -1,73 +0,0 @@
-// -*- C++ -*-
-// -*-===----------------------------------------------------------------------===//
-//
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_INTERNAL_OMP_PARALLEL_REDUCE_H
-#define _PSTL_INTERNAL_OMP_PARALLEL_REDUCE_H
-
-#include "util.h"
-
-namespace __pstl
-{
-namespace __omp_backend
-{
-
-template <class _RandomAccessIterator, class _Value, typename _RealBody, typename _Reduction>
-_Value
-__parallel_reduce_body(_RandomAccessIterator __first, _RandomAccessIterator __last, _Value __identity,
-                       _RealBody __real_body, _Reduction __reduce)
-{
-    if (__should_run_serial(__first, __last))
-    {
-        return __real_body(__first, __last, __identity);
-    }
-
-    auto __middle = __first + ((__last - __first) / 2);
-    _Value __v1(__identity), __v2(__identity);
-    __parallel_invoke_body(
-        [&]() { __v1 = __parallel_reduce_body(__first, __middle, __identity, __real_body, __reduce); },
-        [&]() { __v2 = __parallel_reduce_body(__middle, __last, __identity, __real_body, __reduce); });
-
-    return __reduce(__v1, __v2);
-}
-
-//------------------------------------------------------------------------
-// Notation:
-//      r(i,j,init) returns reduction of init with reduction over [i,j)
-//      c(x,y) combines values x and y that were the result of r
-//------------------------------------------------------------------------
-
-template <class _ExecutionPolicy, class _RandomAccessIterator, class _Value, typename _RealBody, typename _Reduction>
-_Value
-__parallel_reduce(__pstl::__internal::__openmp_backend_tag, _ExecutionPolicy&&, _RandomAccessIterator __first,
-                  _RandomAccessIterator __last, _Value __identity, _RealBody __real_body, _Reduction __reduction)
-{
-    // We don't create a nested parallel region in an existing parallel region:
-    // just create tasks.
-    if (omp_in_parallel())
-    {
-        return __pstl::__omp_backend::__parallel_reduce_body(__first, __last, __identity, __real_body, __reduction);
-    }
-
-    // In any case (nested or non-nested) one parallel region is created and only
-    // one thread creates a set of tasks.
-    _Value __res = __identity;
-
-    _PSTL_PRAGMA(omp parallel)
-    _PSTL_PRAGMA(omp single nowait)
-    {
-        __res = __pstl::__omp_backend::__parallel_reduce_body(__first, __last, __identity, __real_body, __reduction);
-    }
-
-    return __res;
-}
-
-} // namespace __omp_backend
-} // namespace __pstl
-#endif // _PSTL_INTERNAL_OMP_PARALLEL_REDUCE_H

diff  --git a/libcxx/include/__pstl/internal/omp/parallel_scan.h b/libcxx/include/__pstl/internal/omp/parallel_scan.h
deleted file mode 100644
index f3eb967ca4fb2e..00000000000000
--- a/libcxx/include/__pstl/internal/omp/parallel_scan.h
+++ /dev/null
@@ -1,136 +0,0 @@
-// -*- C++ -*-
-// -*-===----------------------------------------------------------------------===//
-//
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_INTERNAL_OMP_PARALLEL_SCAN_H
-#define _PSTL_INTERNAL_OMP_PARALLEL_SCAN_H
-
-#include "parallel_invoke.h"
-
-namespace __pstl
-{
-namespace __omp_backend
-{
-
-template <typename _Index>
-_Index
-__split(_Index __m)
-{
-    _Index __k = 1;
-    while (2 * __k < __m)
-        __k *= 2;
-    return __k;
-}
-
-template <typename _Index, typename _Tp, typename _Rp, typename _Cp>
-void
-__upsweep(_Index __i, _Index __m, _Index __tilesize, _Tp* __r, _Index __lastsize, _Rp __reduce, _Cp __combine)
-{
-    if (__m == 1)
-        __r[0] = __reduce(__i * __tilesize, __lastsize);
-    else
-    {
-        _Index __k = __split(__m);
-        __omp_backend::__parallel_invoke_body(
-            [=] { __omp_backend::__upsweep(__i, __k, __tilesize, __r, __tilesize, __reduce, __combine); },
-            [=] {
-                __omp_backend::__upsweep(__i + __k, __m - __k, __tilesize, __r + __k, __lastsize, __reduce, __combine);
-            });
-        if (__m == 2 * __k)
-            __r[__m - 1] = __combine(__r[__k - 1], __r[__m - 1]);
-    }
-}
-
-template <typename _Index, typename _Tp, typename _Cp, typename _Sp>
-void
-__downsweep(_Index __i, _Index __m, _Index __tilesize, _Tp* __r, _Index __lastsize, _Tp __initial, _Cp __combine,
-            _Sp __scan)
-{
-    if (__m == 1)
-        __scan(__i * __tilesize, __lastsize, __initial);
-    else
-    {
-        const _Index __k = __split(__m);
-        __omp_backend::__parallel_invoke_body(
-            [=] { __omp_backend::__downsweep(__i, __k, __tilesize, __r, __tilesize, __initial, __combine, __scan); },
-            // Assumes that __combine never throws.
-            // TODO: Consider adding a requirement for user functors to be constant.
-            [=, &__combine]
-            {
-                __omp_backend::__downsweep(__i + __k, __m - __k, __tilesize, __r + __k, __lastsize,
-                                           __combine(__initial, __r[__k - 1]), __combine, __scan);
-            });
-    }
-}
-
-template <typename _ExecutionPolicy, typename _Index, typename _Tp, typename _Rp, typename _Cp, typename _Sp,
-          typename _Ap>
-void
-__parallel_strict_scan_body(_Index __n, _Tp __initial, _Rp __reduce, _Cp __combine, _Sp __scan, _Ap __apex)
-{
-    _Index __p = omp_get_num_threads();
-    const _Index __slack = 4;
-    _Index __tilesize = (__n - 1) / (__slack * __p) + 1;
-    _Index __m = (__n - 1) / __tilesize;
-    __buffer<_Tp> __buf(__m + 1);
-    _Tp* __r = __buf.get();
-
-    __omp_backend::__upsweep(_Index(0), _Index(__m + 1), __tilesize, __r, __n - __m * __tilesize, __reduce, __combine);
-
-    std::size_t __k = __m + 1;
-    _Tp __t = __r[__k - 1];
-    while ((__k &= __k - 1))
-    {
-        __t = __combine(__r[__k - 1], __t);
-    }
-
-    __apex(__combine(__initial, __t));
-    __omp_backend::__downsweep(_Index(0), _Index(__m + 1), __tilesize, __r, __n - __m * __tilesize, __initial,
-                               __combine, __scan);
-}
-
-template <class _ExecutionPolicy, typename _Index, typename _Tp, typename _Rp, typename _Cp, typename _Sp, typename _Ap>
-void
-__parallel_strict_scan(__pstl::__internal::__openmp_backend_tag, _ExecutionPolicy&&, _Index __n, _Tp __initial,
-                       _Rp __reduce, _Cp __combine, _Sp __scan, _Ap __apex)
-{
-    if (__n <= __default_chunk_size)
-    {
-        _Tp __sum = __initial;
-        if (__n)
-        {
-            __sum = __combine(__sum, __reduce(_Index(0), __n));
-        }
-        __apex(__sum);
-        if (__n)
-        {
-            __scan(_Index(0), __n, __initial);
-        }
-        return;
-    }
-
-    if (omp_in_parallel())
-    {
-        __pstl::__omp_backend::__parallel_strict_scan_body<_ExecutionPolicy>(__n, __initial, __reduce, __combine,
-                                                                             __scan, __apex);
-    }
-    else
-    {
-        _PSTL_PRAGMA(omp parallel)
-        _PSTL_PRAGMA(omp single nowait)
-        {
-            __pstl::__omp_backend::__parallel_strict_scan_body<_ExecutionPolicy>(__n, __initial, __reduce, __combine,
-                                                                                 __scan, __apex);
-        }
-    }
-}
-
-} // namespace __omp_backend
-} // namespace __pstl
-#endif // _PSTL_INTERNAL_OMP_PARALLEL_SCAN_H

diff  --git a/libcxx/include/__pstl/internal/omp/parallel_stable_partial_sort.h b/libcxx/include/__pstl/internal/omp/parallel_stable_partial_sort.h
deleted file mode 100644
index 06cd55bb4899b7..00000000000000
--- a/libcxx/include/__pstl/internal/omp/parallel_stable_partial_sort.h
+++ /dev/null
@@ -1,33 +0,0 @@
-// -*- C++ -*-
-// -*-===----------------------------------------------------------------------===//
-//
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_INTERNAL_OMP_PARALLEL_STABLE_PARTIAL_SORT_H
-#define _PSTL_INTERNAL_OMP_PARALLEL_STABLE_PARTIAL_SORT_H
-
-#include "util.h"
-
-namespace __pstl
-{
-namespace __omp_backend
-{
-
-template <typename _RandomAccessIterator, typename _Compare, typename _LeafSort>
-void
-__parallel_stable_partial_sort(__pstl::__internal::__openmp_backend_tag, _RandomAccessIterator __xs,
-                               _RandomAccessIterator __xe, _Compare __comp, _LeafSort __leaf_sort,
-                               std::size_t /* __nsort */)
-{
-    // TODO: "Parallel partial sort needs to be implemented.");
-    __leaf_sort(__xs, __xe, __comp);
-}
-
-} // namespace __omp_backend
-} // namespace __pstl
-#endif // _PSTL_INTERNAL_OMP_PARALLEL_STABLE_PARTIAL_SORT_H

diff  --git a/libcxx/include/__pstl/internal/omp/parallel_stable_sort.h b/libcxx/include/__pstl/internal/omp/parallel_stable_sort.h
deleted file mode 100644
index e4d0676627260f..00000000000000
--- a/libcxx/include/__pstl/internal/omp/parallel_stable_sort.h
+++ /dev/null
@@ -1,160 +0,0 @@
-// -*- C++ -*-
-// -*-===----------------------------------------------------------------------===//
-//
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_INTERNAL_OMP_PARALLEL_STABLE_SORT_H
-#define _PSTL_INTERNAL_OMP_PARALLEL_STABLE_SORT_H
-
-#include "util.h"
-#include "parallel_merge.h"
-
-namespace __pstl
-{
-namespace __omp_backend
-{
-
-namespace __sort_details
-{
-struct __move_value
-{
-    template <typename _Iterator, typename _OutputIterator>
-    void
-    operator()(_Iterator __x, _OutputIterator __z) const
-    {
-        *__z = std::move(*__x);
-    }
-};
-
-template <typename _RandomAccessIterator, typename _OutputIterator>
-_OutputIterator
-__parallel_move_range(_RandomAccessIterator __first1, _RandomAccessIterator __last1, _OutputIterator __d_first)
-{
-    std::size_t __size = __last1 - __first1;
-
-    // Perform serial moving of small chunks
-
-    if (__size <= __default_chunk_size)
-    {
-        return std::move(__first1, __last1, __d_first);
-    }
-
-    // Perform parallel moving of larger chunks
-    auto __policy = __pstl::__omp_backend::__chunk_partitioner(__first1, __last1);
-
-    _PSTL_PRAGMA(omp taskloop)
-    for (std::size_t __chunk = 0; __chunk < __policy.__n_chunks; ++__chunk)
-    {
-        __pstl::__omp_backend::__process_chunk(__policy, __first1, __chunk,
-                                       [&](auto __chunk_first, auto __chunk_last)
-                                       {
-                                           auto __chunk_offset = __chunk_first - __first1;
-                                           auto __output_it = __d_first + __chunk_offset;
-                                           std::move(__chunk_first, __chunk_last, __output_it);
-                                       });
-    }
-
-    return __d_first + __size;
-}
-
-struct __move_range
-{
-    template <typename _RandomAccessIterator, typename _OutputIterator>
-    _OutputIterator
-    operator()(_RandomAccessIterator __first1, _RandomAccessIterator __last1, _OutputIterator __d_first) const
-    {
-        return __pstl::__omp_backend::__sort_details::__parallel_move_range(__first1, __last1, __d_first);
-    }
-};
-} // namespace __sort_details
-
-template <typename _RandomAccessIterator, typename _Compare, typename _LeafSort>
-void
-__parallel_stable_sort_body(_RandomAccessIterator __xs, _RandomAccessIterator __xe, _Compare __comp,
-                            _LeafSort __leaf_sort)
-{
-    using _ValueType = typename std::iterator_traits<_RandomAccessIterator>::value_type;
-    using _VecType = typename std::vector<_ValueType>;
-    using _OutputIterator = typename _VecType::iterator;
-    using _MoveValue = typename __omp_backend::__sort_details::__move_value;
-    using _MoveRange = __omp_backend::__sort_details::__move_range;
-
-    if (__should_run_serial(__xs, __xe))
-    {
-        __leaf_sort(__xs, __xe, __comp);
-    }
-    else
-    {
-        std::size_t __size = __xe - __xs;
-        auto __mid = __xs + (__size / 2);
-        __pstl::__omp_backend::__parallel_invoke_body(
-            [&]() { __parallel_stable_sort_body(__xs, __mid, __comp, __leaf_sort); },
-            [&]() { __parallel_stable_sort_body(__mid, __xe, __comp, __leaf_sort); });
-
-        // Perform a parallel merge of the sorted ranges into __output_data.
-        _VecType __output_data(__size);
-        _MoveValue __move_value;
-        _MoveRange __move_range;
-        __utils::__serial_move_merge __merge(__size);
-        __pstl::__omp_backend::__parallel_merge_body(
-            __mid - __xs, __xe - __mid, __xs, __mid, __mid, __xe, __output_data.begin(), __comp,
-            [&__merge, &__move_value, &__move_range](_RandomAccessIterator __as, _RandomAccessIterator __ae,
-                                                     _RandomAccessIterator __bs, _RandomAccessIterator __be,
-                                                     _OutputIterator __cs, _Compare __comp)
-            { __merge(__as, __ae, __bs, __be, __cs, __comp, __move_value, __move_value, __move_range, __move_range); });
-
-        // Move the values from __output_data back in the original source range.
-        __pstl::__omp_backend::__sort_details::__parallel_move_range(__output_data.begin(), __output_data.end(), __xs);
-    }
-}
-
-template <class _ExecutionPolicy, typename _RandomAccessIterator, typename _Compare, typename _LeafSort>
-void
-__parallel_stable_sort(__pstl::__internal::__openmp_backend_tag __tag, _ExecutionPolicy&& /*__exec*/,
-                       _RandomAccessIterator __xs, _RandomAccessIterator __xe, _Compare __comp, _LeafSort __leaf_sort,
-                       std::size_t __nsort = 0)
-{
-    auto __count = static_cast<std::size_t>(__xe - __xs);
-    if (__count <= __default_chunk_size || __nsort < __count)
-    {
-        __leaf_sort(__xs, __xe, __comp);
-        return;
-    }
-
-    // TODO: the partial sort implementation should
-    // be shared with the other backends.
-
-    if (omp_in_parallel())
-    {
-        if (__count <= __nsort)
-        {
-            __pstl::__omp_backend::__parallel_stable_sort_body(__xs, __xe, __comp, __leaf_sort);
-        }
-        else
-        {
-            __pstl::__omp_backend::__parallel_stable_partial_sort(__tag, __xs, __xe, __comp, __leaf_sort, __nsort);
-        }
-    }
-    else
-    {
-        _PSTL_PRAGMA(omp parallel)
-        _PSTL_PRAGMA(omp single nowait)
-        if (__count <= __nsort)
-        {
-            __pstl::__omp_backend::__parallel_stable_sort_body(__xs, __xe, __comp, __leaf_sort);
-        }
-        else
-        {
-            __pstl::__omp_backend::__parallel_stable_partial_sort(__tag, __xs, __xe, __comp, __leaf_sort, __nsort);
-        }
-    }
-}
-
-} // namespace __omp_backend
-} // namespace __pstl
-#endif // _PSTL_INTERNAL_OMP_PARALLEL_STABLE_SORT_H

