[libcxx-commits] [libcxx] [libc++][pstl] Merge all frontend functions for the PSTL (PR #89219)

via libcxx-commits libcxx-commits at lists.llvm.org
Thu Apr 18 04:52:30 PDT 2024


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libcxx

Author: Louis Dionne (ldionne)

<details>
<summary>Changes</summary>

This is an intermediate step towards the PSTL dispatching mechanism rework. It will make it a lot easier to track the upcoming front-end changes. After the rework, there are basically no implementation details in the front-end, so the definition of each algorithm will become much simpler. Otherwise, it wouldn't make sense to define all the algorithms in the same header.

---

Patch is 157.04 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/89219.diff


21 Files Affected:

- (modified) libcxx/include/CMakeLists.txt (+2-18) 
- (added) libcxx/include/__algorithm/pstl.h (+1353) 
- (removed) libcxx/include/__algorithm/pstl_any_all_none_of.h (-152) 
- (removed) libcxx/include/__algorithm/pstl_copy.h (-134) 
- (removed) libcxx/include/__algorithm/pstl_count.h (-126) 
- (removed) libcxx/include/__algorithm/pstl_equal.h (-184) 
- (removed) libcxx/include/__algorithm/pstl_fill.h (-114) 
- (removed) libcxx/include/__algorithm/pstl_find.h (-141) 
- (removed) libcxx/include/__algorithm/pstl_for_each.h (-108) 
- (removed) libcxx/include/__algorithm/pstl_generate.h (-113) 
- (removed) libcxx/include/__algorithm/pstl_is_partitioned.h (-79) 
- (removed) libcxx/include/__algorithm/pstl_merge.h (-97) 
- (removed) libcxx/include/__algorithm/pstl_move.h (-89) 
- (removed) libcxx/include/__algorithm/pstl_replace.h (-260) 
- (removed) libcxx/include/__algorithm/pstl_rotate_copy.h (-90) 
- (removed) libcxx/include/__algorithm/pstl_sort.h (-85) 
- (removed) libcxx/include/__algorithm/pstl_stable_sort.h (-63) 
- (removed) libcxx/include/__algorithm/pstl_transform.h (-122) 
- (renamed) libcxx/include/__numeric/pstl.h (+81-3) 
- (removed) libcxx/include/__numeric/pstl_reduce.h (-112) 
- (modified) libcxx/include/module.modulemap (+4-26) 


``````````diff
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index dc364cc8d0a226..2278290617bd14 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -72,23 +72,8 @@ set(files
   __algorithm/partition_point.h
   __algorithm/pop_heap.h
   __algorithm/prev_permutation.h
-  __algorithm/pstl_any_all_none_of.h
-  __algorithm/pstl_copy.h
-  __algorithm/pstl_count.h
-  __algorithm/pstl_equal.h
-  __algorithm/pstl_fill.h
-  __algorithm/pstl_find.h
-  __algorithm/pstl_for_each.h
   __algorithm/pstl_frontend_dispatch.h
-  __algorithm/pstl_generate.h
-  __algorithm/pstl_is_partitioned.h
-  __algorithm/pstl_merge.h
-  __algorithm/pstl_move.h
-  __algorithm/pstl_replace.h
-  __algorithm/pstl_rotate_copy.h
-  __algorithm/pstl_sort.h
-  __algorithm/pstl_stable_sort.h
-  __algorithm/pstl_transform.h
+  __algorithm/pstl.h
   __algorithm/push_heap.h
   __algorithm/ranges_adjacent_find.h
   __algorithm/ranges_all_of.h
@@ -573,8 +558,7 @@ set(files
   __numeric/iota.h
   __numeric/midpoint.h
   __numeric/partial_sum.h
-  __numeric/pstl_reduce.h
-  __numeric/pstl_transform_reduce.h
+  __numeric/pstl.h
   __numeric/reduce.h
   __numeric/saturation_arithmetic.h
   __numeric/transform_exclusive_scan.h
diff --git a/libcxx/include/__algorithm/pstl.h b/libcxx/include/__algorithm/pstl.h
new file mode 100644
index 00000000000000..748237def0dbc4
--- /dev/null
+++ b/libcxx/include/__algorithm/pstl.h
@@ -0,0 +1,1353 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 _LIBCPP___ALGORITHM_PSTL_H
+#define _LIBCPP___ALGORITHM_PSTL_H
+
+#include <__algorithm/copy_n.h>
+#include <__algorithm/count.h>
+#include <__algorithm/for_each.h>
+#include <__algorithm/pstl_find.h>
+#include <__algorithm/pstl_for_each.h>
+#include <__algorithm/pstl_frontend_dispatch.h>
+#include <__algorithm/pstl_transform.h>
+#include <__atomic/atomic.h>
+#include <__config>
+#include <__functional/identity.h>
+#include <__functional/operations.h>
+#include <__iterator/concepts.h>
+#include <__iterator/cpp17_iterator_concepts.h>
+#include <__iterator/iterator_traits.h>
+#include <__numeric/pstl_transform_reduce.h>
+#include <__pstl/configuration.h>
+#include <__type_traits/enable_if.h>
