[libcxx-commits] [libcxx] [libcxx] Unifying __is_trivial_equality_predicate and __is_trivial_plus_operation into __desugars_to (PR #68642)

Anton Rydahl via libcxx-commits libcxx-commits at lists.llvm.org
Mon Oct 9 15:40:58 PDT 2023


https://github.com/AntonRydahl created https://github.com/llvm/llvm-project/pull/68642

When working on an OpenMP offloading backend for standard parallel algorithms (https://github.com/llvm/llvm-project/pull/66968) we noticed the need of a generalization of `__is_trivial_plus_operation`. For now, I have converted `__is_trivial_equality_predicate` and `__is_trivial_plus_operation` into `__desugars_to`, and we may then extend the latter to support other binary operations as well.

>From f0d93cc6a5cd485c654ab38221691db038bacc7d Mon Sep 17 00:00:00 2001
From: AntonRydahl <rydahl2610 at gmail.com>
Date: Mon, 9 Oct 2023 15:13:22 -0700
Subject: [PATCH] Merged __is_trivial_equality_predicate and
 __is_trivial_plus_operation into __desugars_to

---
 libcxx/include/CMakeLists.txt                 |  1 -
 libcxx/include/__algorithm/comp.h             |  7 ++---
 libcxx/include/__algorithm/equal.h            | 22 ++++++++--------
 .../cpu_backends/transform_reduce.h           | 23 ++++++++--------
 libcxx/include/__functional/operations.h      | 15 +++++------
 .../include/__functional/ranges_operations.h  |  7 ++---
 .../include/__numeric/pstl_transform_reduce.h |  2 +-
 .../include/__type_traits/operation_traits.h  |  4 +--
 .../include/__type_traits/predicate_traits.h  | 26 -------------------
 libcxx/include/module.modulemap.in            |  1 -
 10 files changed, 40 insertions(+), 68 deletions(-)
 delete mode 100644 libcxx/include/__type_traits/predicate_traits.h

diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index 340353f8ebb41c4..7eb09a06ccd482e 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -813,7 +813,6 @@ set(files
   __type_traits/negation.h
   __type_traits/noexcept_move_assign_container.h
   __type_traits/operation_traits.h
-  __type_traits/predicate_traits.h
   __type_traits/promote.h
   __type_traits/rank.h
   __type_traits/remove_all_extents.h
diff --git a/libcxx/include/__algorithm/comp.h b/libcxx/include/__algorithm/comp.h
index 9474536615ffb67..0993c37cce36a6b 100644
--- a/libcxx/include/__algorithm/comp.h
+++ b/libcxx/include/__algorithm/comp.h
@@ -10,8 +10,9 @@
 #define _LIBCPP___ALGORITHM_COMP_H
 
 #include <__config>
+#include <__functional/operations.h>
 #include <__type_traits/integral_constant.h>
-#include <__type_traits/predicate_traits.h>
+#include <__type_traits/operation_traits.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
@@ -26,8 +27,8 @@ struct __equal_to {
   }
 };
 
-template <class _Lhs, class _Rhs>
-struct __is_trivial_equality_predicate<__equal_to, _Lhs, _Rhs> : true_type {};
+template <>
+struct __desugars_to<__equal_to, std::equal_to<>> : true_type {};
 
 // The definition is required because __less is part of the ABI, but it's empty
 // because all comparisons should be transparent.
diff --git a/libcxx/include/__algorithm/equal.h b/libcxx/include/__algorithm/equal.h
index b69aeff92bb9289..35e82da15e4d058 100644
--- a/libcxx/include/__algorithm/equal.h
+++ b/libcxx/include/__algorithm/equal.h
@@ -15,6 +15,7 @@
 #include <__config>
 #include <__functional/identity.h>
 #include <__functional/invoke.h>
+#include <__functional/operations.h>
 #include <__iterator/distance.h>
 #include <__iterator/iterator_traits.h>
 #include <__string/constexpr_c_functions.h>
@@ -23,7 +24,7 @@
 #include <__type_traits/is_constant_evaluated.h>
 #include <__type_traits/is_equality_comparable.h>
 #include <__type_traits/is_volatile.h>
-#include <__type_traits/predicate_traits.h>
+#include <__type_traits/operation_traits.h>
 #include <__utility/move.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -41,13 +42,12 @@ _LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 boo
   return true;
 }
 
