libcxx/include/__pstl/cpu_algos/cpu_traits.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___PSTL_CPU_ALGOS_CPU_TRAITS_H
  10 #define _LIBCPP___PSTL_CPU_ALGOS_CPU_TRAITS_H
  11
  12 #include <__config>
  13
  14 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  15 #  pragma GCC system_header
  16 #endif
  17
  18 _LIBCPP_PUSH_MACROS
  19 #include <__undef_macros>
  20
  21 #if _LIBCPP_STD_VER >= 17
  22
  23 _LIBCPP_BEGIN_NAMESPACE_STD
  24 namespace __pstl {
  25
  26 // __cpu_traits
  27 //
  28 // This traits class encapsulates the basis operations for a CPU-based implementation of the PSTL.
  29 // All the operations in the PSTL can be implemented from these basis operations, so a pure CPU backend
  30 // only needs to customize these traits in order to get an implementation of the whole PSTL.
  31 //
  32 // Basis operations
  33 // ================
  34 //
  35 //  template <class _RandomAccessIterator, class _Functor>
  36 //  optional<__empty> __for_each(_RandomAccessIterator __first, _RandomAccessIterator __last, _Functor __func);
  37 //    - __func must take a subrange of [__first, __last) that should be executed in serial
  38 //
  39 //  template <class _Iterator, class _UnaryOp, class _Tp, class _BinaryOp, class _Reduction>
  40 //  optional<_Tp> __transform_reduce(_Iterator __first, _Iterator __last, _UnaryOp, _Tp __init, _BinaryOp, _Reduction);
  41 //
  42 //  template <class _RandomAccessIterator1,
  43 //            class _RandomAccessIterator2,
  44 //            class _RandomAccessIterator3,
  45 //            class _Compare,
  46 //            class _LeafMerge>
  47 //  optional<_RandomAccessIterator3> __merge(_RandomAccessIterator1 __first1,
  48 //                                           _RandomAccessIterator1 __last1,
  49 //                                           _RandomAccessIterator2 __first2,
  50 //                                           _RandomAccessIterator2 __last2,
  51 //                                           _RandomAccessIterator3 __outit,
  52 //                                           _Compare __comp,
  53 //                                           _LeafMerge __leaf_merge);
  54 //
  55 //  template <class _RandomAccessIterator, class _Comp, class _LeafSort>
  56 //  optional<__empty> __stable_sort(_RandomAccessIterator __first,
  57 //                                  _RandomAccessIterator __last,
  58 //                                  _Comp __comp,
  59 //                                  _LeafSort __leaf_sort);
  60 //
  61 //   void __cancel_execution();
  62 //      Cancel the execution of other jobs - they aren't needed anymore. This is not a binding request,
  63 //      some backends may not actually be able to cancel jobs.
  64 //
  65 //   constexpr size_t __lane_size;
  66 //      Size of SIMD lanes.
  67 //      TODO: Merge this with __native_vector_size from __algorithm/simd_utils.h
  68 //
  69 //
  70 // Exception handling
  71 // ==================
  72 //
  73 // CPU backends are expected to report errors (i.e. failure to allocate) by returning a disengaged `optional` from their
  74 // implementation. Exceptions shouldn't be used to report an internal failure-to-allocate, since all exceptions are
  75 // turned into a program termination at the front-end level. When a backend returns a disengaged `optional` to the
  76 // frontend, the frontend will turn that into a call to `std::__throw_bad_alloc();` to report the internal failure to
  77 // the user.
  78
  79 template <class _Backend>
  80 struct __cpu_traits;
  81
  82 } // namespace __pstl
  83 _LIBCPP_END_NAMESPACE_STD
  84
  85 #endif // _LIBCPP_STD_VER >= 17
  86
  87 _LIBCPP_POP_MACROS
  88
  89 #endif // _LIBCPP___PSTL_CPU_ALGOS_CPU_TRAITS_H