libcxx/include/__algorithm/pstl_backends/cpu_backends/fill.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___ALGORITHM_PSTL_BACKENDS_CPU_BACKENDS_FILL_H
  10 #define _LIBCPP___ALGORITHM_PSTL_BACKENDS_CPU_BACKENDS_FILL_H
  11
  12 #include <__algorithm/fill.h>
  13 #include <__algorithm/pstl_backends/cpu_backends/backend.h>
  14 #include <__config>
  15 #include <__iterator/concepts.h>
  16 #include <__type_traits/is_execution_policy.h>
  17 #include <__utility/empty.h>
  18 #include <optional>
  19
  20 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  21 #  pragma GCC system_header
  22 #endif
  23
  24 #if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
  25
  26 _LIBCPP_BEGIN_NAMESPACE_STD
  27
  28 template <class _Index, class _DifferenceType, class _Tp>
  29 _LIBCPP_HIDE_FROM_ABI _Index __simd_fill_n(_Index __first, _DifferenceType __n, const _Tp& __value) noexcept {
  30   _PSTL_USE_NONTEMPORAL_STORES_IF_ALLOWED
  31   _PSTL_PRAGMA_SIMD
  32   for (_DifferenceType __i = 0; __i < __n; ++__i)
  33     __first[__i] = __value;
  34   return __first + __n;
  35 }
  36
  37 template <class _ExecutionPolicy, class _ForwardIterator, class _Tp>
  38 _LIBCPP_HIDE_FROM_ABI optional<__empty>
  39 __pstl_fill(__cpu_backend_tag, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value) {
  40   if constexpr (__is_parallel_execution_policy_v<_ExecutionPolicy> &&
  41                 __has_random_access_iterator_category_or_concept<_ForwardIterator>::value) {
  42     return __par_backend::__parallel_for(
  43         __first, __last, [&__value](_ForwardIterator __brick_first, _ForwardIterator __brick_last) {
  44           [[maybe_unused]] auto __res = std::__pstl_fill<__remove_parallel_policy_t<_ExecutionPolicy>>(
  45               __cpu_backend_tag{}, __brick_first, __brick_last, __value);
  46           _LIBCPP_ASSERT_INTERNAL(__res, "unseq/seq should never try to allocate!");
  47         });
  48   } else if constexpr (__is_unsequenced_execution_policy_v<_ExecutionPolicy> &&
  49                        __has_random_access_iterator_category_or_concept<_ForwardIterator>::value) {
  50     std::__simd_fill_n(__first, __last - __first, __value);
  51     return __empty{};
  52   } else {
  53     std::fill(__first, __last, __value);
  54     return __empty{};
  55   }
  56 }
  57
  58 _LIBCPP_END_NAMESPACE_STD
  59
  60 #endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
  61
  62 #endif // _LIBCPP___ALGORITHM_PSTL_BACKENDS_CPU_BACKENDS_FILL_H