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//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP___MEMORY_ASSUME_ALIGNED_H
11#define _LIBCPP___MEMORY_ASSUME_ALIGNED_H
12
13#include <__assert>
14#include <__config>
15#include <__type_traits/is_constant_evaluated.h>
16#include <cstddef>
17#include <cstdint>
18
19#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
20#  pragma GCC system_header
21#endif
22
23_LIBCPP_BEGIN_NAMESPACE_STD
24
25#if _LIBCPP_STD_VER > 17
26
27template <size_t _Np, class _Tp>
28[[nodiscard]]
29_LIBCPP_HIDE_FROM_ABI
30constexpr _Tp* assume_aligned(_Tp* __ptr) {
31  static_assert(_Np != 0 && (_Np & (_Np - 1)) == 0,
32    "std::assume_aligned<N>(p) requires N to be a power of two");
33
34  if (is_constant_evaluated()) {
35    return __ptr;
36  } else {
37    _LIBCPP_ASSERT(reinterpret_cast<uintptr_t>(__ptr) % _Np == 0, "Alignment assumption is violated");
38    return static_cast<_Tp*>(__builtin_assume_aligned(__ptr, _Np));
39  }
40}
41
42#endif // _LIBCPP_STD_VER > 17
43
44_LIBCPP_END_NAMESPACE_STD
45
46#endif // _LIBCPP___MEMORY_ASSUME_ALIGNED_H
47