diff  --git a/libcxx/include/__pstl/internal/omp/parallel_transform_reduce.h b/libcxx/include/__pstl/internal/omp/parallel_transform_reduce.h
deleted file mode 100644
index 1d4cc0a5974d29..00000000000000
--- a/libcxx/include/__pstl/internal/omp/parallel_transform_reduce.h
+++ /dev/null
@@ -1,113 +0,0 @@
-// -*- C++ -*-
-// -*-===----------------------------------------------------------------------===//
-//
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_INTERNAL_OMP_PARALLEL_TRANSFORM_REDUCE_H
-#define _PSTL_INTERNAL_OMP_PARALLEL_TRANSFORM_REDUCE_H
-
-#include "util.h"
-
-namespace __pstl
-{
-namespace __omp_backend
-{
-
-//------------------------------------------------------------------------
-// parallel_transform_reduce
-//
-// Notation:
-//      r(i,j,init) returns reduction of init with reduction over [i,j)
-//      u(i) returns f(i,i+1,identity) for a hypothetical left identity element
-//      of r c(x,y) combines values x and y that were the result of r or u
-//------------------------------------------------------------------------
-
-template <class _RandomAccessIterator, class _UnaryOp, class _Value, class _Combiner, class _Reduction>
-auto
-__transform_reduce_body(_RandomAccessIterator __first, _RandomAccessIterator __last, _UnaryOp __unary_op, _Value __init,
-                        _Combiner __combiner, _Reduction __reduction)
-{
-    const std::size_t __num_threads = omp_get_num_threads();
-    const std::size_t __size = __last - __first;
-
-    // Initial partition of the iteration space into chunks. If the range is too small,
-    // this will result in a nonsense policy, so we check on the size as well below.
-    auto __policy = __omp_backend::__chunk_partitioner(__first + __num_threads, __last);
-
-    if (__size <= __num_threads || __policy.__n_chunks < 2)
-    {
-        return __reduction(__first, __last, __init);
-    }
-
-    // Here, we cannot use OpenMP UDR because we must store the init value in
-    // the combiner and it will be used several times. Although there should be
-    // the only one; we manually generate the identity elements for each thread.
-    std::vector<_Value> __accums;
-    __accums.reserve(__num_threads);
-
-    // initialize accumulators for all threads
-    for (std::size_t __i = 0; __i < __num_threads; ++__i)
-    {
-        __accums.emplace_back(__unary_op(__first + __i));
-    }
-
-    // main loop
-    _PSTL_PRAGMA(omp taskloop shared(__accums))
-    for (std::size_t __chunk = 0; __chunk < __policy.__n_chunks; ++__chunk)
-    {
-        __pstl::__omp_backend::__process_chunk(__policy, __first + __num_threads, __chunk,
-                                       [&](auto __chunk_first, auto __chunk_last)
-                                       {
-                                           auto __thread_num = omp_get_thread_num();
-                                           __accums[__thread_num] =
-                                               __reduction(__chunk_first, __chunk_last, __accums[__thread_num]);
-                                       });
-    }
-
-    // combine by accumulators
-    for (std::size_t __i = 0; __i < __num_threads; ++__i)
-    {
-        __init = __combiner(__init, __accums[__i]);
-    }
-
-    return __init;
-}
-
-template <class _ExecutionPolicy, class _RandomAccessIterator, class _UnaryOp, class _Value, class _Combiner,
-          class _Reduction>
-_Value
-__parallel_transform_reduce(__pstl::__internal::__openmp_backend_tag, _ExecutionPolicy&&, _RandomAccessIterator __first,
-                            _RandomAccessIterator __last, _UnaryOp __unary_op, _Value __init, _Combiner __combiner,
-                            _Reduction __reduction)
-{
-    _Value __result = __init;
-    if (omp_in_parallel())
-    {
-        // We don't create a nested parallel region in an existing parallel
-        // region: just create tasks
-        __result = __pstl::__omp_backend::__transform_reduce_body(__first, __last, __unary_op, __init, __combiner,
-                                                                  __reduction);
-    }
-    else
-    {
-        // Create a parallel region, and a single thread will create tasks
-        // for the region.
-        _PSTL_PRAGMA(omp parallel)
-        _PSTL_PRAGMA(omp single nowait)
-        {
-            __result = __pstl::__omp_backend::__transform_reduce_body(__first, __last, __unary_op, __init, __combiner,
-                                                                      __reduction);
-        }
-    }
-
-    return __result;
-}
-
-} // namespace __omp_backend
-} // namespace __pstl
-#endif // _PSTL_INTERNAL_OMP_PARALLEL_TRANSFORM_REDUCE_H

diff  --git a/libcxx/include/__pstl/internal/omp/parallel_transform_scan.h b/libcxx/include/__pstl/internal/omp/parallel_transform_scan.h
deleted file mode 100644
index f83628994bc216..00000000000000
--- a/libcxx/include/__pstl/internal/omp/parallel_transform_scan.h
+++ /dev/null
@@ -1,32 +0,0 @@
-// -*- C++ -*-
-// -*-===----------------------------------------------------------------------===//
-//
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_INTERNAL_OMP_PARALLEL_TRANSFORM_SCAN_H
-#define _PSTL_INTERNAL_OMP_PARALLEL_TRANSFORM_SCAN_H
-
-#include "util.h"
-
-namespace __pstl
-{
-namespace __omp_backend
-{
-
-template <class _ExecutionPolicy, class _Index, class _Up, class _Tp, class _Cp, class _Rp, class _Sp>
-_Tp
-__parallel_transform_scan(__pstl::__internal::__openmp_backend_tag, _ExecutionPolicy&&, _Index __n, _Up /* __u */,
-                          _Tp __init, _Cp /* __combine */, _Rp /* __brick_reduce */, _Sp __scan)
-{
-    // TODO: parallelize this function.
-    return __scan(_Index(0), __n, __init);
-}
-
-} // namespace __omp_backend
-} // namespace __pstl
-#endif // _PSTL_INTERNAL_OMP_PARALLEL_TRANSFORM_SCAN_H

diff  --git a/libcxx/include/__pstl/internal/omp/util.h b/libcxx/include/__pstl/internal/omp/util.h
deleted file mode 100644
index 3c1a92e03cb950..00000000000000
--- a/libcxx/include/__pstl/internal/omp/util.h
+++ /dev/null
@@ -1,171 +0,0 @@
-// -*- C++ -*-
-// -*-===----------------------------------------------------------------------===//
-//
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_INTERNAL_OMP_UTIL_H
-#define _PSTL_INTERNAL_OMP_UTIL_H
-
-#include <algorithm>
-#include <atomic>
-#include <iterator>
-#include <cstddef>
-#include <cstdio>
-#include <memory>
-#include <vector>
-#include <omp.h>
-
-#include "../parallel_backend_utils.h"
-#include "../unseq_backend_simd.h"
-#include "../utils.h"
-
-// Portability "#pragma" definition
-#ifdef _MSC_VER
-#    define _PSTL_PRAGMA(x) __pragma(x)
-#else
-#    define _PSTL_PRAGMA(x) _Pragma(#    x)
-#endif
-
-namespace __pstl
-{
-namespace __omp_backend
-{
-
-//------------------------------------------------------------------------
-// use to cancel execution
-//------------------------------------------------------------------------
-inline void
-__cancel_execution()
-{
-    // TODO: Figure out how to make cancelation work.
-}
-
-//------------------------------------------------------------------------
-// raw buffer
-//------------------------------------------------------------------------
-
-template <typename _Tp>
-class __buffer
-{
-    std::allocator<_Tp> __allocator_;
-    _Tp* __ptr_;
-    const std::size_t __buf_size_;
-    __buffer(const __buffer&) = delete;
-    void
-    operator=(const __buffer&) = delete;
-
-  public:
-    __buffer(std::size_t __n) : __allocator_(), __ptr_(__allocator_.allocate(__n)), __buf_size_(__n) {}
-
-    operator bool() const { return __ptr_ != nullptr; }
-
-    _Tp*
-    get() const
-    {
-        return __ptr_;
-    }
-    ~__buffer() { __allocator_.deallocate(__ptr_, __buf_size_); }
-};
-
-// Preliminary size of each chunk: requires further discussion
-inline constexpr std::size_t __default_chunk_size = 2048;
-
-// Convenience function to determine when we should run serial.
-template <typename _Iterator, std::enable_if_t<!std::is_integral<_Iterator>::value, bool> = true>
-constexpr auto
-__should_run_serial(_Iterator __first, _Iterator __last) -> bool
-{
-    using _
diff erence_type = typename std::iterator_traits<_Iterator>::
diff erence_type;
-    auto __size = std::distance(__first, __last);
-    return __size <= static_cast<_
diff erence_type>(__default_chunk_size);
-}
-
-template <typename _Index, std::enable_if_t<std::is_integral<_Index>::value, bool> = true>
-constexpr auto
-__should_run_serial(_Index __first, _Index __last) -> bool
-{
-    using _
diff erence_type = _Index;
-    auto __size = __last - __first;
-    return __size <= static_cast<_
diff erence_type>(__default_chunk_size);
-}
-
-struct __chunk_metrics
-{
-    std::size_t __n_chunks;
-    std::size_t __chunk_size;
-    std::size_t __first_chunk_size;
-};
-
-// The iteration space partitioner according to __requested_chunk_size
-template <class _RandomAccessIterator, class _Size = std::size_t>
-auto
-__chunk_partitioner(_RandomAccessIterator __first, _RandomAccessIterator __last,
-                    _Size __requested_chunk_size = __default_chunk_size) -> __chunk_metrics
-{
-    /*
-     * This algorithm improves distribution of elements in chunks by avoiding
-     * small tail chunks. The leftover elements that do not fit neatly into
-     * the chunk size are redistributed to early chunks. This improves
-     * utilization of the processor's prefetch and reduces the number of
-     * tasks needed by 1.
-     */
-
-    const _Size __n = __last - __first;
-    _Size __n_chunks = 0;
-    _Size __chunk_size = 0;
-    _Size __first_chunk_size = 0;
-    if (__n < __requested_chunk_size)
-    {
-        __chunk_size = __n;
-        __first_chunk_size = __n;
-        __n_chunks = 1;
-        return __chunk_metrics{__n_chunks, __chunk_size, __first_chunk_size};
-    }
-
-    __n_chunks = (__n / __requested_chunk_size) + 1;
-    __chunk_size = __n / __n_chunks;
-    __first_chunk_size = __chunk_size;
-    const _Size __n_leftover_items = __n - (__n_chunks * __chunk_size);
-
-    if (__n_leftover_items == __chunk_size)
-    {
-        __n_chunks += 1;
-        return __chunk_metrics{__n_chunks, __chunk_size, __first_chunk_size};
-    }
-    else if (__n_leftover_items == 0)
-    {
-        __first_chunk_size = __chunk_size;
-        return __chunk_metrics{__n_chunks, __chunk_size, __first_chunk_size};
-    }
-
-    const _Size __n_extra_items_per_chunk = __n_leftover_items / __n_chunks;
-    const _Size __n_final_leftover_items = __n_leftover_items - (__n_extra_items_per_chunk * __n_chunks);
-
-    __chunk_size += __n_extra_items_per_chunk;
-    __first_chunk_size = __chunk_size + __n_final_leftover_items;
-
-    return __chunk_metrics{__n_chunks, __chunk_size, __first_chunk_size};
-}
-
-template <typename _Iterator, typename _Index, typename _Func>
-void
-__process_chunk(const __chunk_metrics& __metrics, _Iterator __base, _Index __chunk_index, _Func __f)
-{
-    auto __this_chunk_size = __chunk_index == 0 ? __metrics.__first_chunk_size : __metrics.__chunk_size;
-    auto __index = __chunk_index == 0 ? 0
-                                      : (__chunk_index * __metrics.__chunk_size) +
-                                            (__metrics.__first_chunk_size - __metrics.__chunk_size);
-    auto __first = __base + __index;
-    auto __last = __first + __this_chunk_size;
-    __f(__first, __last);
-}
-
-} // namespace __omp_backend
-} // namespace __pstl
-
-#endif // _PSTL_INTERNAL_OMP_UTIL_H

diff  --git a/libcxx/include/__pstl/internal/parallel_backend.h b/libcxx/include/__pstl/internal/parallel_backend.h
deleted file mode 100644
index 9c30ee142746c3..00000000000000
--- a/libcxx/include/__pstl/internal/parallel_backend.h
+++ /dev/null
@@ -1,39 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_PARALLEL_BACKEND_H
-#define _PSTL_PARALLEL_BACKEND_H
-
-#include <__config>
-
-#if defined(_PSTL_PAR_BACKEND_SERIAL)
-#    include "parallel_backend_serial.h"
-#    if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-namespace __pstl
-{
-namespace __par_backend = __serial_backend;
-} // namespace __pstl
-#    endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-#elif defined(_PSTL_PAR_BACKEND_TBB)
-#    include "parallel_backend_tbb.h"
-namespace __pstl
-{
-namespace __par_backend = __tbb_backend;
-}
-#elif defined(_PSTL_PAR_BACKEND_OPENMP)
-#    include "parallel_backend_omp.h"
-namespace __pstl
-{
-namespace __par_backend = __omp_backend;
-}
-#else
-#  error "No backend set"
-#endif
-
-#endif /* _PSTL_PARALLEL_BACKEND_H */

diff  --git a/libcxx/include/__pstl/internal/parallel_backend_omp.h b/libcxx/include/__pstl/internal/parallel_backend_omp.h
deleted file mode 100644
index 7398cfe55929ae..00000000000000
--- a/libcxx/include/__pstl/internal/parallel_backend_omp.h
+++ /dev/null
@@ -1,58 +0,0 @@
-// -*- C++ -*-
-// -*-===----------------------------------------------------------------------===//
-//
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_PARALLEL_BACKEND_OMP_H
-#define _PSTL_PARALLEL_BACKEND_OMP_H
-
-//------------------------------------------------------------------------
-// parallel_invoke
-//------------------------------------------------------------------------
-
-#include "./omp/parallel_invoke.h"
-
-//------------------------------------------------------------------------
-// parallel_for
-//------------------------------------------------------------------------
-
-#include "./omp/parallel_for.h"
-
-//------------------------------------------------------------------------
-// parallel_for_each
-//------------------------------------------------------------------------
-
-#include "./omp/parallel_for_each.h"
-
-//------------------------------------------------------------------------
-// parallel_reduce
-//------------------------------------------------------------------------
-
-#include "./omp/parallel_reduce.h"
-#include "./omp/parallel_transform_reduce.h"
-
-//------------------------------------------------------------------------
-// parallel_scan
-//------------------------------------------------------------------------
-
-#include "./omp/parallel_scan.h"
-#include "./omp/parallel_transform_scan.h"
-
-//------------------------------------------------------------------------
-// parallel_stable_sort
-//------------------------------------------------------------------------
-
-#include "./omp/parallel_stable_partial_sort.h"
-#include "./omp/parallel_stable_sort.h"
-
-//------------------------------------------------------------------------
-// parallel_merge
-//------------------------------------------------------------------------
-#include "./omp/parallel_merge.h"
-
-#endif //_PSTL_PARALLEL_BACKEND_OMP_H

diff  --git a/libcxx/include/__pstl/internal/parallel_backend_serial.h b/libcxx/include/__pstl/internal/parallel_backend_serial.h
deleted file mode 100644
index dd72222f20ae6c..00000000000000
--- a/libcxx/include/__pstl/internal/parallel_backend_serial.h
+++ /dev/null
@@ -1,106 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_PARALLEL_BACKEND_SERIAL_H
-#define _PSTL_PARALLEL_BACKEND_SERIAL_H
-
-#include <__config>
-#include <__memory/allocator.h>
-#include <__pstl/internal/execution_impl.h>
-#include <__utility/forward.h>
-#include <cstddef>
-
-#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
-namespace __pstl
-{
-namespace __serial_backend
-{
-
-template <typename _Tp>
-class __buffer
-{
-    std::allocator<_Tp> __allocator_;
-    _Tp* __ptr_;
-    const std::size_t __buf_size_;
-    __buffer(const __buffer&) = delete;
-    void
-    operator=(const __buffer&) = delete;
-
-  public:
-    _LIBCPP_HIDE_FROM_ABI
-    __buffer(std::size_t __n) : __allocator_(), __ptr_(__allocator_.allocate(__n)), __buf_size_(__n) {}
-
-    _LIBCPP_HIDE_FROM_ABI operator bool() const { return __ptr_ != nullptr; }
-    _LIBCPP_HIDE_FROM_ABI _Tp*
-    get() const
-    {
-        return __ptr_;
-    }
-    _LIBCPP_HIDE_FROM_ABI ~__buffer() { __allocator_.deallocate(__ptr_, __buf_size_); }
-};
-
-template <class _ExecutionPolicy, class _Value, class _Index, typename _RealBody, typename _Reduction>
-_LIBCPP_HIDE_FROM_ABI _Value
-__parallel_reduce(__pstl::__internal::__serial_backend_tag, _ExecutionPolicy&&, _Index __first, _Index __last,
-                  const _Value& __identity, const _RealBody& __real_body, const _Reduction&)
-{
-    if (__first == __last)
-    {
-        return __identity;
-    }
-    else
-    {
-        return __real_body(__first, __last, __identity);
-    }
-}
-
-template <class _ExecutionPolicy, typename _Index, typename _Tp, typename _Rp, typename _Cp, typename _Sp, typename _Ap>
-_LIBCPP_HIDE_FROM_ABI void
-__parallel_strict_scan(__pstl::__internal::__serial_backend_tag, _ExecutionPolicy&&, _Index __n, _Tp __initial,
-                       _Rp __reduce, _Cp __combine, _Sp __scan, _Ap __apex)
-{
-    _Tp __sum = __initial;
-    if (__n)
-        __sum = __combine(__sum, __reduce(_Index(0), __n));
-    __apex(__sum);
-    if (__n)
-        __scan(_Index(0), __n, __initial);
-}
-
-template <class _ExecutionPolicy, class _Index, class _UnaryOp, class _Tp, class _BinaryOp, class _Reduce, class _Scan>
-_LIBCPP_HIDE_FROM_ABI _Tp
-__parallel_transform_scan(__pstl::__internal::__serial_backend_tag, _ExecutionPolicy&&, _Index __n, _UnaryOp,
-                          _Tp __init, _BinaryOp, _Reduce, _Scan __scan)
-{
-    return __scan(_Index(0), __n, __init);
-}
-
-template <class _ExecutionPolicy, typename _RandomAccessIterator, typename _Compare, typename _LeafSort>
-_LIBCPP_HIDE_FROM_ABI void
-__parallel_stable_sort(__pstl::__internal::__serial_backend_tag, _ExecutionPolicy&&, _RandomAccessIterator __first,
-                       _RandomAccessIterator __last, _Compare __comp, _LeafSort __leaf_sort, std::size_t = 0)
-{
-    __leaf_sort(__first, __last, __comp);
-}
-
-template <class _ExecutionPolicy, typename _F1, typename _F2>
-_LIBCPP_HIDE_FROM_ABI void
-__parallel_invoke(__pstl::__internal::__serial_backend_tag, _ExecutionPolicy&&, _F1&& __f1, _F2&& __f2)
-{
-    std::forward<_F1>(__f1)();
-    std::forward<_F2>(__f2)();
-}
-
-} // namespace __serial_backend
-} // namespace __pstl
-
-#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
-#endif /* _PSTL_PARALLEL_BACKEND_SERIAL_H */

