1//===----------------------------------------------------------------------===// 2// 3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4// See https://llvm.org/LICENSE.txt for license information. 5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6// 7//===----------------------------------------------------------------------===// 8 9#ifndef _LIBCPP___MEMORY_ALIGNED_ALLOC_H 10#define _LIBCPP___MEMORY_ALIGNED_ALLOC_H 11 12#include <__config> 13#include <cstddef> 14#include <cstdlib> 15 16#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 17# pragma GCC system_header 18#endif 19 20_LIBCPP_BEGIN_NAMESPACE_STD 21 22#ifndef _LIBCPP_HAS_NO_LIBRARY_ALIGNED_ALLOCATION 23 24// Low-level helpers to call the aligned allocation and deallocation functions 25// on the target platform. This is used to implement libc++'s own memory 26// allocation routines -- if you need to allocate memory inside the library, 27// chances are that you want to use `__libcpp_allocate` instead. 28// 29// Returns the allocated memory, or `nullptr` on failure. 30inline _LIBCPP_HIDE_FROM_ABI void* __libcpp_aligned_alloc(std::size_t __alignment, std::size_t __size) { 31# if defined(_LIBCPP_MSVCRT_LIKE) 32 return ::_aligned_malloc(__size, __alignment); 33# elif _LIBCPP_STD_VER >= 17 && !defined(_LIBCPP_HAS_NO_C11_ALIGNED_ALLOC) 34 // aligned_alloc() requires that __size is a multiple of __alignment, 35 // but for C++ [new.delete.general], only states "if the value of an 36 // alignment argument passed to any of these functions is not a valid 37 // alignment value, the behavior is undefined". 38 // To handle calls such as ::operator new(1, std::align_val_t(128)), we 39 // round __size up to the next multiple of __alignment. 40 size_t __rounded_size = (__size + __alignment - 1) & ~(__alignment - 1); 41 // Rounding up could have wrapped around to zero, so we have to add another 42 // max() ternary to the actual call site to avoid succeeded in that case. 43 return ::aligned_alloc(__alignment, __size > __rounded_size ? __size : __rounded_size); 44# else 45 void* __result = nullptr; 46 (void)::posix_memalign(&__result, __alignment, __size); 47 // If posix_memalign fails, __result is unmodified so we still return `nullptr`. 48 return __result; 49# endif 50} 51 52inline _LIBCPP_HIDE_FROM_ABI void __libcpp_aligned_free(void* __ptr) { 53# if defined(_LIBCPP_MSVCRT_LIKE) 54 ::_aligned_free(__ptr); 55# else 56 ::free(__ptr); 57# endif 58} 59 60#endif // !_LIBCPP_HAS_NO_LIBRARY_ALIGNED_ALLOCATION 61 62_LIBCPP_END_NAMESPACE_STD 63 64#endif // _LIBCPP___MEMORY_ALIGNED_ALLOC_H 65