+#include <__type_traits/is_constant_evaluated.h>
+#include <__type_traits/is_execution_policy.h>
+#include <__type_traits/is_trivially_copyable.h>
+#include <__type_traits/remove_cvref.h>
+#include <__utility/move.h>
+#include <optional>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class>
+void __pstl_any_of(); // declaration needed for the frontend dispatch below
+
+template <class _ExecutionPolicy,
+          class _ForwardIterator,
+          class _Predicate,
+          class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
+          enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<bool> __any_of(
+    _ExecutionPolicy&& __policy, _ForwardIterator&& __first, _ForwardIterator&& __last, _Predicate&& __pred) noexcept {
+  return std::__pstl_frontend_dispatch(
+      _LIBCPP_PSTL_CUSTOMIZATION_POINT(__pstl_any_of, _RawPolicy),
+      [&](_ForwardIterator __g_first, _ForwardIterator __g_last, _Predicate __g_pred) -> optional<bool> {
+        auto __res = std::__find_if(__policy, __g_first, __g_last, __g_pred);
+        if (!__res)
+          return nullopt;
+        return *__res != __g_last;
+      },
+      std::move(__first),
+      std::move(__last),
+      std::move(__pred));
+}
+
+template <class _ExecutionPolicy,
+          class _ForwardIterator,
+          class _Predicate,
+          class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
+          enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
+_LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI bool
+any_of(_ExecutionPolicy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Predicate __pred) {
+  _LIBCPP_REQUIRE_CPP17_FORWARD_ITERATOR(_ForwardIterator, "any_of requires a ForwardIterator");
+  auto __res = std::__any_of(__policy, std::move(__first), std::move(__last), std::move(__pred));
+  if (!__res)
+    std::__throw_bad_alloc();
+  return *std::move(__res);
+}
+
+template <class>
+void __pstl_all_of(); // declaration needed for the frontend dispatch below
+
+template <class _ExecutionPolicy,
+          class _ForwardIterator,
+          class _Pred,
+          class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
+          enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<bool>
+__all_of(_ExecutionPolicy&& __policy, _ForwardIterator&& __first, _ForwardIterator&& __last, _Pred&& __pred) noexcept {
+  return std::__pstl_frontend_dispatch(
+      _LIBCPP_PSTL_CUSTOMIZATION_POINT(__pstl_all_of, _RawPolicy),
+      [&](_ForwardIterator __g_first, _ForwardIterator __g_last, _Pred __g_pred) -> optional<bool> {
+        auto __res = std::__any_of(__policy, __g_first, __g_last, [&](__iter_reference<_ForwardIterator> __value) {
+          return !__g_pred(__value);
+        });
+        if (!__res)
+          return nullopt;
+        return !*__res;
+      },
+      std::move(__first),
+      std::move(__last),
+      std::move(__pred));
+}
+
+template <class _ExecutionPolicy,
+          class _ForwardIterator,
+          class _Pred,
+          class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
+          enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
+_LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI bool
+all_of(_ExecutionPolicy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Pred __pred) {
+  _LIBCPP_REQUIRE_CPP17_FORWARD_ITERATOR(_ForwardIterator, "all_of requires a ForwardIterator");
+  auto __res = std::__all_of(__policy, std::move(__first), std::move(__last), std::move(__pred));
+  if (!__res)
+    std::__throw_bad_alloc();
+  return *std::move(__res);
+}
+
+template <class>
+void __pstl_none_of(); // declaration needed for the frontend dispatch below
+
+template <class _ExecutionPolicy,
+          class _ForwardIterator,
+          class _Pred,
+          class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
+          enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<bool>
+__none_of(_ExecutionPolicy&& __policy, _ForwardIterator&& __first, _ForwardIterator&& __last, _Pred&& __pred) noexcept {
+  return std::__pstl_frontend_dispatch(
+      _LIBCPP_PSTL_CUSTOMIZATION_POINT(__pstl_none_of, _RawPolicy),
+      [&](_ForwardIterator __g_first, _ForwardIterator __g_last, _Pred __g_pred) -> optional<bool> {
