__pstl/cpu_algos/transform.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___CXX03___PSTL_CPU_ALGOS_TRANSFORM_H
0010 #define _LIBCPP___CXX03___PSTL_CPU_ALGOS_TRANSFORM_H
0011
0012 #include <__cxx03/__algorithm/transform.h>
0013 #include <__cxx03/__assert>
0014 #include <__cxx03/__config>
0015 #include <__cxx03/__iterator/concepts.h>
0016 #include <__cxx03/__iterator/iterator_traits.h>
0017 #include <__cxx03/__pstl/backend_fwd.h>
0018 #include <__cxx03/__pstl/cpu_algos/cpu_traits.h>
0019 #include <__cxx03/__type_traits/is_execution_policy.h>
0020 #include <__cxx03/__utility/move.h>
0021 #include <__cxx03/optional>
0022
0023 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0024 #  pragma GCC system_header
0025 #endif
0026
0027 _LIBCPP_PUSH_MACROS
0028 #include <__cxx03/__undef_macros>
0029
0030 _LIBCPP_BEGIN_NAMESPACE_STD
0031 namespace __pstl {
0032
0033 template <class _Iterator1, class _DifferenceType, class _Iterator2, class _Function>
0034 _LIBCPP_HIDE_FROM_ABI _Iterator2
0035 __simd_transform(_Iterator1 __first1, _DifferenceType __n, _Iterator2 __first2, _Function __f) noexcept {
0036   _PSTL_PRAGMA_SIMD
0037   for (_DifferenceType __i = 0; __i < __n; ++__i)
0038     __f(__first1[__i], __first2[__i]);
0039   return __first2 + __n;
0040 }
0041
0042 template <class _Iterator1, class _DifferenceType, class _Iterator2, class _Iterator3, class _Function>
0043 _LIBCPP_HIDE_FROM_ABI _Iterator3 __simd_transform(
0044     _Iterator1 __first1, _DifferenceType __n, _Iterator2 __first2, _Iterator3 __first3, _Function __f) noexcept {
0045   _PSTL_PRAGMA_SIMD
0046   for (_DifferenceType __i = 0; __i < __n; ++__i)
0047     __f(__first1[__i], __first2[__i], __first3[__i]);
0048   return __first3 + __n;
0049 }
0050
0051 template <class _Backend, class _RawExecutionPolicy>
0052 struct __cpu_parallel_transform {
0053   template <class _Policy, class _ForwardIterator, class _ForwardOutIterator, class _UnaryOperation>
0054   _LIBCPP_HIDE_FROM_ABI optional<_ForwardOutIterator>
0055   operator()(_Policy&& __policy,
0056              _ForwardIterator __first,
0057              _ForwardIterator __last,
0058              _ForwardOutIterator __result,
0059              _UnaryOperation __op) const noexcept {
0060     if constexpr (__is_parallel_execution_policy_v<_RawExecutionPolicy> &&
0061                   __has_random_access_iterator_category_or_concept<_ForwardIterator>::value &&
0062                   __has_random_access_iterator_category_or_concept<_ForwardOutIterator>::value) {
0063       __cpu_traits<_Backend>::__for_each(
0064           __first,
0065           __last,
0066           [&__policy, __op, __first, __result](_ForwardIterator __brick_first, _ForwardIterator __brick_last) {
0067             using _TransformUnseq = __pstl::__transform<_Backend, __remove_parallel_policy_t<_RawExecutionPolicy>>;
0068             auto __res            = _TransformUnseq()(
0069                 std::__remove_parallel_policy(__policy),
0070                 __brick_first,
0071                 __brick_last,
0072                 __result + (__brick_first - __first),
0073                 __op);
0074             _LIBCPP_ASSERT_INTERNAL(__res, "unseq/seq should never try to allocate!");
0075             return *std::move(__res);
0076           });
0077       return __result + (__last - __first);
0078     } else if constexpr (__is_unsequenced_execution_policy_v<_RawExecutionPolicy> &&
0079                          __has_random_access_iterator_category_or_concept<_ForwardIterator>::value &&
0080                          __has_random_access_iterator_category_or_concept<_ForwardOutIterator>::value) {
0081       return __pstl::__simd_transform(
0082           __first,
0083           __last - __first,
0084           __result,
0085           [&](__iter_reference<_ForwardIterator> __in_value, __iter_reference<_ForwardOutIterator> __out_value) {
0086             __out_value = __op(__in_value);
0087           });
0088     } else {
0089       return std::transform(__first, __last, __result, __op);
0090     }
0091   }
0092 };
0093
0094 template <class _Backend, class _RawExecutionPolicy>
0095 struct __cpu_parallel_transform_binary {
0096   template <class _Policy,
0097             class _ForwardIterator1,
0098             class _ForwardIterator2,
0099             class _ForwardOutIterator,
0100             class _BinaryOperation>
0101   _LIBCPP_HIDE_FROM_ABI optional<_ForwardOutIterator>
0102   operator()(_Policy&& __policy,
0103              _ForwardIterator1 __first1,
0104              _ForwardIterator1 __last1,
0105              _ForwardIterator2 __first2,
0106              _ForwardOutIterator __result,
0107              _BinaryOperation __op) const noexcept {
0108     if constexpr (__is_parallel_execution_policy_v<_RawExecutionPolicy> &&
0109                   __has_random_access_iterator_category_or_concept<_ForwardIterator1>::value &&
0110                   __has_random_access_iterator_category_or_concept<_ForwardIterator2>::value &&
0111                   __has_random_access_iterator_category_or_concept<_ForwardOutIterator>::value) {
0112       auto __res = __cpu_traits<_Backend>::__for_each(
0113           __first1,
0114           __last1,
0115           [&__policy, __op, __first1, __first2, __result](
0116               _ForwardIterator1 __brick_first, _ForwardIterator1 __brick_last) {
0117             using _TransformBinaryUnseq =
0118                 __pstl::__transform_binary<_Backend, __remove_parallel_policy_t<_RawExecutionPolicy>>;
0119             return _TransformBinaryUnseq()(
0120                 std::__remove_parallel_policy(__policy),
0121                 __brick_first,
0122                 __brick_last,
0123                 __first2 + (__brick_first - __first1),
0124                 __result + (__brick_first - __first1),
0125                 __op);
0126           });
0127       if (!__res)
0128         return nullopt;
0129       return __result + (__last1 - __first1);
0130     } else if constexpr (__is_unsequenced_execution_policy_v<_RawExecutionPolicy> &&
0131                          __has_random_access_iterator_category_or_concept<_ForwardIterator1>::value &&
0132                          __has_random_access_iterator_category_or_concept<_ForwardIterator2>::value &&
0133                          __has_random_access_iterator_category_or_concept<_ForwardOutIterator>::value) {
0134       return __pstl::__simd_transform(
0135           __first1,
0136           __last1 - __first1,
0137           __first2,
0138           __result,
0139           [&](__iter_reference<_ForwardIterator1> __in1,
0140               __iter_reference<_ForwardIterator2> __in2,
0141               __iter_reference<_ForwardOutIterator> __out_value) { __out_value = __op(__in1, __in2); });
0142     } else {
0143       return std::transform(__first1, __last1, __first2, __result, __op);
0144     }
0145   }
0146 };
0147
0148 } // namespace __pstl
0149 _LIBCPP_END_NAMESPACE_STD
0150
0151 _LIBCPP_POP_MACROS
0152
0153 #endif // _LIBCPP___CXX03___PSTL_CPU_ALGOS_TRANSFORM_H