-template <
-    class _Tp,
-    class _Up,
-    class _BinaryPredicate,
-    __enable_if_t<__is_trivial_equality_predicate<_BinaryPredicate, _Tp, _Up>::value && !is_volatile<_Tp>::value &&
-                      !is_volatile<_Up>::value && __libcpp_is_trivially_equality_comparable<_Tp, _Up>::value,
-                  int> = 0>
+template < class _Tp,
+           class _Up,
+           class _BinaryPredicate,
+           __enable_if_t<__desugars_to<_BinaryPredicate, std::equal_to<>>::value && !is_volatile<_Tp>::value &&
+                             !is_volatile<_Up>::value && __libcpp_is_trivially_equality_comparable<_Tp, _Up>::value,
+                         int> = 0>
 _LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool
 __equal_iter_impl(_Tp* __first1, _Tp* __last1, _Up* __first2, _BinaryPredicate&) {
   return std::__constexpr_memcmp_equal(__first1, __first2, __element_count(__last1 - __first1));
@@ -94,12 +94,12 @@ template <class _Tp,
           class _Pred,
           class _Proj1,
           class _Proj2,
-          __enable_if_t<__is_trivial_equality_predicate<_Pred, _Tp, _Up>::value && __is_identity<_Proj1>::value &&
+          __enable_if_t<__desugars_to<_Pred, std::equal_to<>>::value && __is_identity<_Proj1>::value &&
                             __is_identity<_Proj2>::value && !is_volatile<_Tp>::value && !is_volatile<_Up>::value &&
                             __libcpp_is_trivially_equality_comparable<_Tp, _Up>::value,
                         int> = 0>
-_LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __equal_impl(
-    _Tp* __first1, _Tp* __last1, _Up* __first2, _Up*, _Pred&, _Proj1&, _Proj2&) {
+_LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool
+__equal_impl(_Tp* __first1, _Tp* __last1, _Up* __first2, _Up*, _Pred&, _Proj1&, _Proj2&) {
   return std::__constexpr_memcmp_equal(__first1, __first2, __element_count(__last1 - __first1));
 }
 
diff --git a/libcxx/include/__algorithm/pstl_backends/cpu_backends/transform_reduce.h b/libcxx/include/__algorithm/pstl_backends/cpu_backends/transform_reduce.h
index a5ca9c89d1ab23b..3f4bc31632956b3 100644
--- a/libcxx/include/__algorithm/pstl_backends/cpu_backends/transform_reduce.h
+++ b/libcxx/include/__algorithm/pstl_backends/cpu_backends/transform_reduce.h
@@ -11,6 +11,7 @@
 
 #include <__algorithm/pstl_backends/cpu_backends/backend.h>
 #include <__config>
+#include <__functional/operations.h>
 #include <__iterator/concepts.h>
 #include <__iterator/iterator_traits.h>
 #include <__numeric/transform_reduce.h>
@@ -29,12 +30,11 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-template <
-    typename _DifferenceType,
-    typename _Tp,
-    typename _BinaryOperation,
-    typename _UnaryOperation,
-    __enable_if_t<__is_trivial_plus_operation<_BinaryOperation, _Tp, _Tp>::value && is_arithmetic_v<_Tp>, int> = 0>
+template < typename _DifferenceType,
+           typename _Tp,
+           typename _BinaryOperation,
+           typename _UnaryOperation,
+           __enable_if_t<__desugars_to<_BinaryOperation, std::plus<>>::value && is_arithmetic_v<_Tp>, int> = 0>
 _LIBCPP_HIDE_FROM_ABI _Tp
 __simd_transform_reduce(_DifferenceType __n, _Tp __init, _BinaryOperation, _UnaryOperation __f) noexcept {
   _PSTL_PRAGMA_SIMD_REDUCTION(+ : __init)
@@ -43,12 +43,11 @@ __simd_transform_reduce(_DifferenceType __n, _Tp __init, _BinaryOperation, _Unar
   return __init;
 }
 
