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 template <size_t _Np, class _Tp>
26 _LIBCPP_NODISCARD _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp* __assume_aligned(_Tp* __ptr) {
27   static_assert(_Np != 0 && (_Np & (_Np - 1)) == 0, "std::assume_aligned<N>(p) requires N to be a power of two");
28 
29   if (__libcpp_is_constant_evaluated()) {
30     (void)__builtin_assume_aligned(__ptr, _Np);
31     return __ptr;
32   } else {
33     _LIBCPP_ASSERT_ARGUMENT_WITHIN_DOMAIN(
34         reinterpret_cast<uintptr_t>(__ptr) % _Np == 0, "Alignment assumption is violated");
35     return static_cast<_Tp*>(__builtin_assume_aligned(__ptr, _Np));
36   }
37 }
38 
39 #if _LIBCPP_STD_VER >= 20
40 
41 template <size_t _Np, class _Tp>
42 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp* assume_aligned(_Tp* __ptr) {
43   return std::__assume_aligned<_Np>(__ptr);
44 }
45 
46 #endif // _LIBCPP_STD_VER >= 20
47 
48 _LIBCPP_END_NAMESPACE_STD
49 
50 #endif // _LIBCPP___MEMORY_ASSUME_ALIGNED_H
51