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_TEMPORARY_BUFFER_H 11 #define _LIBCPP___MEMORY_TEMPORARY_BUFFER_H 12 13 #include <__config> 14 #include <__utility/pair.h> 15 #include <cstddef> 16 #include <new> 17 18 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 19 # pragma GCC system_header 20 #endif 21 22 _LIBCPP_BEGIN_NAMESPACE_STD 23 24 template <class _Tp> 25 _LIBCPP_NODISCARD _LIBCPP_HIDE_FROM_ABI _LIBCPP_NO_CFI _LIBCPP_DEPRECATED_IN_CXX17 pair<_Tp*, ptrdiff_t> 26 get_temporary_buffer(ptrdiff_t __n) _NOEXCEPT { 27 pair<_Tp*, ptrdiff_t> __r(0, 0); 28 const ptrdiff_t __m = 29 (~ptrdiff_t(0) ^ ptrdiff_t(ptrdiff_t(1) << (sizeof(ptrdiff_t) * __CHAR_BIT__ - 1))) / sizeof(_Tp); 30 if (__n > __m) 31 __n = __m; 32 while (__n > 0) { 33 #if !defined(_LIBCPP_HAS_NO_ALIGNED_ALLOCATION) 34 if (__is_overaligned_for_new(_LIBCPP_ALIGNOF(_Tp))) { 35 align_val_t __al = align_val_t(_LIBCPP_ALIGNOF(_Tp)); 36 __r.first = static_cast<_Tp*>(::operator new(__n * sizeof(_Tp), __al, nothrow)); 37 } else { 38 __r.first = static_cast<_Tp*>(::operator new(__n * sizeof(_Tp), nothrow)); 39 } 40 #else 41 if (__is_overaligned_for_new(_LIBCPP_ALIGNOF(_Tp))) { 42 // Since aligned operator new is unavailable, return an empty 43 // buffer rather than one with invalid alignment. 44 return __r; 45 } 46 47 __r.first = static_cast<_Tp*>(::operator new(__n * sizeof(_Tp), nothrow)); 48 #endif 49 50 if (__r.first) { 51 __r.second = __n; 52 break; 53 } 54 __n /= 2; 55 } 56 return __r; 57 } 58 59 template <class _Tp> 60 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_DEPRECATED_IN_CXX17 void return_temporary_buffer(_Tp* __p) _NOEXCEPT { 61 std::__libcpp_deallocate_unsized((void*)__p, _LIBCPP_ALIGNOF(_Tp)); 62 } 63 64 struct __return_temporary_buffer { 65 _LIBCPP_SUPPRESS_DEPRECATED_PUSH 66 template <class _Tp> 67 _LIBCPP_HIDE_FROM_ABI void operator()(_Tp* __p) const { 68 std::return_temporary_buffer(__p); 69 } 70 _LIBCPP_SUPPRESS_DEPRECATED_POP 71 }; 72 73 _LIBCPP_END_NAMESPACE_STD 74 75 #endif // _LIBCPP___MEMORY_TEMPORARY_BUFFER_H 76