-template <
-    typename _Size,
-    typename _Tp,
-    typename _BinaryOperation,
-    typename _UnaryOperation,
-    __enable_if_t<!(__is_trivial_plus_operation<_BinaryOperation, _Tp, _Tp>::value && is_arithmetic_v<_Tp>), int> = 0>
+template < typename _Size,
+           typename _Tp,
+           typename _BinaryOperation,
+           typename _UnaryOperation,
+           __enable_if_t<!(__desugars_to<_BinaryOperation, std::plus<>>::value && is_arithmetic_v<_Tp>), int> = 0>
 _LIBCPP_HIDE_FROM_ABI _Tp
 __simd_transform_reduce(_Size __n, _Tp __init, _BinaryOperation __binary_op, _UnaryOperation __f) noexcept {
   const _Size __block_size = __lane_size / sizeof(_Tp);
diff --git a/libcxx/include/__functional/operations.h b/libcxx/include/__functional/operations.h
index 6cdb89d6b449bcd..d6c8ff547cfbdcd 100644
--- a/libcxx/include/__functional/operations.h
+++ b/libcxx/include/__functional/operations.h
@@ -15,7 +15,6 @@
 #include <__functional/unary_function.h>
 #include <__type_traits/integral_constant.h>
 #include <__type_traits/operation_traits.h>
-#include <__type_traits/predicate_traits.h>
 #include <__utility/forward.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -41,12 +40,12 @@ struct _LIBCPP_TEMPLATE_VIS plus
 };
 _LIBCPP_CTAD_SUPPORTED_FOR_TYPE(plus);
 
-template <class _Tp>
-struct __is_trivial_plus_operation<plus<_Tp>, _Tp, _Tp> : true_type {};
+template <class _Pred>
+struct __desugars_to<plus<_Pred>, plus<_Pred>> : true_type {};
 
 #if _LIBCPP_STD_VER >= 14
-template <class _Tp, class _Up>
-struct __is_trivial_plus_operation<plus<>, _Tp, _Up> : true_type {};
+template <>
+struct __desugars_to<plus<>, plus<>> : true_type {};
 #endif
 
 #if _LIBCPP_STD_VER >= 14
@@ -353,11 +352,11 @@ struct _LIBCPP_TEMPLATE_VIS equal_to<void>
 #endif
 
 template <class _Tp>
-struct __is_trivial_equality_predicate<equal_to<_Tp>, _Tp, _Tp> : true_type {};
+struct __desugars_to<equal_to<_Tp>, std::equal_to<_Tp>> : true_type {};
 
 #if _LIBCPP_STD_VER >= 14
-template <class _Tp>
-struct __is_trivial_equality_predicate<equal_to<>, _Tp, _Tp> : true_type {};
+template <>
+struct __desugars_to<equal_to<>, std::equal_to<>> : true_type {};
 #endif
 
 #if _LIBCPP_STD_VER >= 14
diff --git a/libcxx/include/__functional/ranges_operations.h b/libcxx/include/__functional/ranges_operations.h
index c344fc38f98ddd9..22d6f7fef3b3da5 100644
--- a/libcxx/include/__functional/ranges_operations.h
+++ b/libcxx/include/__functional/ranges_operations.h
@@ -13,8 +13,9 @@
 #include <__concepts/equality_comparable.h>
 #include <__concepts/totally_ordered.h>
 #include <__config>
+#include <__functional/operations.h>
 #include <__type_traits/integral_constant.h>
-#include <__type_traits/predicate_traits.h>
+#include <__type_traits/operation_traits.h>
 #include <__utility/forward.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -95,8 +96,8 @@ struct greater_equal {
 