diff  --git a/libcxx/include/__pstl/internal/parallel_backend_tbb.h b/libcxx/include/__pstl/internal/parallel_backend_tbb.h
deleted file mode 100644
index 6a9a05ddd61f56..00000000000000
--- a/libcxx/include/__pstl/internal/parallel_backend_tbb.h
+++ /dev/null
@@ -1,1295 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_PARALLEL_BACKEND_TBB_H
-#define _PSTL_PARALLEL_BACKEND_TBB_H
-
-#include <__assert>
-#include <__config>
-#include <algorithm>
-#include <type_traits>
-
-#include "parallel_backend_utils.h"
-
-// Bring in minimal required subset of Intel TBB
-#include <tbb/blocked_range.h>
-#include <tbb/parallel_for.h>
-#include <tbb/parallel_reduce.h>
-#include <tbb/parallel_scan.h>
-#include <tbb/parallel_invoke.h>
-#include <tbb/task_arena.h>
-#include <tbb/tbb_allocator.h>
-#include <tbb/task.h>
-
-#if TBB_INTERFACE_VERSION < 10000
-#    error Intel(R) Threading Building Blocks 2018 is required; older versions are not supported.
-#endif
-
-namespace __pstl
-{
-namespace __tbb_backend
-{
-
-//! Raw memory buffer with automatic freeing and no exceptions.
-/** Some of our algorithms need to start with raw memory buffer,
-not an initialize array, because initialization/destruction
-would make the span be at least O(N). */
-// tbb::allocator can improve performance in some cases.
-template <typename _Tp>
-class __buffer
-{
-    tbb::tbb_allocator<_Tp> _M_allocator;
-    _Tp* _M_ptr;
-    const std::size_t _M_buf_size;
-    __buffer(const __buffer&) = delete;
-    void
-    operator=(const __buffer&) = delete;
-
-  public:
-    //! Try to obtain buffer of given size to store objects of _Tp type
-    __buffer(std::size_t n) : _M_allocator(), _M_ptr(_M_allocator.allocate(n)), _M_buf_size(n) {}
-    //! True if buffer was successfully obtained, zero otherwise.
-    operator bool() const { return _M_ptr != NULL; }
-    //! Return pointer to buffer, or  NULL if buffer could not be obtained.
-    _Tp*
-    get() const
-    {
-        return _M_ptr;
-    }
-    //! Destroy buffer
-    ~__buffer() { _M_allocator.deallocate(_M_ptr, _M_buf_size); }
-};
-
-// Wrapper for tbb::task
-inline void
-__cancel_execution()
-{
-#if TBB_INTERFACE_VERSION <= 12000
-    tbb::task::self().group()->cancel_group_execution();
-#else
-    tbb::task::current_context()->cancel_group_execution();
-#endif
-}
-
-//------------------------------------------------------------------------
-// parallel_for
-//------------------------------------------------------------------------
-
-template <class _Index, class _RealBody>
-class __parallel_for_body
-{
-  public:
-    __parallel_for_body(const _RealBody& __body) : _M_body(__body) {}
-    __parallel_for_body(const __parallel_for_body& __body) : _M_body(__body._M_body) {}
-    void
-    operator()(const tbb::blocked_range<_Index>& __range) const
-    {
-        _M_body(__range.begin(), __range.end());
-    }
-
-  private:
-    _RealBody _M_body;
-};
-
-//! Evaluation of brick f[i,j) for each subrange [i,j) of [first,last)
-// wrapper over tbb::parallel_for
-template <class _ExecutionPolicy, class _Index, class _Fp>
-void
-__parallel_for(__pstl::__internal::__tbb_backend_tag, _ExecutionPolicy&&, _Index __first, _Index __last, _Fp __f)
-{
-    tbb::this_task_arena::isolate([=]() {
-        tbb::parallel_for(tbb::blocked_range<_Index>(__first, __last), __parallel_for_body<_Index, _Fp>(__f));
-    });
-}
-
-//! Evaluation of brick f[i,j) for each subrange [i,j) of [first,last)
-// wrapper over tbb::parallel_reduce
-template <class _ExecutionPolicy, class _Value, class _Index, typename _RealBody, typename _Reduction>
-_Value
-__parallel_reduce(__pstl::__internal::__tbb_backend_tag, _ExecutionPolicy&&, _Index __first, _Index __last,
-                  const _Value& __identity, const _RealBody& __real_body, const _Reduction& __reduction)
-{
-    return tbb::this_task_arena::isolate([__first, __last, &__identity, &__real_body, &__reduction]() -> _Value {
-        return tbb::parallel_reduce(
-            tbb::blocked_range<_Index>(__first, __last), __identity,
-            [__real_body](const tbb::blocked_range<_Index>& __r, const _Value& __value) -> _Value {
-                return __real_body(__r.begin(), __r.end(), __value);
-            },
-            __reduction);
-    });
-}
-
-//------------------------------------------------------------------------
-// parallel_transform_reduce
-//
-// Notation:
-//      r(i,j,init) returns reduction of init with reduction over [i,j)
-//      u(i) returns f(i,i+1,identity) for a hypothetical left identity element of r
-//      c(x,y) combines values x and y that were the result of r or u
-//------------------------------------------------------------------------
-
-template <class _Index, class _Up, class _Tp, class _Cp, class _Rp>
-struct __par_trans_red_body
-{
-    alignas(_Tp) char _M_sum_storage[sizeof(_Tp)]; // Holds generalized non-commutative sum when has_sum==true
-    _Rp _M_brick_reduce;                           // Most likely to have non-empty layout
-    _Up _M_u;
-    _Cp _M_combine;
-    bool _M_has_sum; // Put last to minimize size of class
-    _Tp&
-    sum()
-    {
-        __TBB_ASSERT(_M_has_sum, "sum expected");
-        return *(_Tp*)_M_sum_storage;
-    }
-    __par_trans_red_body(_Up __u, _Tp __init, _Cp __c, _Rp __r)
-        : _M_brick_reduce(__r), _M_u(__u), _M_combine(__c), _M_has_sum(true)
-    {
-        new (_M_sum_storage) _Tp(__init);
-    }
-
-    __par_trans_red_body(__par_trans_red_body& __left, tbb::split)
-        : _M_brick_reduce(__left._M_brick_reduce), _M_u(__left._M_u), _M_combine(__left._M_combine), _M_has_sum(false)
-    {
-    }
-
-    ~__par_trans_red_body()
-    {
-        // 17.6.5.12 tells us to not worry about catching exceptions from destructors.
-        if (_M_has_sum)
-            sum().~_Tp();
-    }
-
-    void
-    join(__par_trans_red_body& __rhs)
-    {
-        sum() = _M_combine(sum(), __rhs.sum());
-    }
-
-    void
-    operator()(const tbb::blocked_range<_Index>& __range)
-    {
-        _Index __i = __range.begin();
-        _Index __j = __range.end();
-        if (!_M_has_sum)
-        {
-            __TBB_ASSERT(__range.size() > 1, "there should be at least 2 elements");
-            new (&_M_sum_storage)
-                _Tp(_M_combine(_M_u(__i), _M_u(__i + 1))); // The condition i+1 < j is provided by the grain size of 3
-            _M_has_sum = true;
-            std::advance(__i, 2);
-            if (__i == __j)
-                return;
-        }
-        sum() = _M_brick_reduce(__i, __j, sum());
-    }
-};
-
-template <class _ExecutionPolicy, class _Index, class _Up, class _Tp, class _Cp, class _Rp>
-_Tp
-__parallel_transform_reduce(__pstl::__internal::__tbb_backend_tag, _ExecutionPolicy&&, _Index __first, _Index __last,
-                            _Up __u, _Tp __init, _Cp __combine, _Rp __brick_reduce)
-{
-    __tbb_backend::__par_trans_red_body<_Index, _Up, _Tp, _Cp, _Rp> __body(__u, __init, __combine, __brick_reduce);
-    // The grain size of 3 is used in order to provide mininum 2 elements for each body
-    tbb::this_task_arena::isolate(
-        [__first, __last, &__body]() { tbb::parallel_reduce(tbb::blocked_range<_Index>(__first, __last, 3), __body); });
-    return __body.sum();
-}
-
-//------------------------------------------------------------------------
-// parallel_scan
-//------------------------------------------------------------------------
-
-template <class _Index, class _Up, class _Tp, class _Cp, class _Rp, class _Sp>
-class __trans_scan_body
-{
-    alignas(_Tp) char _M_sum_storage[sizeof(_Tp)]; // Holds generalized non-commutative sum when has_sum==true
-    _Rp _M_brick_reduce;                           // Most likely to have non-empty layout
-    _Up _M_u;
-    _Cp _M_combine;
-    _Sp _M_scan;
-    bool _M_has_sum; // Put last to minimize size of class
-  public:
-    __trans_scan_body(_Up __u, _Tp __init, _Cp __combine, _Rp __reduce, _Sp __scan)
-        : _M_brick_reduce(__reduce), _M_u(__u), _M_combine(__combine), _M_scan(__scan), _M_has_sum(true)
-    {
-        new (_M_sum_storage) _Tp(__init);
-    }
-
-    __trans_scan_body(__trans_scan_body& __b, tbb::split)
-        : _M_brick_reduce(__b._M_brick_reduce), _M_u(__b._M_u), _M_combine(__b._M_combine), _M_scan(__b._M_scan),
-          _M_has_sum(false)
-    {
-    }
-
-    ~__trans_scan_body()
-    {
-        // 17.6.5.12 tells us to not worry about catching exceptions from destructors.
-        if (_M_has_sum)
-            sum().~_Tp();
-    }
-
-    _Tp&
-    sum() const
-    {
-        __TBB_ASSERT(_M_has_sum, "sum expected");
-        return *const_cast<_Tp*>(reinterpret_cast<_Tp const*>(_M_sum_storage));
-    }
-
-    void
-    operator()(const tbb::blocked_range<_Index>& __range, tbb::pre_scan_tag)
-    {
-        _Index __i = __range.begin();
-        _Index __j = __range.end();
-        if (!_M_has_sum)
-        {
-            new (&_M_sum_storage) _Tp(_M_u(__i));
-            _M_has_sum = true;
-            ++__i;
-            if (__i == __j)
-                return;
-        }
-        sum() = _M_brick_reduce(__i, __j, sum());
-    }
-
-    void
-    operator()(const tbb::blocked_range<_Index>& __range, tbb::final_scan_tag)
-    {
-        sum() = _M_scan(__range.begin(), __range.end(), sum());
-    }
-
-    void
-    reverse_join(__trans_scan_body& __a)
-    {
-        if (_M_has_sum)
-        {
-            sum() = _M_combine(__a.sum(), sum());
-        }
-        else
-        {
-            new (&_M_sum_storage) _Tp(__a.sum());
-            _M_has_sum = true;
-        }
-    }
-
-    void
-    assign(__trans_scan_body& __b)
-    {
-        sum() = __b.sum();
-    }
-};
-
-template <typename _Index>
-_Index
-__split(_Index __m)
-{
-    _Index __k = 1;
-    while (2 * __k < __m)
-        __k *= 2;
-    return __k;
-}
-
-//------------------------------------------------------------------------
-// __parallel_strict_scan
-//------------------------------------------------------------------------
-
-template <typename _Index, typename _Tp, typename _Rp, typename _Cp>
-void
-__upsweep(_Index __i, _Index __m, _Index __tilesize, _Tp* __r, _Index __lastsize, _Rp __reduce, _Cp __combine)
-{
-    if (__m == 1)
-        __r[0] = __reduce(__i * __tilesize, __lastsize);
-    else
-    {
-        _Index __k = __split(__m);
-        tbb::parallel_invoke(
-            [=] { __tbb_backend::__upsweep(__i, __k, __tilesize, __r, __tilesize, __reduce, __combine); },
-            [=] {
-                __tbb_backend::__upsweep(__i + __k, __m - __k, __tilesize, __r + __k, __lastsize, __reduce, __combine);
-            });
-        if (__m == 2 * __k)
-            __r[__m - 1] = __combine(__r[__k - 1], __r[__m - 1]);
-    }
-}
-
-template <typename _Index, typename _Tp, typename _Cp, typename _Sp>
-void
-__downsweep(_Index __i, _Index __m, _Index __tilesize, _Tp* __r, _Index __lastsize, _Tp __initial, _Cp __combine,
-            _Sp __scan)
-{
-    if (__m == 1)
-        __scan(__i * __tilesize, __lastsize, __initial);
-    else
-    {
-        const _Index __k = __split(__m);
-        tbb::parallel_invoke(
-            [=] { __tbb_backend::__downsweep(__i, __k, __tilesize, __r, __tilesize, __initial, __combine, __scan); },
-            // Assumes that __combine never throws.
-            //TODO: Consider adding a requirement for user functors to be constant.
-            [=, &__combine] {
-                __tbb_backend::__downsweep(__i + __k, __m - __k, __tilesize, __r + __k, __lastsize,
-                                           __combine(__initial, __r[__k - 1]), __combine, __scan);
-            });
-    }
-}
-
-// Adapted from Intel(R) Cilk(TM) version from cilkpub.
-// Let i:len denote a counted interval of length n starting at i.  s denotes a generalized-sum value.
-// Expected actions of the functors are:
-//     reduce(i,len) -> s  -- return reduction value of i:len.
-//     combine(s1,s2) -> s -- return merged sum
-//     apex(s) -- do any processing necessary between reduce and scan.
-//     scan(i,len,initial) -- perform scan over i:len starting with initial.
-// The initial range 0:n is partitioned into consecutive subranges.
-// reduce and scan are each called exactly once per subrange.
-// Thus callers can rely upon side effects in reduce.
-// combine must not throw an exception.
-// apex is called exactly once, after all calls to reduce and before all calls to scan.
-// For example, it's useful for allocating a __buffer used by scan but whose size is the sum of all reduction values.
-// T must have a trivial constructor and destructor.
-template <class _ExecutionPolicy, typename _Index, typename _Tp, typename _Rp, typename _Cp, typename _Sp, typename _Ap>
-void
-__parallel_strict_scan(__pstl::__internal::__tbb_backend_tag, _ExecutionPolicy&&, _Index __n, _Tp __initial,
-                       _Rp __reduce, _Cp __combine, _Sp __scan, _Ap __apex)
-{
-    tbb::this_task_arena::isolate([=, &__combine]() {
-        if (__n > 1)
-        {
-            _Index __p = tbb::this_task_arena::max_concurrency();
-            const _Index __slack = 4;
-            _Index __tilesize = (__n - 1) / (__slack * __p) + 1;
-            _Index __m = (__n - 1) / __tilesize;
-            __buffer<_Tp> __buf(__m + 1);
-            _Tp* __r = __buf.get();
-            __tbb_backend::__upsweep(_Index(0), _Index(__m + 1), __tilesize, __r, __n - __m * __tilesize, __reduce,
-                                     __combine);
-
-            // When __apex is a no-op and __combine has no side effects, a good optimizer
-            // should be able to eliminate all code between here and __apex.
-            // Alternatively, provide a default value for __apex that can be
-            // recognized by metaprogramming that conditionlly executes the following.
-            size_t __k = __m + 1;
-            _Tp __t = __r[__k - 1];
-            while ((__k &= __k - 1))
-                __t = __combine(__r[__k - 1], __t);
-            __apex(__combine(__initial, __t));
-            __tbb_backend::__downsweep(_Index(0), _Index(__m + 1), __tilesize, __r, __n - __m * __tilesize, __initial,
-                                       __combine, __scan);
-            return;
-        }
-        // Fewer than 2 elements in sequence, or out of memory.  Handle has single block.
-        _Tp __sum = __initial;
-        if (__n)
-            __sum = __combine(__sum, __reduce(_Index(0), __n));
-        __apex(__sum);
-        if (__n)
-            __scan(_Index(0), __n, __initial);
-    });
-}
-
-template <class _ExecutionPolicy, class _Index, class _Up, class _Tp, class _Cp, class _Rp, class _Sp>
-_Tp
-__parallel_transform_scan(__pstl::__internal::__tbb_backend_tag, _ExecutionPolicy&&, _Index __n, _Up __u, _Tp __init,
-                          _Cp __combine, _Rp __brick_reduce, _Sp __scan)
-{
-    __trans_scan_body<_Index, _Up, _Tp, _Cp, _Rp, _Sp> __body(__u, __init, __combine, __brick_reduce, __scan);
-    auto __range = tbb::blocked_range<_Index>(0, __n);
-    tbb::this_task_arena::isolate([__range, &__body]() { tbb::parallel_scan(__range, __body); });
-    return __body.sum();
-}
-
-//------------------------------------------------------------------------
-// parallel_stable_sort
-//------------------------------------------------------------------------
-
-//------------------------------------------------------------------------
-// stable_sort utilities
-//
-// These are used by parallel implementations but do not depend on them.
-//------------------------------------------------------------------------
-#define _PSTL_MERGE_CUT_OFF 2000
-
-template <typename _Func>
-class __func_task;
-template <typename _Func>
-class __root_task;
-
-#if TBB_INTERFACE_VERSION <= 12000
-class __task : public tbb::task
-{
-  public:
-    template <typename _Fn>
-    __task*
-    make_continuation(_Fn&& __f)
-    {
-        return new (allocate_continuation()) __func_task<typename std::decay<_Fn>::type>(std::forward<_Fn>(__f));
-    }
-
-    template <typename _Fn>
-    __task*
-    make_child_of(__task* parent, _Fn&& __f)
-    {
-        return new (parent->allocate_child()) __func_task<typename std::decay<_Fn>::type>(std::forward<_Fn>(__f));
-    }
-
-    template <typename _Fn>
-    __task*
-    make_additional_child_of(tbb::task* parent, _Fn&& __f)
-    {
-        return new (tbb::task::allocate_additional_child_of(*parent))
-            __func_task<typename std::decay<_Fn>::type>(std::forward<_Fn>(__f));
-    }
-
-    inline void
-    recycle_as_continuation()
-    {
-        tbb::task::recycle_as_continuation();
-    }
-
-    inline void
-    recycle_as_child_of(__task* parent)
-    {
-        tbb::task::recycle_as_child_of(*parent);
-    }
-
-    inline void
-    spawn(__task* __t)
-    {
-        tbb::task::spawn(*__t);
-    }
-
-    template <typename _Fn>
-    static inline void
-    spawn_root_and_wait(__root_task<_Fn>& __root)
-    {
-        tbb::task::spawn_root_and_wait(*__root._M_task);
-    }
-};
-
-template <typename _Func>
-class __func_task : public __task
-{
-    _Func _M_func;
-
-    tbb::task*
-    execute()
-    {
-        return _M_func(this);
-    };
-
-  public:
-    template <typename _Fn>
-    __func_task(_Fn&& __f) : _M_func{std::forward<_Fn>(__f)}
-    {
-    }
-
-    _Func&
-    body()
-    {
-        return _M_func;
-    }
-};
-
-template <typename _Func>
-class __root_task
-{
-    tbb::task* _M_task;
-
-  public:
-    template <typename... Args>
-    __root_task(Args&&... args)
-        : _M_task{new (tbb::task::allocate_root()) __func_task<_Func>{_Func(std::forward<Args>(args)...)}}
-    {
-    }
-
-    friend class __task;
-    friend class __func_task<_Func>;
-};
-
-#else  // TBB_INTERFACE_VERSION <= 12000
-class __task : public tbb::detail::d1::task
-{
-  protected:
-    tbb::detail::d1::small_object_allocator _M_allocator{};
-    tbb::detail::d1::execution_data* _M_execute_data{};
-    __task* _M_parent{};
-    std::atomic<int> _M_refcount{};
-    bool _M_recycle{};
-
-    template <typename _Fn>
-    __task*
-    allocate_func_task(_Fn&& __f)
-    {
-        _LIBCPP_ASSERT_UNCATEGORIZED(_M_execute_data != nullptr, "");
-        tbb::detail::d1::small_object_allocator __alloc{};
-        auto __t =
-            __alloc.new_object<__func_task<typename std::decay<_Fn>::type>>(*_M_execute_data, std::forward<_Fn>(__f));
-        __t->_M_allocator = __alloc;
-        return __t;
-    }
-
-  public:
-    __task*
-    parent()
-    {
-        return _M_parent;
-    }
-
-    void
-    set_ref_count(int __n)
-    {
-        _M_refcount.store(__n, std::memory_order_release);
-    }
-
-    template <typename _Fn>
-    __task*
-    make_continuation(_Fn&& __f)
-    {
-        auto __t = allocate_func_task(std::forward<_Fn&&>(__f));
-        __t->_M_parent = _M_parent;
-        _M_parent = nullptr;
-        return __t;
-    }
-
-    template <typename _Fn>
-    __task*
-    make_child_of(__task* __parent, _Fn&& __f)
-    {
-        auto __t = allocate_func_task(std::forward<_Fn&&>(__f));
-        __t->_M_parent = __parent;
-        return __t;
-    }
-
-    template <typename _Fn>
-    __task*
-    make_additional_child_of(__task* __parent, _Fn&& __f)
-    {
-        auto __t = make_child_of(__parent, std::forward<_Fn>(__f));
-        _LIBCPP_ASSERT_UNCATEGORIZED(__parent->_M_refcount.load(std::memory_order_relaxed) > 0, "");
-        ++__parent->_M_refcount;
-        return __t;
-    }
-
-    inline void
-    recycle_as_continuation()
-    {
-        _M_recycle = true;
-    }
-
-    inline void
-    recycle_as_child_of(__task* parent)
-    {
-        _M_recycle = true;
-        _M_parent = parent;
-    }
-
-    inline void
-    spawn(__task* __t)
-    {
-        _LIBCPP_ASSERT_UNCATEGORIZED(_M_execute_data != nullptr, "");
-        tbb::detail::d1::spawn(*__t, *_M_execute_data->context);
-    }
-
-    template <typename _Fn>
-    static inline void
-    spawn_root_and_wait(__root_task<_Fn>& __root)
-    {
-        tbb::detail::d1::execute_and_wait(*__root._M_func_task, __root._M_context, __root._M_wait_object,
-                                          __root._M_context);
-    }
-
-    template <typename _Func>
-    friend class __func_task;
-};
-
-template <typename _Func>
-class __func_task : public __task
-{
-    _Func _M_func;
-
-    __task*
-    execute(tbb::detail::d1::execution_data& __ed) override
-    {
-        _M_execute_data = &__ed;
-        _M_recycle = false;
-        __task* __next = _M_func(this);
-        return finalize(__next);
-    };
-
-    __task*
-    cancel(tbb::detail::d1::execution_data& __ed) override
-    {
-        return finalize(nullptr);
-    }
-
-    __task*
-    finalize(__task* __next)
-    {
-        bool __recycle = _M_recycle;
-        _M_recycle = false;
-
-        if (__recycle)
-        {
-            return __next;
-        }
-
-        auto __parent = _M_parent;
-        auto __alloc = _M_allocator;
-        auto __ed = _M_execute_data;
-
-        this->~__func_task();
-
-        _LIBCPP_ASSERT_UNCATEGORIZED(__parent != nullptr, "");
-        _LIBCPP_ASSERT_UNCATEGORIZED(__parent->_M_refcount.load(std::memory_order_relaxed) > 0, "");
-        if (--__parent->_M_refcount == 0)
-        {
-            _LIBCPP_ASSERT_UNCATEGORIZED(__next == nullptr, "");
-            __alloc.deallocate(this, *__ed);
-            return __parent;
-        }
-
-        return __next;
-    }
-
-    friend class __root_task<_Func>;
-
-  public:
-    template <typename _Fn>
-    __func_task(_Fn&& __f) : _M_func(std::forward<_Fn>(__f))
-    {
-    }
-
-    _Func&
-    body()
-    {
-        return _M_func;
-    }
-};
-
-template <typename _Func>
-class __root_task : public __task
-{
-    __task*
-    execute(tbb::detail::d1::execution_data& __ed) override
-    {
-        _M_wait_object.release();
-        return nullptr;
-    };
-
-    __task*
-    cancel(tbb::detail::d1::execution_data& __ed) override
-    {
-        _M_wait_object.release();
-        return nullptr;
-    }
-
-    __func_task<_Func>* _M_func_task{};
-    tbb::detail::d1::wait_context _M_wait_object{0};
-    tbb::task_group_context _M_context{};
-
-  public:
-    template <typename... Args>
-    __root_task(Args&&... args) : _M_wait_object{1}
-    {
-        tbb::detail::d1::small_object_allocator __alloc{};
-        _M_func_task = __alloc.new_object<__func_task<_Func>>(_Func(std::forward<Args>(args)...));
-        _M_func_task->_M_allocator = __alloc;
-        _M_func_task->_M_parent = this;
-        _M_refcount.store(1, std::memory_order_relaxed);
-    }
-
-    friend class __task;
-};
-#endif // TBB_INTERFACE_VERSION <= 12000
-
-template <typename _RandomAccessIterator1, typename _RandomAccessIterator2, typename _Compare, typename _Cleanup,
-          typename _LeafMerge>
-class __merge_func
-{
-    typedef typename std::iterator_traits<_RandomAccessIterator1>::
diff erence_type _DifferenceType1;
