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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-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef _LIBCPP_SRC_ALIGNED_ALLOC_H10#define _LIBCPP_SRC_ALIGNED_ALLOC_H11 12#include <__config>13#include <cstdlib>14 15#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)16# pragma GCC system_header17#endif18 19_LIBCPP_BEGIN_NAMESPACE_STD20 21#if _LIBCPP_HAS_LIBRARY_ALIGNED_ALLOCATION22 23// Low-level helpers to call the aligned allocation and deallocation functions24// on the target platform. This is used to implement libc++'s own memory25// allocation routines -- if you need to allocate memory inside the library,26// chances are that you want to use `__libcpp_allocate` instead.27//28// Returns the allocated memory, or `nullptr` on failure.29inline _LIBCPP_HIDE_FROM_ABI void* __libcpp_aligned_alloc(std::size_t __alignment, std::size_t __size) {30# if defined(_LIBCPP_MSVCRT_LIKE)31 return ::_aligned_malloc(__size, __alignment);32 33// Android only provides aligned_alloc when targeting API 28 or higher.34# elif !defined(__ANDROID__) || __ANDROID_API__ >= 2835 // aligned_alloc() requires that __size is a multiple of __alignment,36 // but for C++ [new.delete.general], only states "if the value of an37 // alignment argument passed to any of these functions is not a valid38 // alignment value, the behavior is undefined".39 // To handle calls such as ::operator new(1, std::align_val_t(128)), we40 // round __size up to the next multiple of __alignment.41 size_t __rounded_size = (__size + __alignment - 1) & ~(__alignment - 1);42 // Rounding up could have wrapped around to zero, so we have to add another43 // max() ternary to the actual call site to avoid succeeded in that case.44 return ::aligned_alloc(__alignment, __size > __rounded_size ? __size : __rounded_size);45# else46 void* __result = nullptr;47 (void)::posix_memalign(&__result, __alignment, __size);48 // If posix_memalign fails, __result is unmodified so we still return `nullptr`.49 return __result;50# endif51}52 53inline _LIBCPP_HIDE_FROM_ABI void __libcpp_aligned_free(void* __ptr) {54# if defined(_LIBCPP_MSVCRT_LIKE)55 ::_aligned_free(__ptr);56# else57 ::free(__ptr);58# endif59}60 61#endif // _LIBCPP_HAS_LIBRARY_ALIGNED_ALLOCATION62 63_LIBCPP_END_NAMESPACE_STD64 65#endif // _LIBCPP_SRC_ALIGNED_ALLOC_H66