 } // namespace ranges
 
-template <class _Lhs, class _Rhs>
-struct __is_trivial_equality_predicate<ranges::equal_to, _Lhs, _Rhs> : true_type {};
+template <>
+struct __desugars_to<ranges::equal_to, std::equal_to<>> : true_type {};
 
 #endif // _LIBCPP_STD_VER >= 20
 
diff --git a/libcxx/include/__numeric/pstl_transform_reduce.h b/libcxx/include/__numeric/pstl_transform_reduce.h
index 4127ee21e3045c8..1127726046665c0 100644
--- a/libcxx/include/__numeric/pstl_transform_reduce.h
+++ b/libcxx/include/__numeric/pstl_transform_reduce.h
@@ -84,7 +84,7 @@ _LIBCPP_HIDE_FROM_ABI _Tp transform_reduce(
 }
 
 // This overload doesn't get a customization point because it's trivial to detect (through e.g.
-// __is_trivial_plus_operation) when specializing the more general variant, which should always be preferred
+// __desugars_to) when specializing the more general variant, which should always be preferred
 template <class _ExecutionPolicy,
           class _ForwardIterator1,
           class _ForwardIterator2,
diff --git a/libcxx/include/__type_traits/operation_traits.h b/libcxx/include/__type_traits/operation_traits.h
index 7dda93e9083a404..d03bf6209a6cc77 100644
--- a/libcxx/include/__type_traits/operation_traits.h
+++ b/libcxx/include/__type_traits/operation_traits.h
@@ -18,8 +18,8 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-template <class _Pred, class _Lhs, class _Rhs>
-struct __is_trivial_plus_operation : false_type {};
+template <class _Pred, class _Reference>
+struct __desugars_to : false_type {};
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/__type_traits/predicate_traits.h b/libcxx/include/__type_traits/predicate_traits.h
deleted file mode 100644
index 872608e6ac3be3f..000000000000000
--- a/libcxx/include/__type_traits/predicate_traits.h
+++ /dev/null
@@ -1,26 +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 _LIBCPP___TYPE_TRAITS_PREDICATE_TRAITS
-#define _LIBCPP___TYPE_TRAITS_PREDICATE_TRAITS
-
-#include <__config>
-#include <__type_traits/integral_constant.h>
-
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#  pragma GCC system_header
-#endif
-
-_LIBCPP_BEGIN_NAMESPACE_STD
-
-template <class _Pred, class _Lhs, class _Rhs>
-struct __is_trivial_equality_predicate : false_type {};
-
-_LIBCPP_END_NAMESPACE_STD
-
-#endif // _LIBCPP___TYPE_TRAITS_PREDICATE_TRAITS
diff --git a/libcxx/include/module.modulemap.in b/libcxx/include/module.modulemap.in
index 26657b78b8440c6..3c08c2fb52ce65f 100644
--- a/libcxx/include/module.modulemap.in
+++ b/libcxx/include/module.modulemap.in
@@ -2015,7 +2015,6 @@ module std_private_type_traits_nat                                       [system
 module std_private_type_traits_negation                                  [system] { header "__type_traits/negation.h" }
 module std_private_type_traits_noexcept_move_assign_container            [system] { header "__type_traits/noexcept_move_assign_container.h" }
 module std_private_type_traits_operation_traits                          [system] { header "__type_traits/operation_traits.h" }
-module std_private_type_traits_predicate_traits                          [system] { header "__type_traits/predicate_traits.h" }
 module std_private_type_traits_promote                                   [system] { header "__type_traits/promote.h" }
 module std_private_type_traits_rank                                      [system] { header "__type_traits/rank.h" }
 module std_private_type_traits_remove_all_extents                        [system] { header "__type_traits/remove_all_extents.h" }



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