master
1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8// Kokkos v. 4.0
9// Copyright (2022) National Technology & Engineering
10// Solutions of Sandia, LLC (NTESS).
11//
12// Under the terms of Contract DE-NA0003525 with NTESS,
13// the U.S. Government retains certain rights in this software.
14//
15//===---------------------------------------------------------------------===//
16
17#ifndef _LIBCPP___MDSPAN_ALIGNED_ACCESSOR_H
18#define _LIBCPP___MDSPAN_ALIGNED_ACCESSOR_H
19
20#include <__config>
21#include <__cstddef/size_t.h>
22#include <__mdspan/default_accessor.h>
23#include <__memory/assume_aligned.h>
24#include <__type_traits/is_abstract.h>
25#include <__type_traits/is_array.h>
26#include <__type_traits/is_convertible.h>
27#include <__type_traits/remove_const.h>
28
29#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
30# pragma GCC system_header
31#endif
32
33_LIBCPP_PUSH_MACROS
34#include <__undef_macros>
35
36_LIBCPP_BEGIN_NAMESPACE_STD
37
38#if _LIBCPP_STD_VER >= 26
39
40template <class _ElementType, size_t _ByteAlignment>
41struct aligned_accessor {
42 static_assert(_ByteAlignment != 0 && (_ByteAlignment & (_ByteAlignment - 1)) == 0,
43 "aligned_accessor: byte alignment must be a power of two");
44 static_assert(_ByteAlignment >= alignof(_ElementType), "aligned_accessor: insufficient byte alignment");
45 static_assert(!is_array_v<_ElementType>, "aligned_accessor: template argument may not be an array type");
46 static_assert(!is_abstract_v<_ElementType>, "aligned_accessor: template argument may not be an abstract class");
47
48 using offset_policy = default_accessor<_ElementType>;
49 using element_type = _ElementType;
50 using reference = _ElementType&;
51 using data_handle_type = _ElementType*;
52
53 static constexpr size_t byte_alignment = _ByteAlignment;
54
55 _LIBCPP_HIDE_FROM_ABI constexpr aligned_accessor() noexcept = default;
56
57 template <class _OtherElementType, size_t _OtherByteAlignment>
58 requires(is_convertible_v<_OtherElementType (*)[], element_type (*)[]> && _OtherByteAlignment >= byte_alignment)
59 _LIBCPP_HIDE_FROM_ABI constexpr aligned_accessor(aligned_accessor<_OtherElementType, _OtherByteAlignment>) noexcept {}
60
61 template <class _OtherElementType>
62 requires(is_convertible_v<_OtherElementType (*)[], element_type (*)[]>)
63 _LIBCPP_HIDE_FROM_ABI explicit constexpr aligned_accessor(default_accessor<_OtherElementType>) noexcept {}
64
65 template <class _OtherElementType>
66 requires(is_convertible_v<element_type (*)[], _OtherElementType (*)[]>)
67 _LIBCPP_HIDE_FROM_ABI constexpr operator default_accessor<_OtherElementType>() const noexcept {
68 return {};
69 }
70
71 _LIBCPP_HIDE_FROM_ABI constexpr reference access(data_handle_type __p, size_t __i) const noexcept {
72 return std::assume_aligned<byte_alignment>(__p)[__i];
73 }
74
75 _LIBCPP_HIDE_FROM_ABI constexpr typename offset_policy::data_handle_type
76 offset(data_handle_type __p, size_t __i) const noexcept {
77 return std::assume_aligned<byte_alignment>(__p) + __i;
78 }
79};
80
81#endif // _LIBCPP_STD_VER >= 26
82
83_LIBCPP_END_NAMESPACE_STD
84
85_LIBCPP_POP_MACROS
86
87#endif // _LIBCPP___MDSPAN_ALIGNED_ACCESSOR_H