xref: /freebsd-src/contrib/llvm-project/libcxx/include/__memory/assume_aligned.h (revision 7a6dacaca14b62ca4b74406814becb87a3fefac0)
181ad6265SDimitry Andric // -*- C++ -*-
281ad6265SDimitry Andric //===----------------------------------------------------------------------===//
381ad6265SDimitry Andric //
481ad6265SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
581ad6265SDimitry Andric // See https://llvm.org/LICENSE.txt for license information.
681ad6265SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
781ad6265SDimitry Andric //
881ad6265SDimitry Andric //===----------------------------------------------------------------------===//
981ad6265SDimitry Andric 
1081ad6265SDimitry Andric #ifndef _LIBCPP___MEMORY_ASSUME_ALIGNED_H
1181ad6265SDimitry Andric #define _LIBCPP___MEMORY_ASSUME_ALIGNED_H
1281ad6265SDimitry Andric 
1381ad6265SDimitry Andric #include <__assert>
1481ad6265SDimitry Andric #include <__config>
15bdd1243dSDimitry Andric #include <__type_traits/is_constant_evaluated.h>
1681ad6265SDimitry Andric #include <cstddef>
1781ad6265SDimitry Andric #include <cstdint>
1881ad6265SDimitry Andric 
1981ad6265SDimitry Andric #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
2081ad6265SDimitry Andric #  pragma GCC system_header
2181ad6265SDimitry Andric #endif
2281ad6265SDimitry Andric 
2381ad6265SDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD
2481ad6265SDimitry Andric 
2581ad6265SDimitry Andric template <size_t _Np, class _Tp>
__assume_aligned(_Tp * __ptr)265f757f3fSDimitry Andric _LIBCPP_NODISCARD _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp* __assume_aligned(_Tp* __ptr) {
27cb14a3feSDimitry Andric   static_assert(_Np != 0 && (_Np & (_Np - 1)) == 0, "std::assume_aligned<N>(p) requires N to be a power of two");
2881ad6265SDimitry Andric 
295f757f3fSDimitry Andric   if (__libcpp_is_constant_evaluated()) {
30*7a6dacacSDimitry Andric     (void)__builtin_assume_aligned(__ptr, _Np);
3181ad6265SDimitry Andric     return __ptr;
3281ad6265SDimitry Andric   } else {
33*7a6dacacSDimitry Andric     _LIBCPP_ASSERT_ARGUMENT_WITHIN_DOMAIN(
34*7a6dacacSDimitry Andric         reinterpret_cast<uintptr_t>(__ptr) % _Np == 0, "Alignment assumption is violated");
3581ad6265SDimitry Andric     return static_cast<_Tp*>(__builtin_assume_aligned(__ptr, _Np));
3681ad6265SDimitry Andric   }
3781ad6265SDimitry Andric }
3881ad6265SDimitry Andric 
395f757f3fSDimitry Andric #if _LIBCPP_STD_VER >= 20
405f757f3fSDimitry Andric 
415f757f3fSDimitry Andric template <size_t _Np, class _Tp>
assume_aligned(_Tp * __ptr)425f757f3fSDimitry Andric [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp* assume_aligned(_Tp* __ptr) {
435f757f3fSDimitry Andric   return std::__assume_aligned<_Np>(__ptr);
445f757f3fSDimitry Andric }
455f757f3fSDimitry Andric 
4606c3fb27SDimitry Andric #endif // _LIBCPP_STD_VER >= 20
4781ad6265SDimitry Andric 
4881ad6265SDimitry Andric _LIBCPP_END_NAMESPACE_STD
4981ad6265SDimitry Andric 
5081ad6265SDimitry Andric #endif // _LIBCPP___MEMORY_ASSUME_ALIGNED_H
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