+        auto __res = std::__any_of(__policy, __g_first, __g_last, __g_pred);
+        if (!__res)
+          return nullopt;
+        return !*__res;
+      },
+      std::move(__first),
+      std::move(__last),
+      std::move(__pred));
+}
+
+template <class _ExecutionPolicy,
+          class _ForwardIterator,
+          class _Pred,
+          class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
+          enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
+_LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI bool
+none_of(_ExecutionPolicy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Pred __pred) {
+  _LIBCPP_REQUIRE_CPP17_FORWARD_ITERATOR(_ForwardIterator, "none_of requires a ForwardIterator");
+  auto __res = std::__none_of(__policy, std::move(__first), std::move(__last), std::move(__pred));
+  if (!__res)
+    std::__throw_bad_alloc();
+  return *std::move(__res);
+}
+
+// TODO: Use the std::copy/move shenanigans to forward to std::memmove
+
+template <class>
+void __pstl_copy();
+
+template <class _ExecutionPolicy,
+          class _ForwardIterator,
+          class _ForwardOutIterator,
+          class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
+          enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<_ForwardOutIterator>
+__copy(_ExecutionPolicy&& __policy,
+       _ForwardIterator&& __first,
+       _ForwardIterator&& __last,
+       _ForwardOutIterator&& __result) noexcept {
+  return std::__pstl_frontend_dispatch(
+      _LIBCPP_PSTL_CUSTOMIZATION_POINT(__pstl_copy, _RawPolicy),
+      [&__policy](_ForwardIterator __g_first, _ForwardIterator __g_last, _ForwardOutIterator __g_result) {
+        return std::__transform(__policy, __g_first, __g_last, __g_result, __identity());
+      },
+      std::move(__first),
+      std::move(__last),
+      std::move(__result));
+}
+
+template <class _ExecutionPolicy,
+          class _ForwardIterator,
+          class _ForwardOutIterator,
+          class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
+          enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
+_LIBCPP_HIDE_FROM_ABI _ForwardOutIterator
+copy(_ExecutionPolicy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _ForwardOutIterator __result) {
+  _LIBCPP_REQUIRE_CPP17_FORWARD_ITERATOR(
+      _ForwardIterator, "copy(first, last, result) requires [first, last) to be ForwardIterators");
+  _LIBCPP_REQUIRE_CPP17_FORWARD_ITERATOR(
+      _ForwardOutIterator, "copy(first, last, result) requires result to be a ForwardIterator");
+  _LIBCPP_REQUIRE_CPP17_OUTPUT_ITERATOR(
+      _ForwardOutIterator, decltype(*__first), "copy(first, last, result) requires result to be an OutputIterator");
+  auto __res = std::__copy(__policy, std::move(__first), std::move(__last), std::move(__result));
+  if (!__res)
+    std::__throw_bad_alloc();
+  return *std::move(__res);
+}
+
+template <class>
+void __pstl_copy_n();
+
+template <class _ExecutionPolicy,
+          class _ForwardIterator,
+          class _ForwardOutIterator,
+          class _Size,
+          class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
+          enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<_ForwardOutIterator> __copy_n(
+    _ExecutionPolicy&& __policy, _ForwardIterator&& __first, _Size&& __n, _ForwardOutIterator&& __result) noexcept {
+  return std::__pstl_frontend_dispatch(
+      _LIBCPP_PSTL_CUSTOMIZATION_POINT(__pstl_copy_n, _RawPolicy),
+      [&__policy](
+          _ForwardIterator __g_first, _Size __g_n, _ForwardOutIterator __g_result) -> optional<_ForwardIterator> {
+        if constexpr (__has_random_access_iterator_category_or_concept<_ForwardIterator>::value)
+          return std::__copy(__policy, std::move(__g_first), std::move(__g_first + __g_n), std::move(__g_result));
+        else
+          return std::copy_n(__g_first, __g_n, __g_result);
+      },
+      std::move(__first),
+      std::move(__n),
+      std::move(__result));
+}
+
+template <class _ExecutionPolicy,
+          class _ForwardIterator,
+          class _ForwardOutIterator,
+          class _Size,
+          class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