-    typedef typename std::iterator_traits<_RandomAccessIterator2>::
diff erence_type _DifferenceType2;
-    typedef typename std::common_type<_DifferenceType1, _DifferenceType2>::type _SizeType;
-    typedef typename std::iterator_traits<_RandomAccessIterator1>::value_type _ValueType;
-
-    _RandomAccessIterator1 _M_x_beg;
-    _RandomAccessIterator2 _M_z_beg;
-
-    _SizeType _M_xs, _M_xe;
-    _SizeType _M_ys, _M_ye;
-    _SizeType _M_zs;
-    _Compare _M_comp;
-    _LeafMerge _M_leaf_merge;
-    _SizeType _M_nsort; //number of elements to be sorted for partial_sort alforithm
-
-    static const _SizeType __merge_cut_off = _PSTL_MERGE_CUT_OFF;
-
-    bool _root;   //means a task is merging root task
-    bool _x_orig; //"true" means X(or left ) subrange is in the original container; false - in the buffer
-    bool _y_orig; //"true" means Y(or right) subrange is in the original container; false - in the buffer
-    bool _split; //"true" means a merge task is a split task for parallel merging, the execution logic 
diff ers
-
-    bool
-    is_partial() const
-    {
-        return _M_nsort > 0;
-    }
-
-    struct __move_value
-    {
-        template <typename Iterator1, typename Iterator2>
-        void
-        operator()(Iterator1 __x, Iterator2 __z)
-        {
-            *__z = std::move(*__x);
-        }
-    };
-
-    struct __move_value_construct
-    {
-        template <typename Iterator1, typename Iterator2>
-        void
-        operator()(Iterator1 __x, Iterator2 __z)
-        {
-            ::new (std::addressof(*__z)) _ValueType(std::move(*__x));
-        }
-    };
-
-    struct __move_range
-    {
-        template <typename Iterator1, typename Iterator2>
-        Iterator2
-        operator()(Iterator1 __first1, Iterator1 __last1, Iterator2 __first2)
-        {
-            if (__last1 - __first1 < __merge_cut_off)
-                return std::move(__first1, __last1, __first2);
-
-            auto __n = __last1 - __first1;
-            tbb::parallel_for(tbb::blocked_range<_SizeType>(0, __n, __merge_cut_off),
-                              [__first1, __first2](const tbb::blocked_range<_SizeType>& __range) {
-                                  std::move(__first1 + __range.begin(), __first1 + __range.end(),
-                                            __first2 + __range.begin());
-                              });
-            return __first2 + __n;
-        }
-    };
-
-    struct __move_range_construct
-    {
-        template <typename Iterator1, typename Iterator2>
-        Iterator2
-        operator()(Iterator1 __first1, Iterator1 __last1, Iterator2 __first2)
-        {
-            if (__last1 - __first1 < __merge_cut_off)
-            {
-                for (; __first1 != __last1; ++__first1, ++__first2)
-                    __move_value_construct()(__first1, __first2);
-                return __first2;
-            }
-
-            auto __n = __last1 - __first1;
-            tbb::parallel_for(tbb::blocked_range<_SizeType>(0, __n, __merge_cut_off),
-                              [__first1, __first2](const tbb::blocked_range<_SizeType>& __range) {
-                                  for (auto i = __range.begin(); i != __range.end(); ++i)
-                                      __move_value_construct()(__first1 + i, __first2 + i);
-                              });
-            return __first2 + __n;
-        }
-    };
-
-    struct __cleanup_range
-    {
-        template <typename Iterator>
-        void
-        operator()(Iterator __first, Iterator __last)
-        {
-            if (__last - __first < __merge_cut_off)
-                _Cleanup()(__first, __last);
-            else
-            {
-                auto __n = __last - __first;
-                tbb::parallel_for(tbb::blocked_range<_SizeType>(0, __n, __merge_cut_off),
-                                  [__first](const tbb::blocked_range<_SizeType>& __range) {
-                                      _Cleanup()(__first + __range.begin(), __first + __range.end());
-                                  });
-            }
-        }
-    };
-
-  public:
-    __merge_func(_SizeType __xs, _SizeType __xe, _SizeType __ys, _SizeType __ye, _SizeType __zs, _Compare __comp,
-                 _Cleanup, _LeafMerge __leaf_merge, _SizeType __nsort, _RandomAccessIterator1 __x_beg,
-                 _RandomAccessIterator2 __z_beg, bool __x_orig, bool __y_orig, bool __root)
-        : _M_xs(__xs), _M_xe(__xe), _M_ys(__ys), _M_ye(__ye), _M_zs(__zs), _M_x_beg(__x_beg), _M_z_beg(__z_beg),
-          _M_comp(__comp), _M_leaf_merge(__leaf_merge), _M_nsort(__nsort), _root(__root),
-          _x_orig(__x_orig), _y_orig(__y_orig), _split(false)
-    {
-    }
-
-    bool
-    is_left(_SizeType __idx) const
-    {
-        return _M_xs == __idx;
-    }
-
-    template <typename IndexType>
-    void
-    set_odd(IndexType __idx, bool __on_off)
-    {
-        if (is_left(__idx))
-            _x_orig = __on_off;
-        else
-            _y_orig = __on_off;
-    }
-
-    __task*
-    operator()(__task* __self);
-
-  private:
-    __merge_func*
-    parent_merge(__task* __self) const
-    {
-        return _root ? nullptr : &static_cast<__func_task<__merge_func>*>(__self->parent())->body();
-    }
-    bool
-    x_less_y()
-    {
-        const auto __nx = (_M_xe - _M_xs);
-        const auto __ny = (_M_ye - _M_ys);
-        _LIBCPP_ASSERT_UNCATEGORIZED(__nx > 0 && __ny > 0, "");
-
-        _LIBCPP_ASSERT_UNCATEGORIZED(_x_orig == _y_orig, "");
-        _LIBCPP_ASSERT_UNCATEGORIZED(!is_partial(), "");
-
-        if (_x_orig)
-        {
-            _LIBCPP_ASSERT_UNCATEGORIZED(std::is_sorted(_M_x_beg + _M_xs, _M_x_beg + _M_xe, _M_comp), "");
-            _LIBCPP_ASSERT_UNCATEGORIZED(std::is_sorted(_M_x_beg + _M_ys, _M_x_beg + _M_ye, _M_comp), "");
-            return !_M_comp(*(_M_x_beg + _M_ys), *(_M_x_beg + _M_xe - 1));
-        }
-
-        _LIBCPP_ASSERT_UNCATEGORIZED(std::is_sorted(_M_z_beg + _M_xs, _M_z_beg + _M_xe, _M_comp), "");
-        _LIBCPP_ASSERT_UNCATEGORIZED(std::is_sorted(_M_z_beg + _M_ys, _M_z_beg + _M_ye, _M_comp), "");
-        return !_M_comp(*(_M_z_beg + _M_zs + __nx), *(_M_z_beg + _M_zs + __nx - 1));
-    }
-    void
-    move_x_range()
-    {
-        const auto __nx = (_M_xe - _M_xs);
-        const auto __ny = (_M_ye - _M_ys);
-        _LIBCPP_ASSERT_UNCATEGORIZED(__nx > 0 && __ny > 0, "");
-
-        if (_x_orig)
-            __move_range_construct()(_M_x_beg + _M_xs, _M_x_beg + _M_xe, _M_z_beg + _M_zs);
-        else
-        {
-            __move_range()(_M_z_beg + _M_zs, _M_z_beg + _M_zs + __nx, _M_x_beg + _M_xs);
-            __cleanup_range()(_M_z_beg + _M_zs, _M_z_beg + _M_zs + __nx);
-        }
-
-        _x_orig = !_x_orig;
-    }
-    void
-    move_y_range()
-    {
-        const auto __nx = (_M_xe - _M_xs);
-        const auto __ny = (_M_ye - _M_ys);
-
-        if (_y_orig)
-            __move_range_construct()(_M_x_beg + _M_ys, _M_x_beg + _M_ye, _M_z_beg + _M_zs + __nx);
-        else
-        {
-            __move_range()(_M_z_beg + _M_zs + __nx, _M_z_beg + _M_zs + __nx + __ny, _M_x_beg + _M_ys);
-            __cleanup_range()(_M_z_beg + _M_zs + __nx, _M_z_beg + _M_zs + __nx + __ny);
-        }
-
-        _y_orig = !_y_orig;
-    }
-    __task*
-    merge_ranges(__task* __self)
-    {
-        _LIBCPP_ASSERT_UNCATEGORIZED(_x_orig == _y_orig, ""); // two merged subrange must be lie into the same buffer
-
-        const auto __nx = (_M_xe - _M_xs);
-        const auto __ny = (_M_ye - _M_ys);
-        const auto __n = __nx + __ny;
-
-        // need to merge {x} and {y}
-        if (__n > __merge_cut_off)
-            return split_merging(__self);
-
-        //merge to buffer
-        if (_x_orig)
-        {
-            _M_leaf_merge(_M_x_beg + _M_xs, _M_x_beg + _M_xe, _M_x_beg + _M_ys, _M_x_beg + _M_ye, _M_z_beg + _M_zs,
-                          _M_comp, __move_value_construct(), __move_value_construct(), __move_range_construct(),
-                          __move_range_construct());
-            _LIBCPP_ASSERT_UNCATEGORIZED(parent_merge(__self), ""); //not root merging task
-        }
-        //merge to "origin"
-        else
-        {
-            _LIBCPP_ASSERT_UNCATEGORIZED(_x_orig == _y_orig, "");
-
-            _LIBCPP_ASSERT_UNCATEGORIZED(
-                is_partial() || std::is_sorted(_M_z_beg + _M_xs, _M_z_beg + _M_xe, _M_comp), "");
-            _LIBCPP_ASSERT_UNCATEGORIZED(
-                is_partial() || std::is_sorted(_M_z_beg + _M_ys, _M_z_beg + _M_ye, _M_comp), "");
-
-            const auto __nx = (_M_xe - _M_xs);
-            const auto __ny = (_M_ye - _M_ys);
-
-            _M_leaf_merge(_M_z_beg + _M_xs, _M_z_beg + _M_xe, _M_z_beg + _M_ys, _M_z_beg + _M_ye, _M_x_beg + _M_zs,
-                          _M_comp, __move_value(), __move_value(), __move_range(), __move_range());
-
-            __cleanup_range()(_M_z_beg + _M_xs, _M_z_beg + _M_xe);
-            __cleanup_range()(_M_z_beg + _M_ys, _M_z_beg + _M_ye);
-        }
-        return nullptr;
-    }
-
-    __task*
-    process_ranges(__task* __self)
-    {
-        _LIBCPP_ASSERT_UNCATEGORIZED(_x_orig == _y_orig, "");
-        _LIBCPP_ASSERT_UNCATEGORIZED(!_split, "");
-
-        auto p = parent_merge(__self);
-
-        if (!p)
-        { //root merging task
-
-            //optimization, just for sort algorithm, //{x} <= {y}
-            if (!is_partial() && x_less_y()) //we have a solution
-            {
-                if (!_x_orig)
-                {                   //we have to move the solution to the origin
-                    move_x_range(); //parallel moving
-                    move_y_range(); //parallel moving
-                }
-                return nullptr;
-            }
-            //else: if we have data in the origin,
-            //we have to move data to the buffer for final merging into the origin.
-            if (_x_orig)
-            {
-                move_x_range(); //parallel moving
-                move_y_range(); //parallel moving
-            }
-            // need to merge {x} and {y}.
-            return merge_ranges(__self);
-        }
-        //else: not root merging task (parent_merge() == NULL)
-        //optimization, just for sort algorithm, //{x} <= {y}
-        if (!is_partial() && x_less_y())
-        {
-            const auto id_range = _M_zs;
-            p->set_odd(id_range, _x_orig);
-            return nullptr;
-        }
-        //else: we have to revert "_x(y)_orig" flag of the parent merging task
-        const auto id_range = _M_zs;
-        p->set_odd(id_range, !_x_orig);
-
-        return merge_ranges(__self);
-    }
-
-    //splitting as merge task into 2 of the same level
-    __task*
-    split_merging(__task* __self)
-    {
-        _LIBCPP_ASSERT_UNCATEGORIZED(_x_orig == _y_orig, "");
-        const auto __nx = (_M_xe - _M_xs);
-        const auto __ny = (_M_ye - _M_ys);
-
-        _SizeType __xm{};
-        _SizeType __ym{};
-        if (__nx < __ny)
-        {
-            __ym = _M_ys + __ny / 2;
-
-            if (_x_orig)
-                __xm = std::upper_bound(_M_x_beg + _M_xs, _M_x_beg + _M_xe, *(_M_x_beg + __ym), _M_comp) - _M_x_beg;
-            else
-                __xm = std::upper_bound(_M_z_beg + _M_xs, _M_z_beg + _M_xe, *(_M_z_beg + __ym), _M_comp) - _M_z_beg;
-        }
-        else
-        {
-            __xm = _M_xs + __nx / 2;
-
-            if (_y_orig)
-                __ym = std::lower_bound(_M_x_beg + _M_ys, _M_x_beg + _M_ye, *(_M_x_beg + __xm), _M_comp) - _M_x_beg;
-            else
-                __ym = std::lower_bound(_M_z_beg + _M_ys, _M_z_beg + _M_ye, *(_M_z_beg + __xm), _M_comp) - _M_z_beg;
-        }
-
-        auto __zm = _M_zs + ((__xm - _M_xs) + (__ym - _M_ys));
-        __merge_func __right_func(__xm, _M_xe, __ym, _M_ye, __zm, _M_comp, _Cleanup(), _M_leaf_merge, _M_nsort,
-                                  _M_x_beg, _M_z_beg, _x_orig, _y_orig, _root);
-        __right_func._split = true;
-        auto __merge_task = __self->make_additional_child_of(__self->parent(), std::move(__right_func));
-        __self->spawn(__merge_task);
-        __self->recycle_as_continuation();
-
-        _M_xe = __xm;
-        _M_ye = __ym;
-        _split = true;
-
-        return __self;
-    }
-};
-
-template <typename _RandomAccessIterator1, typename _RandomAccessIterator2, typename __M_Compare, typename _Cleanup,
-          typename _LeafMerge>
-__task*
-__merge_func<_RandomAccessIterator1, _RandomAccessIterator2, __M_Compare, _Cleanup, _LeafMerge>::
-operator()(__task* __self)
-{
-    //a. split merge task into 2 of the same level; the special logic,
-    //without processing(process_ranges) adjacent sub-ranges x and y
-    if (_split)
-        return merge_ranges(__self);
-
-    //b. General merging of adjacent sub-ranges x and y (with optimization in case of {x} <= {y} )
-
-    //1. x and y are in the even buffer
-    //2. x and y are in the odd buffer
-    if (_x_orig == _y_orig)
-        return process_ranges(__self);
-
-    //3. x is in even buffer, y is in the odd buffer
-    //4. x is in odd buffer, y is in the even buffer
-    if (!parent_merge(__self))
-    { //root merge task
-        if (_x_orig)
-            move_x_range();
-        else
-            move_y_range();
-    }
-    else
-    {
-        const _SizeType __nx = (_M_xe - _M_xs);
-        const _SizeType __ny = (_M_ye - _M_ys);
-        _LIBCPP_ASSERT_UNCATEGORIZED(__nx > 0, "");
-        _LIBCPP_ASSERT_UNCATEGORIZED(__nx > 0, "");
-
-        if (__nx < __ny)
-            move_x_range();
-        else
-            move_y_range();
-    }
-
-    return process_ranges(__self);
-}
-
-template <typename _RandomAccessIterator1, typename _RandomAccessIterator2, typename _Compare, typename _LeafSort>
-class __stable_sort_func
-{
-  public:
-    typedef typename std::iterator_traits<_RandomAccessIterator1>::
diff erence_type _DifferenceType1;
-    typedef typename std::iterator_traits<_RandomAccessIterator2>::
diff erence_type _DifferenceType2;
-    typedef typename std::common_type<_DifferenceType1, _DifferenceType2>::type _SizeType;
-
-  private:
-    _RandomAccessIterator1 _M_xs, _M_xe, _M_x_beg;
-    _RandomAccessIterator2 _M_zs, _M_z_beg;
-    _Compare _M_comp;
-    _LeafSort _M_leaf_sort;
-    bool _M_root;
-    _SizeType _M_nsort; //zero or number of elements to be sorted for partial_sort alforithm
-
-  public:
-    __stable_sort_func(_RandomAccessIterator1 __xs, _RandomAccessIterator1 __xe, _RandomAccessIterator2 __zs,
-                       bool __root, _Compare __comp, _LeafSort __leaf_sort, _SizeType __nsort,
-                       _RandomAccessIterator1 __x_beg, _RandomAccessIterator2 __z_beg)
-        : _M_xs(__xs), _M_xe(__xe), _M_x_beg(__x_beg), _M_zs(__zs), _M_z_beg(__z_beg), _M_comp(__comp),
-          _M_leaf_sort(__leaf_sort), _M_root(__root), _M_nsort(__nsort)
-    {
-    }
-
-    __task*
-    operator()(__task* __self);
-};
-
-#define _PSTL_STABLE_SORT_CUT_OFF 500
-
-template <typename _RandomAccessIterator1, typename _RandomAccessIterator2, typename _Compare, typename _LeafSort>
-__task*
-__stable_sort_func<_RandomAccessIterator1, _RandomAccessIterator2, _Compare, _LeafSort>::operator()(__task* __self)
-{
-    typedef __merge_func<_RandomAccessIterator1, _RandomAccessIterator2, _Compare, __utils::__serial_destroy,
-                         __utils::__serial_move_merge>
-        _MergeTaskType;
-
-    const _SizeType __n = _M_xe - _M_xs;
-    const _SizeType __nmerge = _M_nsort > 0 ? _M_nsort : __n;
-    const _SizeType __sort_cut_off = _PSTL_STABLE_SORT_CUT_OFF;
-    if (__n <= __sort_cut_off)
-    {
-        _M_leaf_sort(_M_xs, _M_xe, _M_comp);
-        _LIBCPP_ASSERT_UNCATEGORIZED(!_M_root, "");
-        return nullptr;
-    }
-
-    const _RandomAccessIterator1 __xm = _M_xs + __n / 2;
-    const _RandomAccessIterator2 __zm = _M_zs + (__xm - _M_xs);
-    const _RandomAccessIterator2 __ze = _M_zs + __n;
-    _MergeTaskType __m(_MergeTaskType(_M_xs - _M_x_beg, __xm - _M_x_beg, __xm - _M_x_beg, _M_xe - _M_x_beg,
-                                      _M_zs - _M_z_beg, _M_comp, __utils::__serial_destroy(),
-                                      __utils::__serial_move_merge(__nmerge), _M_nsort, _M_x_beg, _M_z_beg,
-                                      /*x_orig*/ true, /*y_orig*/ true, /*root*/ _M_root));
-    auto __parent = __self->make_continuation(std::move(__m));
-    __parent->set_ref_count(2);
-    auto __right = __self->make_child_of(
-        __parent, __stable_sort_func(__xm, _M_xe, __zm, false, _M_comp, _M_leaf_sort, _M_nsort, _M_x_beg, _M_z_beg));
-    __self->spawn(__right);
-    __self->recycle_as_child_of(__parent);
-    _M_root = false;
-    _M_xe = __xm;
-
-    return __self;
-}
-
-template <class _ExecutionPolicy, typename _RandomAccessIterator, typename _Compare, typename _LeafSort>
-void
-__parallel_stable_sort(__pstl::__internal::__tbb_backend_tag, _ExecutionPolicy&&, _RandomAccessIterator __xs,
-                       _RandomAccessIterator __xe, _Compare __comp, _LeafSort __leaf_sort, std::size_t __nsort = 0)
-{
-    tbb::this_task_arena::isolate([=, &__nsort]() {
-        //sorting based on task tree and parallel merge
-        typedef typename std::iterator_traits<_RandomAccessIterator>::value_type _ValueType;
-        typedef typename std::iterator_traits<_RandomAccessIterator>::
diff erence_type _DifferenceType;
-        const _DifferenceType __n = __xe - __xs;
-        if (__nsort == __n)
-            __nsort = 0; // 'partial_sort' becames 'sort'
-
-        const _DifferenceType __sort_cut_off = _PSTL_STABLE_SORT_CUT_OFF;
-        if (__n > __sort_cut_off)
-        {
-            __buffer<_ValueType> __buf(__n);
-            __root_task<__stable_sort_func<_RandomAccessIterator, _ValueType*, _Compare, _LeafSort>> __root{
-                __xs, __xe, __buf.get(), true, __comp, __leaf_sort, __nsort, __xs, __buf.get()};
-            __task::spawn_root_and_wait(__root);
-            return;
-        }
-        //serial sort
-        __leaf_sort(__xs, __xe, __comp);
-    });
-}
-
-//------------------------------------------------------------------------
-// parallel_merge
-//------------------------------------------------------------------------
-template <typename _RandomAccessIterator1, typename _RandomAccessIterator2, typename _RandomAccessIterator3,
-          typename _Compare, typename _LeafMerge>
-class __merge_func_static
-{
-    _RandomAccessIterator1 _M_xs, _M_xe;
-    _RandomAccessIterator2 _M_ys, _M_ye;
-    _RandomAccessIterator3 _M_zs;
-    _Compare _M_comp;
-    _LeafMerge _M_leaf_merge;
-
-  public:
-    __merge_func_static(_RandomAccessIterator1 __xs, _RandomAccessIterator1 __xe, _RandomAccessIterator2 __ys,
-                        _RandomAccessIterator2 __ye, _RandomAccessIterator3 __zs, _Compare __comp,
-                        _LeafMerge __leaf_merge)
-        : _M_xs(__xs), _M_xe(__xe), _M_ys(__ys), _M_ye(__ye), _M_zs(__zs), _M_comp(__comp), _M_leaf_merge(__leaf_merge)
-    {
-    }
-
-    __task*
-    operator()(__task* __self);
-};
-
-//TODO: consider usage of parallel_for with a custom blocked_range
-template <typename _RandomAccessIterator1, typename _RandomAccessIterator2, typename _RandomAccessIterator3,
-          typename __M_Compare, typename _LeafMerge>
-__task*
-__merge_func_static<_RandomAccessIterator1, _RandomAccessIterator2, _RandomAccessIterator3, __M_Compare, _LeafMerge>::
-operator()(__task* __self)
-{
-    typedef typename std::iterator_traits<_RandomAccessIterator1>::
diff erence_type _DifferenceType1;
-    typedef typename std::iterator_traits<_RandomAccessIterator2>::
diff erence_type _DifferenceType2;
-    typedef typename std::common_type<_DifferenceType1, _DifferenceType2>::type _SizeType;
-    const _SizeType __n = (_M_xe - _M_xs) + (_M_ye - _M_ys);
-    const _SizeType __merge_cut_off = _PSTL_MERGE_CUT_OFF;
-    if (__n <= __merge_cut_off)
-    {
-        _M_leaf_merge(_M_xs, _M_xe, _M_ys, _M_ye, _M_zs, _M_comp);
-        return nullptr;
-    }
-
-    _RandomAccessIterator1 __xm;
-    _RandomAccessIterator2 __ym;
-    if (_M_xe - _M_xs < _M_ye - _M_ys)
-    {
-        __ym = _M_ys + (_M_ye - _M_ys) / 2;
-        __xm = std::upper_bound(_M_xs, _M_xe, *__ym, _M_comp);
-    }
-    else
-    {
-        __xm = _M_xs + (_M_xe - _M_xs) / 2;
-        __ym = std::lower_bound(_M_ys, _M_ye, *__xm, _M_comp);
-    }
-    const _RandomAccessIterator3 __zm = _M_zs + ((__xm - _M_xs) + (__ym - _M_ys));
-    auto __right = __self->make_additional_child_of(
-        __self->parent(), __merge_func_static(__xm, _M_xe, __ym, _M_ye, __zm, _M_comp, _M_leaf_merge));
-    __self->spawn(__right);
-    __self->recycle_as_continuation();
-    _M_xe = __xm;
-    _M_ye = __ym;
-
-    return __self;
-}
-
-template <class _ExecutionPolicy, typename _RandomAccessIterator1, typename _RandomAccessIterator2,
-          typename _RandomAccessIterator3, typename _Compare, typename _LeafMerge>
-void
-__parallel_merge(__pstl::__internal::__tbb_backend_tag, _ExecutionPolicy&&, _RandomAccessIterator1 __xs,
-                 _RandomAccessIterator1 __xe, _RandomAccessIterator2 __ys, _RandomAccessIterator2 __ye,
-                 _RandomAccessIterator3 __zs, _Compare __comp, _LeafMerge __leaf_merge)
-{
-    typedef typename std::iterator_traits<_RandomAccessIterator1>::
diff erence_type _DifferenceType1;
-    typedef typename std::iterator_traits<_RandomAccessIterator2>::
diff erence_type _DifferenceType2;
-    typedef typename std::common_type<_DifferenceType1, _DifferenceType2>::type _SizeType;
-    const _SizeType __n = (__xe - __xs) + (__ye - __ys);
-    const _SizeType __merge_cut_off = _PSTL_MERGE_CUT_OFF;
-    if (__n <= __merge_cut_off)
-    {
-        // Fall back on serial merge
-        __leaf_merge(__xs, __xe, __ys, __ye, __zs, __comp);
-    }
-    else
-    {
-        tbb::this_task_arena::isolate([=]() {
-            typedef __merge_func_static<_RandomAccessIterator1, _RandomAccessIterator2, _RandomAccessIterator3,
-                                        _Compare, _LeafMerge>
-                _TaskType;
-            __root_task<_TaskType> __root{__xs, __xe, __ys, __ye, __zs, __comp, __leaf_merge};
-            __task::spawn_root_and_wait(__root);
-        });
-    }
-}
-
-//------------------------------------------------------------------------
-// parallel_invoke
-//------------------------------------------------------------------------
-template <class _ExecutionPolicy, typename _F1, typename _F2>
-void
-__parallel_invoke(__pstl::__internal::__tbb_backend_tag, _ExecutionPolicy&&, _F1&& __f1, _F2&& __f2)
-{
-    //TODO: a version of tbb::this_task_arena::isolate with variadic arguments pack should be added in the future
-    tbb::this_task_arena::isolate([&]() { tbb::parallel_invoke(std::forward<_F1>(__f1), std::forward<_F2>(__f2)); });
-}
-
-} // namespace __tbb_backend
-} // namespace __pstl
-
-#endif /* _PSTL_PARALLEL_BACKEND_TBB_H */

