__pstl/cpu_algos/any_of.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_ANY_OF_H
0010 #define _LIBCPP___CXX03___PSTL_CPU_ALGOS_ANY_OF_H
0011
0012 #include <__cxx03/__algorithm/any_of.h>
0013 #include <__cxx03/__assert>
0014 #include <__cxx03/__atomic/atomic.h>
0015 #include <__cxx03/__atomic/memory_order.h>
0016 #include <__cxx03/__config>
0017 #include <__cxx03/__iterator/concepts.h>
0018 #include <__cxx03/__pstl/backend_fwd.h>
0019 #include <__cxx03/__pstl/cpu_algos/cpu_traits.h>
0020 #include <__cxx03/__type_traits/is_execution_policy.h>
0021 #include <__cxx03/__utility/move.h>
0022 #include <__cxx03/__utility/pair.h>
0023 #include <__cxx03/cstdint>
0024 #include <__cxx03/optional>
0025
0026 _LIBCPP_PUSH_MACROS
0027 #include <__cxx03/__undef_macros>
0028
0029 _LIBCPP_BEGIN_NAMESPACE_STD
0030 namespace __pstl {
0031
0032 template <class _Backend, class _Index, class _Brick>
0033 _LIBCPP_HIDE_FROM_ABI optional<bool> __parallel_or(_Index __first, _Index __last, _Brick __f) {
0034   std::atomic<bool> __found(false);
0035   auto __ret = __cpu_traits<_Backend>::__for_each(__first, __last, [__f, &__found](_Index __i, _Index __j) {
0036     if (!__found.load(std::memory_order_relaxed) && __f(__i, __j)) {
0037       __found.store(true, std::memory_order_relaxed);
0038       __cpu_traits<_Backend>::__cancel_execution();
0039     }
0040   });
0041   if (!__ret)
0042     return nullopt;
0043   return static_cast<bool>(__found);
0044 }
0045
0046 // TODO: check whether __simd_first() can be used here
0047 template <class _Index, class _DifferenceType, class _Pred>
0048 _LIBCPP_HIDE_FROM_ABI bool __simd_or(_Index __first, _DifferenceType __n, _Pred __pred) noexcept {
0049   _DifferenceType __block_size = 4 < __n ? 4 : __n;
0050   const _Index __last          = __first + __n;
0051   while (__last != __first) {
0052     int32_t __flag = 1;
0053     _PSTL_PRAGMA_SIMD_REDUCTION(& : __flag)
0054     for (_DifferenceType __i = 0; __i < __block_size; ++__i)
0055       if (__pred(*(__first + __i)))
0056         __flag = 0;
0057     if (!__flag)
0058       return true;
0059
0060     __first += __block_size;
0061     if (__last - __first >= __block_size << 1) {
0062       // Double the block _Size.  Any unnecessary iterations can be amortized against work done so far.
0063       __block_size <<= 1;
0064     } else {
0065       __block_size = __last - __first;
0066     }
0067   }
0068   return false;
0069 }
0070
0071 template <class _Backend, class _RawExecutionPolicy>
0072 struct __cpu_parallel_any_of {
0073   template <class _Policy, class _ForwardIterator, class _Predicate>
0074   _LIBCPP_HIDE_FROM_ABI optional<bool>
0075   operator()(_Policy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Predicate __pred) const noexcept {
0076     if constexpr (__is_parallel_execution_policy_v<_RawExecutionPolicy> &&
0077                   __has_random_access_iterator_category_or_concept<_ForwardIterator>::value) {
0078       return __pstl::__parallel_or<_Backend>(
0079           __first, __last, [&__policy, &__pred](_ForwardIterator __brick_first, _ForwardIterator __brick_last) {
0080             using _AnyOfUnseq = __pstl::__any_of<_Backend, __remove_parallel_policy_t<_RawExecutionPolicy>>;
0081             auto __res = _AnyOfUnseq()(std::__remove_parallel_policy(__policy), __brick_first, __brick_last, __pred);
0082             _LIBCPP_ASSERT_INTERNAL(__res, "unseq/seq should never try to allocate!");
0083             return *std::move(__res);
0084           });
0085     } else if constexpr (__is_unsequenced_execution_policy_v<_RawExecutionPolicy> &&
0086                          __has_random_access_iterator_category_or_concept<_ForwardIterator>::value) {
0087       return __pstl::__simd_or(__first, __last - __first, __pred);
0088     } else {
0089       return std::any_of(__first, __last, __pred);
0090     }
0091   }
0092 };
0093
0094 } // namespace __pstl
0095 _LIBCPP_END_NAMESPACE_STD
0096
0097 _LIBCPP_POP_MACROS
0098
0099 #endif // _LIBCPP___CXX03___PSTL_CPU_ALGOS_ANY_OF_H