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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_TRANSFORM_REDUCE_H
10#define _LIBCPP___PSTL_CPU_ALGOS_TRANSFORM_REDUCE_H
11
12#include <__assert>
13#include <__config>
14#include <__iterator/concepts.h>
15#include <__iterator/iterator_traits.h>
16#include <__numeric/transform_reduce.h>
17#include <__pstl/backend_fwd.h>
18#include <__pstl/cpu_algos/cpu_traits.h>
19#include <__type_traits/desugars_to.h>
20#include <__type_traits/is_arithmetic.h>
21#include <__type_traits/is_execution_policy.h>
22#include <__utility/move.h>
23#include <optional>
24
25#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
26# pragma GCC system_header
27#endif
28
29_LIBCPP_PUSH_MACROS
30#include <__undef_macros>
31
32#if _LIBCPP_STD_VER >= 17
33
34_LIBCPP_BEGIN_NAMESPACE_STD
35namespace __pstl {
36
37template <typename _Backend,
38 typename _DifferenceType,
39 typename _Tp,
40 typename _BinaryOperation,
41 typename _UnaryOperation,
42 typename _UnaryResult = invoke_result_t<_UnaryOperation, _DifferenceType>,
43 __enable_if_t<__desugars_to_v<__plus_tag, _BinaryOperation, _Tp, _UnaryResult> && is_arithmetic_v<_Tp> &&
44 is_arithmetic_v<_UnaryResult>,
45 int> = 0>
46_LIBCPP_HIDE_FROM_ABI _Tp
47__simd_transform_reduce(_DifferenceType __n, _Tp __init, _BinaryOperation, _UnaryOperation __f) noexcept {
48 _PSTL_PRAGMA_SIMD_REDUCTION(+ : __init)
49 for (_DifferenceType __i = 0; __i < __n; ++__i)
50 __init += __f(__i);
51 return __init;
52}
53
54template <typename _Backend,
55 typename _Size,
56 typename _Tp,
57 typename _BinaryOperation,
58 typename _UnaryOperation,
59 typename _UnaryResult = invoke_result_t<_UnaryOperation, _Size>,
60 __enable_if_t<!(__desugars_to_v<__plus_tag, _BinaryOperation, _Tp, _UnaryResult> && is_arithmetic_v<_Tp> &&
61 is_arithmetic_v<_UnaryResult>),
62 int> = 0>
63_LIBCPP_HIDE_FROM_ABI _Tp
64__simd_transform_reduce(_Size __n, _Tp __init, _BinaryOperation __binary_op, _UnaryOperation __f) noexcept {
65 constexpr size_t __lane_size = __cpu_traits<_Backend>::__lane_size;
66 const _Size __block_size = __lane_size / sizeof(_Tp);
67 if (__n > 2 * __block_size && __block_size > 1) {
68 alignas(__lane_size) char __lane_buffer[__lane_size];
69 _Tp* __lane = reinterpret_cast<_Tp*>(__lane_buffer);
70
71 // initializer
72 _PSTL_PRAGMA_SIMD
73 for (_Size __i = 0; __i < __block_size; ++__i) {
74 ::new (__lane + __i) _Tp(__binary_op(__f(__i), __f(__block_size + __i)));
75 }
76 // main loop
77 _Size __i = 2 * __block_size;
78 const _Size __last_iteration = __block_size * (__n / __block_size);
79 for (; __i < __last_iteration; __i += __block_size) {
80 _PSTL_PRAGMA_SIMD
81 for (_Size __j = 0; __j < __block_size; ++__j) {
82 __lane[__j] = __binary_op(std::move(__lane[__j]), __f(__i + __j));
83 }
84 }
85 // remainder
86 _PSTL_PRAGMA_SIMD
87 for (_Size __j = 0; __j < __n - __last_iteration; ++__j) {
88 __lane[__j] = __binary_op(std::move(__lane[__j]), __f(__last_iteration + __j));
89 }
90 // combiner
91 for (_Size __j = 0; __j < __block_size; ++__j) {
92 __init = __binary_op(std::move(__init), std::move(__lane[__j]));
93 }
94 // destroyer
95 _PSTL_PRAGMA_SIMD
96 for (_Size __j = 0; __j < __block_size; ++__j) {
97 __lane[__j].~_Tp();
98 }
99 } else {
100 for (_Size __i = 0; __i < __n; ++__i) {
101 __init = __binary_op(std::move(__init), __f(__i));
102 }
103 }
104 return __init;
105}
106
107template <class _Backend, class _RawExecutionPolicy>
108struct __cpu_parallel_transform_reduce_binary {
109 template <class _Policy,
110 class _ForwardIterator1,
111 class _ForwardIterator2,
112 class _Tp,
113 class _BinaryOperation1,
114 class _BinaryOperation2>
115 _LIBCPP_HIDE_FROM_ABI optional<_Tp> operator()(
116 _Policy&& __policy,
117 _ForwardIterator1 __first1,
118 _ForwardIterator1 __last1,
119 _ForwardIterator2 __first2,
120 _Tp __init,
121 _BinaryOperation1 __reduce,
122 _BinaryOperation2 __transform) const noexcept {
123 if constexpr (__is_parallel_execution_policy_v<_RawExecutionPolicy> &&