diff  --git a/libcxx/include/__pstl/internal/parallel_backend_utils.h b/libcxx/include/__pstl/internal/parallel_backend_utils.h
deleted file mode 100644
index 8adcdb71f86789..00000000000000
--- a/libcxx/include/__pstl/internal/parallel_backend_utils.h
+++ /dev/null
@@ -1,260 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_PARALLEL_BACKEND_UTILS_H
-#define _PSTL_PARALLEL_BACKEND_UTILS_H
-
-#include <__assert>
-#include <__config>
-#include <__iterator/iterator_traits.h>
-#include <__memory/addressof.h>
-
-#include "utils.h"
-
-namespace __pstl
-{
-
-namespace __utils
-{
-
-//! Destroy sequence [xs,xe)
-struct __serial_destroy
-{
-    template <typename _RandomAccessIterator>
-    void
-    operator()(_RandomAccessIterator __zs, _RandomAccessIterator __ze)
-    {
-        typedef typename std::iterator_traits<_RandomAccessIterator>::value_type _ValueType;
-        while (__zs != __ze)
-        {
-            --__ze;
-            (*__ze).~_ValueType();
-        }
-    }
-};
-
-//! Merge sequences [__xs,__xe) and [__ys,__ye) to output sequence [__zs,(__xe-__xs)+(__ye-__ys)), using std::move
-struct __serial_move_merge
-{
-    const std::size_t _M_nmerge;
-
-    explicit __serial_move_merge(std::size_t __nmerge) : _M_nmerge(__nmerge) {}
-    template <class _RandomAccessIterator1, class _RandomAccessIterator2, class _RandomAccessIterator3, class _Compare,
-              class _MoveValueX, class _MoveValueY, class _MoveSequenceX, class _MoveSequenceY>
-    void
-    operator()(_RandomAccessIterator1 __xs, _RandomAccessIterator1 __xe, _RandomAccessIterator2 __ys,
-               _RandomAccessIterator2 __ye, _RandomAccessIterator3 __zs, _Compare __comp, _MoveValueX __move_value_x,
-               _MoveValueY __move_value_y, _MoveSequenceX __move_sequence_x, _MoveSequenceY __move_sequence_y)
-    {
-        constexpr bool __same_move_val = std::is_same<_MoveValueX, _MoveValueY>::value;
-        constexpr bool __same_move_seq = std::is_same<_MoveSequenceX, _MoveSequenceY>::value;
-
-        auto __n = _M_nmerge;
-        _LIBCPP_ASSERT_UNCATEGORIZED(__n > 0, "");
-
-        auto __nx = __xe - __xs;
-        //auto __ny = __ye - __ys;
-        _RandomAccessIterator3 __zs_beg = __zs;
-
-        if (__xs != __xe)
-        {
-            if (__ys != __ye)
-            {
-                for (;;)
-                {
-                    if (__comp(*__ys, *__xs))
-                    {
-                        const auto __i = __zs - __zs_beg;
-                        if (__i < __nx)
-                            __move_value_x(__ys, __zs);
-                        else
-                            __move_value_y(__ys, __zs);
-                        ++__zs, --__n;
-                        if (++__ys == __ye)
-                        {
-                            break;
-                        }
-                        else if (__n == 0)
-                        {
-                            const auto __j = __zs - __zs_beg;
-                            if (__same_move_seq || __j < __nx)
-                                __zs = __move_sequence_x(__ys, __ye, __zs);
-                            else
-                                __zs = __move_sequence_y(__ys, __ye, __zs);
-                            break;
-                        }
-                    }
-                    else
-                    {
-                        const auto __i = __zs - __zs_beg;
-                        if (__same_move_val || __i < __nx)
-                            __move_value_x(__xs, __zs);
-                        else
-                            __move_value_y(__xs, __zs);
-                        ++__zs, --__n;
-                        if (++__xs == __xe)
-                        {
-                            const auto __j = __zs - __zs_beg;
-                            if (__same_move_seq || __j < __nx)
-                                __move_sequence_x(__ys, __ye, __zs);
-                            else
-                                __move_sequence_y(__ys, __ye, __zs);
-                            return;
-                        }
-                        else if (__n == 0)
-                        {
-                            const auto __j = __zs - __zs_beg;
-                            if (__same_move_seq || __j < __nx)
-                            {
-                                __zs = __move_sequence_x(__xs, __xe, __zs);
-                                __move_sequence_x(__ys, __ye, __zs);
-                            }
-                            else
-                            {
-                                __zs = __move_sequence_y(__xs, __xe, __zs);
-                                __move_sequence_y(__ys, __ye, __zs);
-                            }
-                            return;
-                        }
-                    }
-                }
-            }
-            __ys = __xs;
-            __ye = __xe;
-        }
-        const auto __i = __zs - __zs_beg;
-        if (__same_move_seq || __i < __nx)
-            __move_sequence_x(__ys, __ye, __zs);
-        else
-            __move_sequence_y(__ys, __ye, __zs);
-    }
-};
-
-template <typename _ForwardIterator1, typename _ForwardIterator2, typename _OutputIterator, typename _Compare,
-          typename _CopyConstructRange>
-_OutputIterator
-__set_union_construct(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
-                      _ForwardIterator2 __last2, _OutputIterator __result, _Compare __comp,
-                      _CopyConstructRange __cc_range)
-{
-    using _Tp = typename std::iterator_traits<_OutputIterator>::value_type;
-
-    for (; __first1 != __last1; ++__result)
-    {
-        if (__first2 == __last2)
-            return __cc_range(__first1, __last1, __result);
-        if (__comp(*__first2, *__first1))
-        {
-            ::new (std::addressof(*__result)) _Tp(*__first2);
-            ++__first2;
-        }
-        else
-        {
-            ::new (std::addressof(*__result)) _Tp(*__first1);
-            if (!__comp(*__first1, *__first2))
-                ++__first2;
-            ++__first1;
-        }
-    }
-    return __cc_range(__first2, __last2, __result);
-}
-
-template <typename _ForwardIterator1, typename _ForwardIterator2, typename _OutputIterator, typename _Compare>
-_OutputIterator
-__set_intersection_construct(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
-                             _ForwardIterator2 __last2, _OutputIterator __result, _Compare __comp)
-{
-    using _Tp = typename std::iterator_traits<_OutputIterator>::value_type;
-
-    for (; __first1 != __last1 && __first2 != __last2;)
-    {
-        if (__comp(*__first1, *__first2))
-            ++__first1;
-        else
-        {
-            if (!__comp(*__first2, *__first1))
-            {
-                ::new (std::addressof(*__result)) _Tp(*__first1);
-                ++__result;
-                ++__first1;
-            }
-            ++__first2;
-        }
-    }
-    return __result;
-}
-
-template <typename _ForwardIterator1, typename _ForwardIterator2, typename _OutputIterator, typename _Compare,
-          typename _CopyConstructRange>
-_OutputIterator
-__set_
diff erence_construct(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
-                           _ForwardIterator2 __last2, _OutputIterator __result, _Compare __comp,
-                           _CopyConstructRange __cc_range)
-{
-    using _Tp = typename std::iterator_traits<_OutputIterator>::value_type;
-
-    for (; __first1 != __last1;)
-    {
-        if (__first2 == __last2)
-            return __cc_range(__first1, __last1, __result);
-
-        if (__comp(*__first1, *__first2))
-        {
-            ::new (std::addressof(*__result)) _Tp(*__first1);
-            ++__result;
-            ++__first1;
-        }
-        else
-        {
-            if (!__comp(*__first2, *__first1))
-                ++__first1;
-            ++__first2;
-        }
-    }
-    return __result;
-}
-template <typename _ForwardIterator1, typename _ForwardIterator2, typename _OutputIterator, typename _Compare,
-          typename _CopyConstructRange>
-_OutputIterator
-__set_symmetric_
diff erence_construct(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2,
-                                     _ForwardIterator2 __last2, _OutputIterator __result, _Compare __comp,
-                                     _CopyConstructRange __cc_range)
-{
-    using _Tp = typename std::iterator_traits<_OutputIterator>::value_type;
-
-    for (; __first1 != __last1;)
-    {
-        if (__first2 == __last2)
-            return __cc_range(__first1, __last1, __result);
-
-        if (__comp(*__first1, *__first2))
-        {
-            ::new (std::addressof(*__result)) _Tp(*__first1);
-            ++__result;
-            ++__first1;
-        }
-        else
-        {
-            if (__comp(*__first2, *__first1))
-            {
-                ::new (std::addressof(*__result)) _Tp(*__first2);
-                ++__result;
-            }
-            else
-                ++__first1;
-            ++__first2;
-        }
-    }
-    return __cc_range(__first2, __last2, __result);
-}
-
-} // namespace __utils
-} // namespace __pstl
-
-#endif /* _PSTL_PARALLEL_BACKEND_UTILS_H */

