libcxx/include/__cxx03/__pstl/cpu_algos/any_of.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___CXX03___PSTL_CPU_ALGOS_ANY_OF_H
  10 #define _LIBCPP___CXX03___PSTL_CPU_ALGOS_ANY_OF_H
  11
  12 #include <__cxx03/__algorithm/any_of.h>
  13 #include <__cxx03/__assert>
  14 #include <__cxx03/__atomic/atomic.h>
  15 #include <__cxx03/__atomic/memory_order.h>
  16 #include <__cxx03/__config>
  17 #include <__cxx03/__iterator/concepts.h>
  18 #include <__cxx03/__pstl/backend_fwd.h>
  19 #include <__cxx03/__pstl/cpu_algos/cpu_traits.h>
  20 #include <__cxx03/__type_traits/is_execution_policy.h>
  21 #include <__cxx03/__utility/move.h>
  22 #include <__cxx03/__utility/pair.h>
  23 #include <__cxx03/cstdint>
  24 #include <__cxx03/optional>
  25
  26 _LIBCPP_PUSH_MACROS
  27 #include <__cxx03/__undef_macros>
  28
  29 _LIBCPP_BEGIN_NAMESPACE_STD
  30 namespace __pstl {
  31
  32 template <class _Backend, class _Index, class _Brick>
  33 _LIBCPP_HIDE_FROM_ABI optional<bool> __parallel_or(_Index __first, _Index __last, _Brick __f) {
  34   std::atomic<bool> __found(false);
  35   auto __ret = __cpu_traits<_Backend>::__for_each(__first, __last, [__f, &__found](_Index __i, _Index __j) {
  36     if (!__found.load(std::memory_order_relaxed) && __f(__i, __j)) {
  37       __found.store(true, std::memory_order_relaxed);
  38       __cpu_traits<_Backend>::__cancel_execution();
  39     }
  40   });
  41   if (!__ret)
  42     return nullopt;
  43   return static_cast<bool>(__found);
  44 }
  45
  46 // TODO: check whether __simd_first() can be used here
  47 template <class _Index, class _DifferenceType, class _Pred>
  48 _LIBCPP_HIDE_FROM_ABI bool __simd_or(_Index __first, _DifferenceType __n, _Pred __pred) noexcept {
  49   _DifferenceType __block_size = 4 < __n ? 4 : __n;
  50   const _Index __last          = __first + __n;
  51   while (__last != __first) {
  52     int32_t __flag = 1;
  53     _PSTL_PRAGMA_SIMD_REDUCTION(& : __flag)
  54     for (_DifferenceType __i = 0; __i < __block_size; ++__i)
  55       if (__pred(*(__first + __i)))
  56         __flag = 0;
  57     if (!__flag)
  58       return true;
  59
  60     __first += __block_size;
  61     if (__last - __first >= __block_size << 1) {
  62       // Double the block _Size.  Any unnecessary iterations can be amortized against work done so far.
  63       __block_size <<= 1;
  64     } else {
  65       __block_size = __last - __first;
  66     }
  67   }
  68   return false;
  69 }
  70
  71 template <class _Backend, class _RawExecutionPolicy>
  72 struct __cpu_parallel_any_of {
  73   template <class _Policy, class _ForwardIterator, class _Predicate>
  74   _LIBCPP_HIDE_FROM_ABI optional<bool>
  75   operator()(_Policy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Predicate __pred) const noexcept {
  76     if constexpr (__is_parallel_execution_policy_v<_RawExecutionPolicy> &&
  77                   __has_random_access_iterator_category_or_concept<_ForwardIterator>::value) {
  78       return __pstl::__parallel_or<_Backend>(
  79           __first, __last, [&__policy, &__pred](_ForwardIterator __brick_first, _ForwardIterator __brick_last) {
  80             using _AnyOfUnseq = __pstl::__any_of<_Backend, __remove_parallel_policy_t<_RawExecutionPolicy>>;
  81             auto __res = _AnyOfUnseq()(std::__remove_parallel_policy(__policy), __brick_first, __brick_last, __pred);
  82             _LIBCPP_ASSERT_INTERNAL(__res, "unseq/seq should never try to allocate!");
  83             return *std::move(__res);
  84           });
  85     } else if constexpr (__is_unsequenced_execution_policy_v<_RawExecutionPolicy> &&
  86                          __has_random_access_iterator_category_or_concept<_ForwardIterator>::value) {
  87       return __pstl::__simd_or(__first, __last - __first, __pred);
  88     } else {
  89       return std::any_of(__first, __last, __pred);
  90     }
  91   }
  92 };
  93
  94 } // namespace __pstl
  95 _LIBCPP_END_NAMESPACE_STD
  96
  97 _LIBCPP_POP_MACROS
  98
  99 #endif // _LIBCPP___CXX03___PSTL_CPU_ALGOS_ANY_OF_H