+          enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
+_LIBCPP_HIDE_FROM_ABI _ForwardOutIterator
+copy_n(_ExecutionPolicy&& __policy, _ForwardIterator __first, _Size __n, _ForwardOutIterator __result) {
+  _LIBCPP_REQUIRE_CPP17_FORWARD_ITERATOR(
+      _ForwardIterator, "copy_n(first, n, result) requires first to be a ForwardIterator");
+  _LIBCPP_REQUIRE_CPP17_FORWARD_ITERATOR(
+      _ForwardOutIterator, "copy_n(first, n, result) requires result to be a ForwardIterator");
+  _LIBCPP_REQUIRE_CPP17_OUTPUT_ITERATOR(
+      _ForwardOutIterator, decltype(*__first), "copy_n(first, n, result) requires result to be an OutputIterator");
+  auto __res = std::__copy_n(__policy, std::move(__first), std::move(__n), std::move(__result));
+  if (!__res)
+    std::__throw_bad_alloc();
+  return *std::move(__res);
+}
+
+template <class>
+void __pstl_count_if(); // declaration needed for the frontend dispatch below
+
+template <class _ExecutionPolicy,
+          class _ForwardIterator,
+          class _Predicate,
+          class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
+          enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<__iter_diff_t<_ForwardIterator>> __count_if(
+    _ExecutionPolicy&& __policy, _ForwardIterator&& __first, _ForwardIterator&& __last, _Predicate&& __pred) noexcept {
+  using __diff_t = __iter_diff_t<_ForwardIterator>;
+  return std::__pstl_frontend_dispatch(
+      _LIBCPP_PSTL_CUSTOMIZATION_POINT(__pstl_count_if, _RawPolicy),
+      [&](_ForwardIterator __g_first, _ForwardIterator __g_last, _Predicate __g_pred) -> optional<__diff_t> {
+        return std::__transform_reduce(
+            __policy,
+            std::move(__g_first),
+            std::move(__g_last),
+            __diff_t(),
+            std::plus{},
+            [&](__iter_reference<_ForwardIterator> __element) -> bool { return __g_pred(__element); });
+      },
+      std::move(__first),
+      std::move(__last),
+      std::move(__pred));
+}
+
+template <class _ExecutionPolicy,
+          class _ForwardIterator,
+          class _Predicate,
+          class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
+          enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
+_LIBCPP_HIDE_FROM_ABI __iter_diff_t<_ForwardIterator>
+count_if(_ExecutionPolicy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Predicate __pred) {
+  _LIBCPP_REQUIRE_CPP17_FORWARD_ITERATOR(
+      _ForwardIterator, "count_if(first, last, pred) requires [first, last) to be ForwardIterators");
+  auto __res = std::__count_if(__policy, std::move(__first), std::move(__last), std::move(__pred));
+  if (!__res)
+    std::__throw_bad_alloc();
+  return *std::move(__res);
+}
+
+template <class>
+void __pstl_count(); // declaration needed for the frontend dispatch below
+
+template <class _ExecutionPolicy,
+          class _ForwardIterator,
+          class _Tp,
+          class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
+          enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<__iter_diff_t<_ForwardIterator>>
+__count(_ExecutionPolicy&& __policy, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value) {
+  return std::__pstl_frontend_dispatch(
+      _LIBCPP_PSTL_CUSTOMIZATION_POINT(__pstl_count, _RawPolicy),
+      [&](_ForwardIterator __g_first, _ForwardIterator __g_last, const _Tp& __g_value)
+          -> optional<__iter_diff_t<_ForwardIterator>> {
+        return std::count_if(__policy, __g_first, __g_last, [&](__iter_reference<_ForwardIterator> __v) {
+          return __v == __g_value;
+        });
+      },
+      std::move(__first),
+      std::move(__last),
+      __value);
+}
+
+template <class _ExecutionPolicy,
+          class _ForwardIterator,
+          class _Tp,
+          class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
+          enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
+_LIBCPP_HIDE_FROM_ABI __iter_diff_t<_ForwardIterator>
+count(_ExecutionPolicy&& __policy, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value) {
+  _LIBCPP_REQUIRE_CPP17_FORWARD_ITERATOR(
+      _ForwardIterator, "count(first, last, val) requires [first, last) to be ForwardIterators");
+  auto __res = std::__count(__policy, std::move(__first), std::move(__last), __value);