diff  --git a/libcxx/include/__pstl/internal/unseq_backend_simd.h b/libcxx/include/__pstl/internal/unseq_backend_simd.h
deleted file mode 100644
index c64c178471ceae..00000000000000
--- a/libcxx/include/__pstl/internal/unseq_backend_simd.h
+++ /dev/null
@@ -1,697 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_UNSEQ_BACKEND_SIMD_H
-#define _PSTL_UNSEQ_BACKEND_SIMD_H
-
-#include <__config>
-#include <__functional/operations.h>
-#include <__iterator/iterator_traits.h>
-#include <__type_traits/is_arithmetic.h>
-#include <__type_traits/is_same.h>
-#include <__utility/move.h>
-#include <__utility/pair.h>
-#include <cstddef>
-#include <cstdint>
-
-#include <__pstl/internal/utils.h>
-
-// This header defines the minimum set of vector routines required
-// to support parallel STL.
-
-#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
-namespace __pstl
-{
-namespace __unseq_backend
-{
-
-// Expect vector width up to 64 (or 512 bit)
-const std::size_t __lane_size = 64;
-
-template <class _Iterator, class _DifferenceType, class _Function>
-_LIBCPP_HIDE_FROM_ABI _Iterator
-__simd_walk_1(_Iterator __first, _DifferenceType __n, _Function __f) noexcept
-{
-    _PSTL_PRAGMA_SIMD
-    for (_DifferenceType __i = 0; __i < __n; ++__i)
-        __f(__first[__i]);
-
-    return __first + __n;
-}
-
-template <class _Iterator1, class _DifferenceType, class _Iterator2, class _Function>
-_LIBCPP_HIDE_FROM_ABI _Iterator2
-__simd_walk_2(_Iterator1 __first1, _DifferenceType __n, _Iterator2 __first2, _Function __f) noexcept
-{
-    _PSTL_PRAGMA_SIMD
-    for (_DifferenceType __i = 0; __i < __n; ++__i)
-        __f(__first1[__i], __first2[__i]);
-    return __first2 + __n;
-}
-
-template <class _Iterator1, class _DifferenceType, class _Iterator2, class _Iterator3, class _Function>
-_LIBCPP_HIDE_FROM_ABI _Iterator3
-__simd_walk_3(_Iterator1 __first1, _DifferenceType __n, _Iterator2 __first2, _Iterator3 __first3,
-              _Function __f) noexcept
-{
-    _PSTL_PRAGMA_SIMD
-    for (_DifferenceType __i = 0; __i < __n; ++__i)
-        __f(__first1[__i], __first2[__i], __first3[__i]);
-    return __first3 + __n;
-}
-
-// TODO: check whether __simd_first() can be used here
-template <class _Index, class _DifferenceType, class _Pred>
-_LIBCPP_HIDE_FROM_ABI bool
-__simd_or(_Index __first, _DifferenceType __n, _Pred __pred) noexcept
-{
-    _DifferenceType __block_size = 4 < __n ? 4 : __n;
-    const _Index __last = __first + __n;
-    while (__last != __first)
-    {
-        int32_t __flag = 1;
-        _PSTL_PRAGMA_SIMD_REDUCTION(& : __flag)
-        for (_DifferenceType __i = 0; __i < __block_size; ++__i)
-            if (__pred(*(__first + __i)))
-                __flag = 0;
-        if (!__flag)
-            return true;
-
-        __first += __block_size;
-        if (__last - __first >= __block_size << 1)
-        {
-            // Double the block _Size.  Any unnecessary iterations can be amortized against work done so far.
-            __block_size <<= 1;
-        }
-        else
-        {
-            __block_size = __last - __first;
-        }
-    }
-    return false;
-}
-
-template <class _Index1, class _DifferenceType, class _Index2, class _Pred>
-_LIBCPP_HIDE_FROM_ABI std::pair<_Index1, _Index2>
-__simd_first(_Index1 __first1, _DifferenceType __n, _Index2 __first2, _Pred __pred) noexcept
-{
-    const _Index1 __last1 = __first1 + __n;
-    const _Index2 __last2 = __first2 + __n;
-    // Experiments show good block sizes like this
-    const _DifferenceType __block_size = 8;
-    alignas(__lane_size) _DifferenceType __lane[__block_size] = {0};
-    while (__last1 - __first1 >= __block_size)
-    {
-        _DifferenceType __found = 0;
-        _DifferenceType __i;
-            _PSTL_PRAGMA_SIMD_REDUCTION(|
-                                        : __found) for (__i = 0; __i < __block_size; ++__i)
-        {
-            const _DifferenceType __t = __pred(__first1[__i], __first2[__i]);
-            __lane[__i] = __t;
-            __found |= __t;
-        }
-        if (__found)
-        {
-            _DifferenceType __i2;
-            // This will vectorize
-            for (__i2 = 0; __i2 < __block_size; ++__i2)
-            {
-                if (__lane[__i2])
-                    break;
-            }
-            return std::make_pair(__first1 + __i2, __first2 + __i2);
-        }
-        __first1 += __block_size;
-        __first2 += __block_size;
-    }
-
-    //Keep remainder scalar
-    for (; __last1 != __first1; ++__first1, ++__first2)
-        if (__pred(*(__first1), *(__first2)))
-            return std::make_pair(__first1, __first2);
-
-    return std::make_pair(__last1, __last2);
-}
-
-template <class _Index, class _DifferenceType, class _Pred>
-_LIBCPP_HIDE_FROM_ABI _DifferenceType
-__simd_count(_Index __index, _DifferenceType __n, _Pred __pred) noexcept
-{
-    _DifferenceType __count = 0;
-    _PSTL_PRAGMA_SIMD_REDUCTION(+ : __count)
-    for (_DifferenceType __i = 0; __i < __n; ++__i)
-        if (__pred(*(__index + __i)))
-            ++__count;
-
-    return __count;
-}
-
-template <class _InputIterator, class _DifferenceType, class _OutputIterator, class _BinaryPredicate>
-_LIBCPP_HIDE_FROM_ABI _OutputIterator
-__simd_unique_copy(_InputIterator __first, _DifferenceType __n, _OutputIterator __result,
-                   _BinaryPredicate __pred) noexcept
-{
-    if (__n == 0)
-        return __result;
-
-    _DifferenceType __cnt = 1;
-    __result[0] = __first[0];
-
-    _PSTL_PRAGMA_SIMD
-    for (_DifferenceType __i = 1; __i < __n; ++__i)
-    {
-        if (!__pred(__first[__i], __first[__i - 1]))
-        {
-            __result[__cnt] = __first[__i];
-            ++__cnt;
-        }
-    }
-    return __result + __cnt;
-}
-
-template <class _InputIterator, class _DifferenceType, class _OutputIterator, class _Assigner>
-_LIBCPP_HIDE_FROM_ABI _OutputIterator
-__simd_assign(_InputIterator __first, _DifferenceType __n, _OutputIterator __result, _Assigner __assigner) noexcept
-{
-    _PSTL_USE_NONTEMPORAL_STORES_IF_ALLOWED
-    _PSTL_PRAGMA_SIMD
-    for (_DifferenceType __i = 0; __i < __n; ++__i)
-        __assigner(__first + __i, __result + __i);
-    return __result + __n;
-}
-
-template <class _InputIterator, class _DifferenceType, class _OutputIterator, class _UnaryPredicate>
-_LIBCPP_HIDE_FROM_ABI _OutputIterator
-__simd_copy_if(_InputIterator __first, _DifferenceType __n, _OutputIterator __result, _UnaryPredicate __pred) noexcept
-{
-    _DifferenceType __cnt = 0;
-
-    _PSTL_PRAGMA_SIMD
-    for (_DifferenceType __i = 0; __i < __n; ++__i)
-    {
-        if (__pred(__first[__i]))
-        {
-            __result[__cnt] = __first[__i];
-            ++__cnt;
-        }
-    }
-    return __result + __cnt;
-}
-
-template <class _InputIterator, class _DifferenceType, class _BinaryPredicate>
-_LIBCPP_HIDE_FROM_ABI _DifferenceType
-__simd_calc_mask_2(_InputIterator __first, _DifferenceType __n, bool* __mask, _BinaryPredicate __pred) noexcept
-{
-    _DifferenceType __count = 0;
-
-    _PSTL_PRAGMA_SIMD_REDUCTION(+ : __count)
-    for (_DifferenceType __i = 0; __i < __n; ++__i)
-    {
-        __mask[__i] = !__pred(__first[__i], __first[__i - 1]);
-        __count += __mask[__i];
-    }
-    return __count;
-}
-
-template <class _InputIterator, class _DifferenceType, class _UnaryPredicate>
-_LIBCPP_HIDE_FROM_ABI _DifferenceType
-__simd_calc_mask_1(_InputIterator __first, _DifferenceType __n, bool* __mask, _UnaryPredicate __pred) noexcept
-{
-    _DifferenceType __count = 0;
-
-    _PSTL_PRAGMA_SIMD_REDUCTION(+ : __count)
-    for (_DifferenceType __i = 0; __i < __n; ++__i)
-    {
-        __mask[__i] = __pred(__first[__i]);
-        __count += __mask[__i];
-    }
-    return __count;
-}
-
-template <class _InputIterator, class _DifferenceType, class _OutputIterator, class _Assigner>
-_LIBCPP_HIDE_FROM_ABI void
-__simd_copy_by_mask(_InputIterator __first, _DifferenceType __n, _OutputIterator __result, bool* __mask,
-                    _Assigner __assigner) noexcept
-{
-    _DifferenceType __cnt = 0;
-    _PSTL_PRAGMA_SIMD
-    for (_DifferenceType __i = 0; __i < __n; ++__i)
-    {
-        if (__mask[__i])
-        {
-            {
-                __assigner(__first + __i, __result + __cnt);
-                ++__cnt;
-            }
-        }
-    }
-}
-
-template <class _InputIterator, class _DifferenceType, class _OutputIterator1, class _OutputIterator2>
-_LIBCPP_HIDE_FROM_ABI void
-__simd_partition_by_mask(_InputIterator __first, _DifferenceType __n, _OutputIterator1 __out_true,
-                         _OutputIterator2 __out_false, bool* __mask) noexcept
-{
-    _DifferenceType __cnt_true = 0, __cnt_false = 0;
-    _PSTL_PRAGMA_SIMD
-    for (_DifferenceType __i = 0; __i < __n; ++__i)
-    {
-        if (__mask[__i])
-        {
-            __out_true[__cnt_true] = __first[__i];
-            ++__cnt_true;
-        }
-        else
-        {
-            __out_false[__cnt_false] = __first[__i];
-            ++__cnt_false;
-        }
-    }
-}
-
-template <class _Index, class _DifferenceType, class _Generator>
-_LIBCPP_HIDE_FROM_ABI _Index
-__simd_generate_n(_Index __first, _DifferenceType __size, _Generator __g) noexcept
-{
-    _PSTL_USE_NONTEMPORAL_STORES_IF_ALLOWED
-    _PSTL_PRAGMA_SIMD
-    for (_DifferenceType __i = 0; __i < __size; ++__i)
-        __first[__i] = __g();
-    return __first + __size;
-}
-
-template <class _Index, class _BinaryPredicate>
-_LIBCPP_HIDE_FROM_ABI _Index
-__simd_adjacent_find(_Index __first, _Index __last, _BinaryPredicate __pred, bool __or_semantic) noexcept
-{
-    if (__last - __first < 2)
-        return __last;
-
-    typedef typename std::iterator_traits<_Index>::
diff erence_type _DifferenceType;
-    _DifferenceType __i = 0;
-
-    // Experiments show good block sizes like this
-    //TODO: to consider tuning block_size for various data types
-    const _DifferenceType __block_size = 8;
-    alignas(__lane_size) _DifferenceType __lane[__block_size] = {0};
-    while (__last - __first >= __block_size)
-    {
-        _DifferenceType __found = 0;
-            _PSTL_PRAGMA_SIMD_REDUCTION(|
-                                        : __found) for (__i = 0; __i < __block_size - 1; ++__i)
-        {
-            //TODO: to improve SIMD vectorization
-            const _DifferenceType __t = __pred(*(__first + __i), *(__first + __i + 1));
-            __lane[__i] = __t;
-            __found |= __t;
-        }
-
-        //Process a pair of elements on a boundary of a data block
-        if (__first + __block_size < __last && __pred(*(__first + __i), *(__first + __i + 1)))
-            __lane[__i] = __found = 1;
-
-        if (__found)
-        {
-            if (__or_semantic)
-                return __first;
-
-            // This will vectorize
-            for (__i = 0; __i < __block_size; ++__i)
-                if (__lane[__i])
-                    break;
-            return __first + __i; //As far as found is true a __result (__lane[__i] is true) is guaranteed
-        }
-        __first += __block_size;
-    }
-    //Process the rest elements
-    for (; __last - __first > 1; ++__first)
-        if (__pred(*__first, *(__first + 1)))
-            return __first;
-
-    return __last;
-}
-
-// It was created to reduce the code inside std::enable_if
-template <typename _Tp, typename _BinaryOperation>
-using is_arithmetic_plus = std::integral_constant<bool, std::is_arithmetic<_Tp>::value &&
-                                                            std::is_same<_BinaryOperation, std::plus<_Tp>>::value>;
-
-// Exclusive scan for "+" and arithmetic types
-template <class _InputIterator, class _Size, class _OutputIterator, class _UnaryOperation, class _Tp,
-          class _BinaryOperation>
-_LIBCPP_HIDE_FROM_ABI
-typename std::enable_if<is_arithmetic_plus<_Tp, _BinaryOperation>::value, std::pair<_OutputIterator, _Tp>>::type
-__simd_scan(_InputIterator __first, _Size __n, _OutputIterator __result, _UnaryOperation __unary_op, _Tp __init,
-            _BinaryOperation, /*Inclusive*/ std::false_type)
-{
-    _PSTL_PRAGMA_SIMD_SCAN(+ : __init)
-    for (_Size __i = 0; __i < __n; ++__i)
-    {
-        __result[__i] = __init;
-        _PSTL_PRAGMA_SIMD_EXCLUSIVE_SCAN(__init)
-        __init += __unary_op(__first[__i]);
-    }
-    return std::make_pair(__result + __n, __init);
-}
-
-// As soon as we cannot call __binary_op in "combiner" we create a wrapper over _Tp to encapsulate __binary_op
-template <typename _Tp, typename _BinaryOp>
-struct _Combiner
-{
-    _Tp __value_;
-    _BinaryOp* __bin_op_; // Here is a pointer to function because of default ctor
-
-    _LIBCPP_HIDE_FROM_ABI _Combiner() : __value_{}, __bin_op_(nullptr) {}
-    _LIBCPP_HIDE_FROM_ABI
-    _Combiner(const _Tp& __value, const _BinaryOp* __bin_op)
-        : __value_(__value), __bin_op_(const_cast<_BinaryOp*>(__bin_op)) {}
-    _LIBCPP_HIDE_FROM_ABI _Combiner(const _Combiner& __obj) : __value_{}, __bin_op_(__obj.__bin_op) {}
-
-    _LIBCPP_HIDE_FROM_ABI void
-    operator()(const _Combiner& __obj)
-    {
-        __value_ = (*__bin_op_)(__value_, __obj.__value_);
-    }
-};
-
-// Exclusive scan for other binary operations and types
-template <class _InputIterator, class _Size, class _OutputIterator, class _UnaryOperation, class _Tp,
-          class _BinaryOperation>
-_LIBCPP_HIDE_FROM_ABI
-typename std::enable_if<!is_arithmetic_plus<_Tp, _BinaryOperation>::value, std::pair<_OutputIterator, _Tp>>::type
-__simd_scan(_InputIterator __first, _Size __n, _OutputIterator __result, _UnaryOperation __unary_op, _Tp __init,
-            _BinaryOperation __binary_op, /*Inclusive*/ std::false_type)
-{
-    typedef _Combiner<_Tp, _BinaryOperation> _CombinerType;
-    _CombinerType __combined_init{__init, &__binary_op};
-
-    _PSTL_PRAGMA_DECLARE_REDUCTION(__bin_op, _CombinerType)
-    _PSTL_PRAGMA_SIMD_SCAN(__bin_op : __combined_init)
-    for (_Size __i = 0; __i < __n; ++__i)
-    {
-        __result[__i] = __combined_init.__value_;
-        _PSTL_PRAGMA_SIMD_EXCLUSIVE_SCAN(__combined_init)
-        __combined_init.__value_ = __binary_op(__combined_init.__value_, __unary_op(__first[__i]));
-    }
-    return std::make_pair(__result + __n, __combined_init.__value_);
-}
-
-// Inclusive scan for "+" and arithmetic types
-template <class _InputIterator, class _Size, class _OutputIterator, class _UnaryOperation, class _Tp,
-          class _BinaryOperation>
-_LIBCPP_HIDE_FROM_ABI
-typename std::enable_if<is_arithmetic_plus<_Tp, _BinaryOperation>::value, std::pair<_OutputIterator, _Tp>>::type
-__simd_scan(_InputIterator __first, _Size __n, _OutputIterator __result, _UnaryOperation __unary_op, _Tp __init,
-            _BinaryOperation, /*Inclusive*/ std::true_type)
-{
-    _PSTL_PRAGMA_SIMD_SCAN(+ : __init)
-    for (_Size __i = 0; __i < __n; ++__i)
-    {
-        __init += __unary_op(__first[__i]);
-        _PSTL_PRAGMA_SIMD_INCLUSIVE_SCAN(__init)
-        __result[__i] = __init;
-    }
-    return std::make_pair(__result + __n, __init);
-}
-
-// Inclusive scan for other binary operations and types
-template <class _InputIterator, class _Size, class _OutputIterator, class _UnaryOperation, class _Tp,
-          class _BinaryOperation>
-_LIBCPP_HIDE_FROM_ABI
-typename std::enable_if<!is_arithmetic_plus<_Tp, _BinaryOperation>::value, std::pair<_OutputIterator, _Tp>>::type
-__simd_scan(_InputIterator __first, _Size __n, _OutputIterator __result, _UnaryOperation __unary_op, _Tp __init,
-            _BinaryOperation __binary_op, std::true_type)
-{
-    typedef _Combiner<_Tp, _BinaryOperation> _CombinerType;
-    _CombinerType __combined_init{__init, &__binary_op};
-
-    _PSTL_PRAGMA_DECLARE_REDUCTION(__bin_op, _CombinerType)
-    _PSTL_PRAGMA_SIMD_SCAN(__bin_op : __combined_init)
-    for (_Size __i = 0; __i < __n; ++__i)
-    {
-        __combined_init.__value_ = __binary_op(__combined_init.__value_, __unary_op(__first[__i]));
-        _PSTL_PRAGMA_SIMD_INCLUSIVE_SCAN(__combined_init)
-        __result[__i] = __combined_init.__value_;
-    }
-    return std::make_pair(__result + __n, __combined_init.__value_);
-}
-
-// [restriction] - std::iterator_traits<_ForwardIterator>::value_type should be DefaultConstructible.
-// complexity [violation] - We will have at most (__n-1 + number_of_lanes) comparisons instead of at most __n-1.
-template <typename _ForwardIterator, typename _Size, typename _Compare>
-_LIBCPP_HIDE_FROM_ABI _ForwardIterator
-__simd_min_element(_ForwardIterator __first, _Size __n, _Compare __comp) noexcept
-{
-    if (__n == 0)
-    {
-        return __first;
-    }
-
-    typedef typename std::iterator_traits<_ForwardIterator>::value_type _ValueType;
-    struct _ComplexType
-    {
-        _ValueType __min_val_;
-        _Size __min_ind_;
-        _Compare* __min_comp_;
-
-        _LIBCPP_HIDE_FROM_ABI _ComplexType() : __min_val_{}, __min_ind_{}, __min_comp_(nullptr) {}
-        _LIBCPP_HIDE_FROM_ABI _ComplexType(const _ValueType& __val, const _Compare* __comp)
-            : __min_val_(__val), __min_ind_(0), __min_comp_(const_cast<_Compare*>(__comp))
-        {
-        }
-        _LIBCPP_HIDE_FROM_ABI _ComplexType(const _ComplexType& __obj)
-            : __min_val_(__obj.__min_val_), __min_ind_(__obj.__min_ind_), __min_comp_(__obj.__min_comp_)
-        {
-        }
-
-        _PSTL_PRAGMA_DECLARE_SIMD
-        _LIBCPP_HIDE_FROM_ABI void
-        operator()(const _ComplexType& __obj)
-        {
-            if (!(*__min_comp_)(__min_val_, __obj.__min_val_) &&
-                ((*__min_comp_)(__obj.__min_val_, __min_val_) || __obj.__min_ind_ - __min_ind_ < 0))
-            {
-                __min_val_ = __obj.__min_val_;
-                __min_ind_ = __obj.__min_ind_;
-            }
-        }
-    };
-
-    _ComplexType __init{*__first, &__comp};
-
-    _PSTL_PRAGMA_DECLARE_REDUCTION(__min_func, _ComplexType)
-
-    _PSTL_PRAGMA_SIMD_REDUCTION(__min_func : __init)
-    for (_Size __i = 1; __i < __n; ++__i)
-    {
-        const _ValueType __min_val = __init.__min_val_;
-        const _ValueType __current = __first[__i];
-        if (__comp(__current, __min_val))
-        {
-            __init.__min_val_ = __current;
-            __init.__min_ind_ = __i;
-        }
-    }
-    return __first + __init.__min_ind_;
-}
-
-// [restriction] - std::iterator_traits<_ForwardIterator>::value_type should be DefaultConstructible.
-// complexity [violation] - We will have at most (2*(__n-1) + 4*number_of_lanes) comparisons instead of at most [1.5*(__n-1)].
-template <typename _ForwardIterator, typename _Size, typename _Compare>
-_LIBCPP_HIDE_FROM_ABI std::pair<_ForwardIterator, _ForwardIterator>
-__simd_minmax_element(_ForwardIterator __first, _Size __n, _Compare __comp) noexcept
-{
-    if (__n == 0)
-    {
-        return std::make_pair(__first, __first);
-    }
-    typedef typename std::iterator_traits<_ForwardIterator>::value_type _ValueType;
-
-    struct _ComplexType
-    {
-        _ValueType __min_val_;
-        _ValueType __max_val_;
-        _Size __min_ind_;
-        _Size __max_ind_;
-        _Compare* __minmax_comp;
-
-        _LIBCPP_HIDE_FROM_ABI _ComplexType()
-            : __min_val_{}, __max_val_{}, __min_ind_{}, __max_ind_{}, __minmax_comp(nullptr) {}
-        _LIBCPP_HIDE_FROM_ABI _ComplexType(
-                const _ValueType& __min_val, const _ValueType& __max_val, const _Compare* __comp)
-            : __min_val_(__min_val), __max_val_(__max_val), __min_ind_(0), __max_ind_(0),
-              __minmax_comp(const_cast<_Compare*>(__comp))
-        {
-        }
-        _LIBCPP_HIDE_FROM_ABI _ComplexType(const _ComplexType& __obj)
-            : __min_val_(__obj.__min_val_), __max_val_(__obj.__max_val_), __min_ind_(__obj.__min_ind_),
-              __max_ind_(__obj.__max_ind_), __minmax_comp(__obj.__minmax_comp)
-        {
-        }
-
-        _LIBCPP_HIDE_FROM_ABI void
-        operator()(const _ComplexType& __obj)
-        {
-            // min
-            if ((*__minmax_comp)(__obj.__min_val_, __min_val_))
-            {
-                __min_val_ = __obj.__min_val_;
-                __min_ind_ = __obj.__min_ind_;
-            }
-            else if (!(*__minmax_comp)(__min_val_, __obj.__min_val_))
-            {
-                __min_val_ = __obj.__min_val_;
-                __min_ind_ = (__min_ind_ - __obj.__min_ind_ < 0) ? __min_ind_ : __obj.__min_ind_;
-            }
-
-            // max
-            if ((*__minmax_comp)(__max_val_, __obj.__max_val_))
-            {
-                __max_val_ = __obj.__max_val_;
-                __max_ind_ = __obj.__max_ind_;
-            }
-            else if (!(*__minmax_comp)(__obj.__max_val_, __max_val_))
-            {
-                __max_val_ = __obj.__max_val_;
-                __max_ind_ = (__max_ind_ - __obj.__max_ind_ < 0) ? __obj.__max_ind_ : __max_ind_;
-            }
-        }
-    };
-
-    _ComplexType __init{*__first, *__first, &__comp};
-
-    _PSTL_PRAGMA_DECLARE_REDUCTION(__min_func, _ComplexType);
-
-    _PSTL_PRAGMA_SIMD_REDUCTION(__min_func : __init)
-    for (_Size __i = 1; __i < __n; ++__i)
-    {
-        auto __min_val = __init.__min_val_;
-        auto __max_val = __init.__max_val_;
-        auto __current = __first + __i;
-        if (__comp(*__current, __min_val))
-        {
-            __init.__min_val_ = *__current;
-            __init.__min_ind_ = __i;
-        }
-        else if (!__comp(*__current, __max_val))
-        {
-            __init.__max_val_ = *__current;
-            __init.__max_ind_ = __i;
-        }
-    }
-    return std::make_pair(__first + __init.__min_ind_, __first + __init.__max_ind_);
-}
-
-template <class _InputIterator, class _DifferenceType, class _OutputIterator1, class _OutputIterator2,
-          class _UnaryPredicate>
-_LIBCPP_HIDE_FROM_ABI std::pair<_OutputIterator1, _OutputIterator2>
-__simd_partition_copy(_InputIterator __first, _DifferenceType __n, _OutputIterator1 __out_true,
-                      _OutputIterator2 __out_false, _UnaryPredicate __pred) noexcept
-{
-    _DifferenceType __cnt_true = 0, __cnt_false = 0;
-
-    _PSTL_PRAGMA_SIMD
-    for (_DifferenceType __i = 0; __i < __n; ++__i)
-    {
-        if (__pred(__first[__i]))
-        {
-            __out_true[__cnt_true] = __first[__i];
-            ++__cnt_true;
-        }
-        else
-        {
-            __out_false[__cnt_false] = __first[__i];
-            ++__cnt_false;
-        }
-    }
-    return std::make_pair(__out_true + __cnt_true, __out_false + __cnt_false);
-}
-
-template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
-_LIBCPP_HIDE_FROM_ABI _ForwardIterator1
-__simd_find_first_of(_ForwardIterator1 __first, _ForwardIterator1 __last, _ForwardIterator2 __s_first,
-                     _ForwardIterator2 __s_last, _BinaryPredicate __pred) noexcept
-{
-    typedef typename std::iterator_traits<_ForwardIterator1>::
diff erence_type _DifferencType;
-
-    const _DifferencType __n1 = __last - __first;
-    const _DifferencType __n2 = __s_last - __s_first;
-    if (__n1 == 0 || __n2 == 0)
-    {
-        return __last; // according to the standard
-    }
-
-    // Common case
-    // If first sequence larger than second then we'll run simd_first with parameters of first sequence.
-    // Otherwise, vice versa.
-    if (__n1 < __n2)
-    {
-        for (; __first != __last; ++__first)
-        {
-            if (__unseq_backend::__simd_or(
-                    __s_first, __n2,
-                    __internal::__equal_value_by_pred<decltype(*__first), _BinaryPredicate>(*__first, __pred)))
-            {
-                return __first;
-            }
-        }
-    }
-    else
-    {
-        for (; __s_first != __s_last; ++__s_first)
-        {
-            const auto __result = __unseq_backend::__simd_first(
-                __first, _DifferencType(0), __n1, [__s_first, &__pred](_ForwardIterator1 __it, _DifferencType __i) {
-                    return __pred(__it[__i], *__s_first);
-                });
-            if (__result != __last)
-            {
-                return __result;
-            }
-        }
-    }
-    return __last;
-}
-
-template <class _RandomAccessIterator, class _DifferenceType, class _UnaryPredicate>
-_LIBCPP_HIDE_FROM_ABI _RandomAccessIterator
-__simd_remove_if(_RandomAccessIterator __first, _DifferenceType __n, _UnaryPredicate __pred) noexcept
-{
-    // find first element we need to remove
-    auto __current = __unseq_backend::__simd_first(
-        __first, _DifferenceType(0), __n,
-        [&__pred](_RandomAccessIterator __it, _DifferenceType __i) { return __pred(__it[__i]); });
-    __n -= __current - __first;
-
-    // if we have in sequence only one element that pred(__current[1]) != false we can exit the function
-    if (__n < 2)
-    {
-        return __current;
-    }
-
-    _DifferenceType __cnt = 0;
-    _PSTL_PRAGMA_SIMD
-    for (_DifferenceType __i = 1; __i < __n; ++__i)
-    {
-        if (!__pred(__current[__i]))
-        {
-            __current[__cnt] = std::move(__current[__i]);
-            ++__cnt;
-        }
-    }
-    return __current + __cnt;
-}
-} // namespace __unseq_backend
-} // namespace __pstl
-
-#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
-#endif /* _PSTL_UNSEQ_BACKEND_SIMD_H */