124 __has_random_access_iterator_category_or_concept<_ForwardIterator1>::value &&
125 __has_random_access_iterator_category_or_concept<_ForwardIterator2>::value) {
126 return __cpu_traits<_Backend>::__transform_reduce(
127 __first1,
128 std::move(__last1),
129 [__first1, __first2, __transform](_ForwardIterator1 __iter) {
130 return __transform(*__iter, *(__first2 + (__iter - __first1)));
131 },
132 std::move(__init),
133 std::move(__reduce),
134 [&__policy, __first1, __first2, __reduce, __transform](
135 _ForwardIterator1 __brick_first, _ForwardIterator1 __brick_last, _Tp __brick_init) {
136 using _TransformReduceBinaryUnseq =
137 __pstl::__transform_reduce_binary<_Backend, __remove_parallel_policy_t<_RawExecutionPolicy>>;
138 return *_TransformReduceBinaryUnseq()(
139 std::__remove_parallel_policy(__policy),
140 __brick_first,
141 std::move(__brick_last),
142 __first2 + (__brick_first - __first1),
143 std::move(__brick_init),
144 std::move(__reduce),
145 std::move(__transform));
146 });
147 } else if constexpr (__is_unsequenced_execution_policy_v<_RawExecutionPolicy> &&
148 __has_random_access_iterator_category_or_concept<_ForwardIterator1>::value &&
149 __has_random_access_iterator_category_or_concept<_ForwardIterator2>::value) {
150 return __pstl::__simd_transform_reduce<_Backend>(
151 __last1 - __first1, std::move(__init), std::move(__reduce), [&](__iter_diff_t<_ForwardIterator1> __i) {
152 return __transform(__first1[__i], __first2[__i]);
153 });
154 } else {
155 return std::transform_reduce(
156 std::move(__first1),
157 std::move(__last1),
158 std::move(__first2),
159 std::move(__init),
160 std::move(__reduce),
161 std::move(__transform));
162 }
163 }
164};
165
166template <class _Backend, class _RawExecutionPolicy>
167struct __cpu_parallel_transform_reduce {
168 template <class _Policy, class _ForwardIterator, class _Tp, class _BinaryOperation, class _UnaryOperation>
169 _LIBCPP_HIDE_FROM_ABI optional<_Tp>
170 operator()(_Policy&& __policy,
171 _ForwardIterator __first,
172 _ForwardIterator __last,
173 _Tp __init,
174 _BinaryOperation __reduce,
175 _UnaryOperation __transform) const noexcept {
176 if constexpr (__is_parallel_execution_policy_v<_RawExecutionPolicy> &&
177 __has_random_access_iterator_category_or_concept<_ForwardIterator>::value) {
178 return __cpu_traits<_Backend>::__transform_reduce(
179 std::move(__first),
180 std::move(__last),
181 [__transform](_ForwardIterator __iter) { return __transform(*__iter); },
182 std::move(__init),
183 __reduce,
184 [&__policy, __transform, __reduce](auto __brick_first, auto __brick_last, _Tp __brick_init) {
185 using _TransformReduceUnseq =
186 __pstl::__transform_reduce<_Backend, __remove_parallel_policy_t<_RawExecutionPolicy>>;
187 auto __res = _TransformReduceUnseq()(
188 std::__remove_parallel_policy(__policy),
189 std::move(__brick_first),
190 std::move(__brick_last),
191 std::move(__brick_init),
192 std::move(__reduce),
193 std::move(__transform));
194 _LIBCPP_ASSERT_INTERNAL(__res, "unseq/seq should never try to allocate!");
195 return *std::move(__res);
196 });
197 } else if constexpr (__is_unsequenced_execution_policy_v<_RawExecutionPolicy> &&
198 __has_random_access_iterator_category_or_concept<_ForwardIterator>::value) {
199 return __pstl::__simd_transform_reduce<_Backend>(
200 __last - __first,
201 std::move(__init),
202 std::move(__reduce),
203 [=, &__transform](__iter_diff_t<_ForwardIterator> __i) { return __transform(__first[__i]); });
204 } else {
205 return std::transform_reduce(
206 std::move(__first), std::move(__last), std::move(__init), std::move(__reduce), std::move(__transform));
207 }
208 }
209};
210
211} // namespace __pstl
212_LIBCPP_END_NAMESPACE_STD
213
214#endif // _LIBCPP_STD_VER >= 17
215
216_LIBCPP_POP_MACROS
217
218#endif // _LIBCPP___PSTL_CPU_ALGOS_TRANSFORM_REDUCE_H
219

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source code of libcxx/include/__pstl/cpu_algos/transform_reduce.h