libcxx/src/pstl/libdispatch.cpp

   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 #include <__algorithm/min.h>
  10 #include <__algorithm/pstl_backends/cpu_backends/libdispatch.h>
  11 #include <__config>
  12 #include <dispatch/dispatch.h>
  13
  14 _LIBCPP_BEGIN_NAMESPACE_STD
  15
  16 namespace __par_backend::inline __libdispatch {
  17
  18 void __dispatch_apply(size_t chunk_count, void* context, void (*func)(void* context, size_t chunk)) noexcept {
  19   ::dispatch_apply_f(chunk_count, DISPATCH_APPLY_AUTO, context, func);
  20 }
  21
  22 __chunk_partitions __partition_chunks(ptrdiff_t element_count) noexcept {
  23   __chunk_partitions partitions;
  24   partitions.__chunk_count_      = std::max<ptrdiff_t>(1, element_count / 256);
  25   partitions.__chunk_size_       = element_count / partitions.__chunk_count_;
  26   partitions.__first_chunk_size_ = element_count - (partitions.__chunk_count_ - 1) * partitions.__chunk_size_;
  27   if (partitions.__chunk_count_ == 0 && element_count > 0)
  28     partitions.__chunk_count_ = 1;
  29   return partitions;
  30 }
  31
  32 // NOLINTNEXTLINE(llvm-namespace-comment) // This is https://llvm.org/PR56804
  33 } // namespace __par_backend::inline __libdispatch
  34
  35 _LIBCPP_END_NAMESPACE_STD