diff  --git a/libcxx/include/__pstl/internal/utils.h b/libcxx/include/__pstl/internal/utils.h
deleted file mode 100644
index 92c8d48db5b1be..00000000000000
--- a/libcxx/include/__pstl/internal/utils.h
+++ /dev/null
@@ -1,144 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _PSTL_UTILS_H
-#define _PSTL_UTILS_H
-
-#include <__config>
-#include <__exception/terminate.h>
-#include <__utility/forward.h>
-#include <new>
-
-#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
-namespace __pstl {
-namespace __internal {
-
-template <typename _Fp>
-_LIBCPP_HIDE_FROM_ABI auto __except_handler(_Fp __f) -> decltype(__f()) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
-  try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
-    return __f();
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
-  } catch (const std::bad_alloc&) {
-    throw;            // re-throw bad_alloc according to the standard [algorithms.parallel.exceptions]
-  } catch (...) {
-    std::terminate(); // Good bye according to the standard [algorithms.parallel.exceptions]
-  }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
-}
-
-template <typename _Fp>
-_LIBCPP_HIDE_FROM_ABI void __invoke_if(std::true_type, _Fp __f) {
-  __f();
-}
-
-template <typename _Fp>
-_LIBCPP_HIDE_FROM_ABI void __invoke_if(std::false_type, _Fp) {}
-
-template <typename _Fp>
-_LIBCPP_HIDE_FROM_ABI void __invoke_if_not(std::false_type, _Fp __f) {
-  __f();
-}
-
-template <typename _Fp>
-_LIBCPP_HIDE_FROM_ABI void __invoke_if_not(std::true_type, _Fp) {}
-
-template <typename _F1, typename _F2>
-_LIBCPP_HIDE_FROM_ABI auto __invoke_if_else(std::true_type, _F1 __f1, _F2) -> decltype(__f1()) {
-  return __f1();
-}
-
-template <typename _F1, typename _F2>
-_LIBCPP_HIDE_FROM_ABI auto __invoke_if_else(std::false_type, _F1, _F2 __f2) -> decltype(__f2()) {
-  return __f2();
-}
-
-//! Unary operator that returns reference to its argument.
-struct __no_op {
-  template <typename _Tp>
-  _LIBCPP_HIDE_FROM_ABI _Tp&& operator()(_Tp&& __a) const {
-    return std::forward<_Tp>(__a);
-  }
-};
-
-template <typename _Pred>
-class __reorder_pred {
-  _Pred __pred_;
-
-public:
-  _LIBCPP_HIDE_FROM_ABI explicit __reorder_pred(_Pred __pred) : __pred_(__pred) {}
-
-  template <typename _FTp, typename _STp>
-  _LIBCPP_HIDE_FROM_ABI bool operator()(_FTp&& __a, _STp&& __b) {
-    return __pred_(std::forward<_STp>(__b), std::forward<_FTp>(__a));
-  }
-};
-
-//! Like a polymorphic lambda for pred(...,value)
-template <typename _Tp, typename _Predicate>
-class __equal_value_by_pred {
-  const _Tp& __value_;
-  _Predicate __pred_;
-
-public:
-  _LIBCPP_HIDE_FROM_ABI __equal_value_by_pred(const _Tp& __value, _Predicate __pred)
-      : __value_(__value), __pred_(__pred) {}
-
-  template <typename _Arg>
-  _LIBCPP_HIDE_FROM_ABI bool operator()(_Arg&& __arg) {
-    return __pred_(std::forward<_Arg>(__arg), __value_);
-  }
-};
-
-//! Like a polymorphic lambda for ==value
-template <typename _Tp>
-class __equal_value {
-  const _Tp& __value_;
-
-public:
-  _LIBCPP_HIDE_FROM_ABI explicit __equal_value(const _Tp& __value) : __value_(__value) {}
-
-  template <typename _Arg>
-  _LIBCPP_HIDE_FROM_ABI bool operator()(_Arg&& __arg) const {
-    return std::forward<_Arg>(__arg) == __value_;
-  }
-};
-
-//! Logical negation of ==value
-template <typename _Tp>
-class __not_equal_value {
-  const _Tp& __value_;
-
-public:
-  _LIBCPP_HIDE_FROM_ABI explicit __not_equal_value(const _Tp& __value) : __value_(__value) {}
-
-  template <typename _Arg>
-  _LIBCPP_HIDE_FROM_ABI bool operator()(_Arg&& __arg) const {
-    return !(std::forward<_Arg>(__arg) == __value_);
-  }
-};
-
-template <typename _ForwardIterator, typename _Compare>
-_LIBCPP_HIDE_FROM_ABI _ForwardIterator
-__cmp_iterators_by_values(_ForwardIterator __a, _ForwardIterator __b, _Compare __comp) {
-  if (__a < __b) { // we should return closer iterator
-    return __comp(*__b, *__a) ? __b : __a;
-  } else {
-    return __comp(*__a, *__b) ? __a : __b;
-  }
-}
-
-} // namespace __internal
-} // namespace __pstl
-
-#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
-#endif /* _PSTL_UTILS_H */

