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 <cstddef> |
16 | #include <cstdint> |
17 | #include <type_traits> // for is_constant_evaluated() |
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 | |
27 | template <size_t _Np, class _Tp> |
28 | [[nodiscard]] |
29 | _LIBCPP_HIDE_FROM_ABI |
30 | constexpr _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 | |