__pstl/cpu_algos/for_each.h

0001 //===----------------------------------------------------------------------===//
0002 //
0003 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0004 // See https://llvm.org/LICENSE.txt for license information.
0005 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0006 //
0007 //===----------------------------------------------------------------------===//
0008
0009 #ifndef _LIBCPP___PSTL_CPU_ALGOS_FOR_EACH_H
0010 #define _LIBCPP___PSTL_CPU_ALGOS_FOR_EACH_H
0011
0012 #include <__algorithm/for_each.h>
0013 #include <__assert>
0014 #include <__config>
0015 #include <__iterator/concepts.h>
0016 #include <__pstl/backend_fwd.h>
0017 #include <__pstl/cpu_algos/cpu_traits.h>
0018 #include <__type_traits/is_execution_policy.h>
0019 #include <__utility/empty.h>
0020 #include <optional>
0021
0022 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0023 #  pragma GCC system_header
0024 #endif
0025
0026 #if _LIBCPP_STD_VER >= 17
0027
0028 _LIBCPP_BEGIN_NAMESPACE_STD
0029 namespace __pstl {
0030
0031 template <class _Iterator, class _DifferenceType, class _Function>
0032 _LIBCPP_HIDE_FROM_ABI _Iterator __simd_for_each(_Iterator __first, _DifferenceType __n, _Function __f) noexcept {
0033   _PSTL_PRAGMA_SIMD
0034   for (_DifferenceType __i = 0; __i < __n; ++__i)
0035     __f(__first[__i]);
0036
0037   return __first + __n;
0038 }
0039
0040 template <class _Backend, class _RawExecutionPolicy>
0041 struct __cpu_parallel_for_each {
0042   template <class _Policy, class _ForwardIterator, class _Function>
0043   _LIBCPP_HIDE_FROM_ABI optional<__empty>
0044   operator()(_Policy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Function __func) const noexcept {
0045     if constexpr (__is_parallel_execution_policy_v<_RawExecutionPolicy> &&
0046                   __has_random_access_iterator_category_or_concept<_ForwardIterator>::value) {
0047       return __cpu_traits<_Backend>::__for_each(
0048           __first, __last, [&__policy, __func](_ForwardIterator __brick_first, _ForwardIterator __brick_last) {
0049             using _ForEachUnseq = __pstl::__for_each<_Backend, __remove_parallel_policy_t<_RawExecutionPolicy>>;
0050             [[maybe_unused]] auto __res =
0051                 _ForEachUnseq()(std::__remove_parallel_policy(__policy), __brick_first, __brick_last, __func);
0052             _LIBCPP_ASSERT_INTERNAL(__res, "unseq/seq should never try to allocate!");
0053           });
0054     } else if constexpr (__is_unsequenced_execution_policy_v<_RawExecutionPolicy> &&
0055                          __has_random_access_iterator_category_or_concept<_ForwardIterator>::value) {
0056       __pstl::__simd_for_each(__first, __last - __first, __func);
0057       return __empty{};
0058     } else {
0059       std::for_each(__first, __last, __func);
0060       return __empty{};
0061     }
0062   }
0063 };
0064
0065 } // namespace __pstl
0066 _LIBCPP_END_NAMESPACE_STD
0067
0068 #endif // _LIBCPP_STD_VER >= 17
0069
0070 #endif // _LIBCPP___PSTL_CPU_ALGOS_FOR_EACH_H