diff  --git a/libcxx/include/__pstl_algorithm b/libcxx/include/__pstl_algorithm
deleted file mode 100644
index 79c18385c5a552..00000000000000
--- a/libcxx/include/__pstl_algorithm
+++ /dev/null
@@ -1,15 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef __PSTL_ALGORITHM
-#define __PSTL_ALGORITHM
-
-#include <pstl/internal/glue_algorithm_impl.h>
-
-#endif /* __PSTL_ALGORITHM */

diff  --git a/libcxx/include/__pstl_config_site.in b/libcxx/include/__pstl_config_site.in
deleted file mode 100644
index a41a1c383a45bf..00000000000000
--- a/libcxx/include/__pstl_config_site.in
+++ /dev/null
@@ -1,17 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef __PSTL_CONFIG_SITE
-#define __PSTL_CONFIG_SITE
-
-#cmakedefine _PSTL_PAR_BACKEND_SERIAL
-#cmakedefine _PSTL_PAR_BACKEND_TBB
-#cmakedefine _PSTL_PAR_BACKEND_OPENMP
-#cmakedefine _PSTL_HIDE_FROM_ABI_PER_TU
-
-#endif // __PSTL_CONFIG_SITE

diff  --git a/libcxx/include/__pstl_memory b/libcxx/include/__pstl_memory
deleted file mode 100644
index 12b7f5aa3c04b5..00000000000000
--- a/libcxx/include/__pstl_memory
+++ /dev/null
@@ -1,15 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef __PSTL_MEMORY
-#define __PSTL_MEMORY
-
-#include <pstl/internal/glue_memory_impl.h>
-
-#endif /* __PSTL_MEMORY */

diff  --git a/libcxx/include/__pstl_numeric b/libcxx/include/__pstl_numeric
deleted file mode 100644
index cf168ef7053baf..00000000000000
--- a/libcxx/include/__pstl_numeric
+++ /dev/null
@@ -1,15 +0,0 @@
-// -*- C++ -*-
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef __PSTL_NUMERIC
-#define __PSTL_NUMERIC
-
-#include <pstl/internal/glue_numeric_impl.h>
-
-#endif /* __PSTL_NUMERIC */

diff  --git a/libcxx/include/libcxx.imp b/libcxx/include/libcxx.imp
index 0424c9bb2a5830..3eb2aa84931482 100644
--- a/libcxx/include/libcxx.imp
+++ b/libcxx/include/libcxx.imp
@@ -39,7 +39,6 @@
   { include: [ "@<__memory_resource/.*>", "private", "<memory_resource>", "public" ] },
   { include: [ "@<__mutex/.*>", "private", "<mutex>", "public" ] },
   { include: [ "@<__numeric/.*>", "private", "<numeric>", "public" ] },
-  { include: [ "@<__pstl/.*>", "private", "<pstl>", "public" ] },
   { include: [ "@<__random/.*>", "private", "<random>", "public" ] },
   { include: [ "@<__ranges/.*>", "private", "<ranges>", "public" ] },
   { include: [ "@<__stop_token/.*>", "private", "<stop_token>", "public" ] },

diff  --git a/libcxx/utils/data/ignore_format.txt b/libcxx/utils/data/ignore_format.txt
index 83e175e7c43129..36018d273f3177 100644
--- a/libcxx/utils/data/ignore_format.txt
+++ b/libcxx/utils/data/ignore_format.txt
@@ -352,24 +352,6 @@ libcxx/include/__numeric/transform_inclusive_scan.h
 libcxx/include/__numeric/transform_reduce.h
 libcxx/include/optional
 libcxx/include/ostream
-libcxx/include/__pstl/internal/numeric_impl.h
-libcxx/include/__pstl/internal/omp/parallel_for_each.h
-libcxx/include/__pstl/internal/omp/parallel_for.h
-libcxx/include/__pstl/internal/omp/parallel_invoke.h
-libcxx/include/__pstl/internal/omp/parallel_merge.h
-libcxx/include/__pstl/internal/omp/parallel_reduce.h
-libcxx/include/__pstl/internal/omp/parallel_scan.h
-libcxx/include/__pstl/internal/omp/parallel_stable_partial_sort.h
-libcxx/include/__pstl/internal/omp/parallel_stable_sort.h
-libcxx/include/__pstl/internal/omp/parallel_transform_reduce.h
-libcxx/include/__pstl/internal/omp/parallel_transform_scan.h
-libcxx/include/__pstl/internal/omp/util.h
-libcxx/include/__pstl/internal/parallel_backend.h
-libcxx/include/__pstl/internal/parallel_backend_serial.h
-libcxx/include/__pstl/internal/parallel_backend_tbb.h
-libcxx/include/__pstl/internal/parallel_backend_utils.h
-libcxx/include/__pstl/internal/unseq_backend_simd.h
-libcxx/include/__pstl/internal/utils.h
 libcxx/include/queue
 libcxx/include/__random/bernoulli_distribution.h
 libcxx/include/__random/binomial_distribution.h


        


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