libcxx/include/__pstl/cpu_algos/for_each.h

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef _LIBCPP___PSTL_CPU_ALGOS_FOR_EACH_H
  10 #define _LIBCPP___PSTL_CPU_ALGOS_FOR_EACH_H
  11
  12 #include <__algorithm/for_each.h>
  13 #include <__assert>
  14 #include <__config>
  15 #include <__iterator/concepts.h>
  16 #include <__pstl/backend_fwd.h>
  17 #include <__pstl/cpu_algos/cpu_traits.h>
  18 #include <__type_traits/is_execution_policy.h>
  19 #include <__utility/empty.h>
  20 #include <optional>
  21
  22 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  23 #  pragma GCC system_header
  24 #endif
  25
  26 #if _LIBCPP_STD_VER >= 17
  27
  28 _LIBCPP_BEGIN_NAMESPACE_STD
  29 namespace __pstl {
  30
  31 template <class _Iterator, class _DifferenceType, class _Function>
  32 _LIBCPP_HIDE_FROM_ABI _Iterator __simd_for_each(_Iterator __first, _DifferenceType __n, _Function __f) noexcept {
  33   _PSTL_PRAGMA_SIMD
  34   for (_DifferenceType __i = 0; __i < __n; ++__i)
  35     __f(__first[__i]);
  36
  37   return __first + __n;
  38 }
  39
  40 template <class _Backend, class _RawExecutionPolicy>
  41 struct __cpu_parallel_for_each {
  42   template <class _Policy, class _ForwardIterator, class _Function>
  43   _LIBCPP_HIDE_FROM_ABI optional<__empty>
  44   operator()(_Policy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Function __func) const noexcept {
  45     if constexpr (__is_parallel_execution_policy_v<_RawExecutionPolicy> &&
  46                   __has_random_access_iterator_category_or_concept<_ForwardIterator>::value) {
  47       return __cpu_traits<_Backend>::__for_each(
  48           __first, __last, [&__policy, __func](_ForwardIterator __brick_first, _ForwardIterator __brick_last) {
  49             using _ForEachUnseq = __pstl::__for_each<_Backend, __remove_parallel_policy_t<_RawExecutionPolicy>>;
  50             [[maybe_unused]] auto __res =
  51                 _ForEachUnseq()(std::__remove_parallel_policy(__policy), __brick_first, __brick_last, __func);
  52             _LIBCPP_ASSERT_INTERNAL(__res, "unseq/seq should never try to allocate!");
  53           });
  54     } else if constexpr (__is_unsequenced_execution_policy_v<_RawExecutionPolicy> &&
  55                          __has_random_access_iterator_category_or_concept<_ForwardIterator>::value) {
  56       __pstl::__simd_for_each(__first, __last - __first, __func);
  57       return __empty{};
  58     } else {
  59       std::for_each(__first, __last, __func);
  60       return __empty{};
  61     }
  62   }
  63 };
  64
  65 } // namespace __pstl
  66 _LIBCPP_END_NAMESPACE_STD
  67
  68 #endif // _LIBCPP_STD_VER >= 17
  69
  70 #endif // _LIBCPP___PSTL_CPU_ALGOS_FOR_EACH_H