+  if (!__res)
+    std::__throw_bad_alloc();
+  return *__res;
+}
+
+template <class>
+void __pstl_equal();
+
+template <class _ExecutionPolicy,
+          class _ForwardIterator1,
+          class _ForwardIterator2,
+          class _Pred,
+          class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
+          enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<bool>
+__equal(_ExecutionPolicy&& __policy,
+        _ForwardIterator1&& __first1,
+        _ForwardIterator1&& __last1,
+        _ForwardIterator2&& __first2,
+        _Pred&& __pred) noexcept {
+  return std::__pstl_frontend_dispatch(
+      _LIBCPP_PSTL_CUSTOMIZATION_POINT(__pstl_equal, _RawPolicy),
+      [&__policy](
+          _ForwardIterator1 __g_first1, _ForwardIterator1 __g_last1, _ForwardIterator2 __g_first2, _Pred __g_pred) {
+        return std::__transform_reduce(
+            __policy,
+            std::move(__g_first1),
+            std::move(__g_last1),
+            std::move(__g_first2),
+            true,
+            std::logical_and{},
+            std::move(__g_pred));
+      },
+      std::move(__first1),
+      std::move(__last1),
+      std::move(__first2),
+      std::move(__pred));
+}
+
+template <class _ExecutionPolicy,
+          class _ForwardIterator1,
+          class _ForwardIterator2,
+          class _Pred,
+          class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
+          enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
+_LIBCPP_HIDE_FROM_ABI bool
+equal(_ExecutionPolicy&& __policy,
+      _ForwardIterator1 __first1,
+      _ForwardIterator1 __last1,
+      _ForwardIterator2 __first2,
+      _Pred __pred) {
+  _LIBCPP_REQUIRE_CPP17_FORWARD_ITERATOR(_ForwardIterator1, "equal requires ForwardIterators");
+  _LIBCPP_REQUIRE_CPP17_FORWARD_ITERATOR(_ForwardIterator2, "equal requires ForwardIterators");
+  auto __res = std::__equal(__policy, std::move(__first1), std::move(__last1), std::move(__first2), std::move(__pred));
+  if (!__res)
+    std::__throw_bad_alloc();
+  return *__res;
+}
+
+template <class _ExecutionPolicy,
+          class _ForwardIterator1,
+          class _ForwardIterator2,
+          enable_if_t<is_execution_policy_v<__remove_cvref_t<_ExecutionPolicy>>, int> = 0>
+_LIBCPP_HIDE_FROM_ABI bool
+equal(_ExecutionPolicy&& __policy, _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2) {
+  _LIBCPP_REQUIRE_CPP17_FORWARD_ITERATOR(_ForwardIterator1, "equal requires ForwardIterators");
+  _LIBCPP_REQUIRE_CPP17_FORWARD_ITERATOR(_ForwardIterator2, "equal requires ForwardIterators");
+  return std::equal(__policy, std::move(__first1), std::move(__last1), std::move(__first2), std::equal_to{});
+}
+
+template <class _ExecutionPolicy,
+          class _ForwardIterator1,
+          class _ForwardIterator2,
+          class _Pred,
+          class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
+          enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<bool>
+__equal(_ExecutionPolicy&& __policy,
+        _ForwardIterator1&& __first1,
+        _ForwardIterator1&& __last1,
+        _ForwardIterator2&& __first2,
+        _ForwardIterator2&& __last2,
+        _Pred&& __pred) noexcept {
+  return std::__pstl_frontend_dispatch(
+      _LIBCPP_PSTL_CUSTOMIZATION_POINT(__pstl_equal, _RawPolicy),
+      [&__policy](_ForwardIterator1 __g_first1,
+                  _ForwardIterator1 __g_last1,
+                  _ForwardIterator2 __g_first2,
+                  _ForwardIterator2 __g_last2,
+                  _Pred __g_pred) -> optional<bool> {
+        if constexpr (__has_random_access_iterator_category<_ForwardIterator1>::value &&
+                      __has_random_access_iterator_category<_ForwardIterator2>::value) {
+          if (__g_last1 - __g_first1 != __g_last2 - __g_first2)
+            return false;
+          return std::__equal(
+              __policy, std::move(__g_first1), std::move(__g_last1), std::move(__g_first2), std::move(__g_pred));
+        } else {
+          (void)__policy; // Avoid unused lambda capture warning
...
[truncated]

``````````

</details>


https://github.com/llvm/llvm-project/pull/89219


More information about the libcxx-commits mailing list