1 // Allocator that wraps operator new -*- C++ -*- 2 3 // Copyright (C) 2001-2022 Free Software Foundation, Inc. 4 // 5 // This file is part of the GNU ISO C++ Library. This library is free 6 // software; you can redistribute it and/or modify it under the 7 // terms of the GNU General Public License as published by the 8 // Free Software Foundation; either version 3, or (at your option) 9 // any later version. 10 11 // This library is distributed in the hope that it will be useful, 12 // but WITHOUT ANY WARRANTY; without even the implied warranty of 13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 // GNU General Public License for more details. 15 16 // Under Section 7 of GPL version 3, you are granted additional 17 // permissions described in the GCC Runtime Library Exception, version 18 // 3.1, as published by the Free Software Foundation. 19 20 // You should have received a copy of the GNU General Public License and 21 // a copy of the GCC Runtime Library Exception along with this program; 22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 // <http://www.gnu.org/licenses/>. 24 25 /** @file bits/new_allocator.h 26 * This is an internal header file, included by other library headers. 27 * Do not attempt to use it directly. @headername{memory} 28 */ 29 30 #ifndef _STD_NEW_ALLOCATOR_H 31 #define _STD_NEW_ALLOCATOR_H 1 32 33 #include <bits/c++config.h> 34 #include <new> 35 #include <bits/functexcept.h> 36 #include <bits/move.h> 37 #if __cplusplus >= 201103L 38 #include <type_traits> 39 #endif 40 41 namespace std _GLIBCXX_VISIBILITY(default) 42 { 43 _GLIBCXX_BEGIN_NAMESPACE_VERSION 44 45 /** 46 * @brief An allocator that uses global `new`, as per C++03 [20.4.1]. 47 * @ingroup allocators 48 * 49 * This is precisely the allocator defined in the C++ Standard. 50 * - all allocation calls `operator new` 51 * - all deallocation calls `operator delete` 52 * 53 * This is the default base-class implementation of `std::allocator`, 54 * and is also the base-class of the `__gnu_cxx::new_allocator` extension. 55 * You should use either `std::allocator` or `__gnu_cxx::new_allocator` 56 * instead of using this directly. 57 * 58 * @tparam _Tp Type of allocated object. 59 * 60 * @headerfile memory 61 */ 62 template<typename _Tp> 63 class __new_allocator 64 { 65 public: 66 typedef _Tp value_type; 67 typedef std::size_t size_type; 68 typedef std::ptrdiff_t difference_type; 69 #if __cplusplus <= 201703L 70 typedef _Tp* pointer; 71 typedef const _Tp* const_pointer; 72 typedef _Tp& reference; 73 typedef const _Tp& const_reference; 74 75 template<typename _Tp1> 76 struct rebind 77 { typedef __new_allocator<_Tp1> other; }; 78 #endif 79 80 #if __cplusplus >= 201103L 81 // _GLIBCXX_RESOLVE_LIB_DEFECTS 82 // 2103. propagate_on_container_move_assignment 83 typedef std::true_type propagate_on_container_move_assignment; 84 #endif 85 86 _GLIBCXX20_CONSTEXPR 87 __new_allocator() _GLIBCXX_USE_NOEXCEPT { } 88 89 _GLIBCXX20_CONSTEXPR 90 __new_allocator(const __new_allocator&) _GLIBCXX_USE_NOEXCEPT { } 91 92 template<typename _Tp1> 93 _GLIBCXX20_CONSTEXPR 94 __new_allocator(const __new_allocator<_Tp1>&) _GLIBCXX_USE_NOEXCEPT { } 95 96 #if __cplusplus >= 201103L 97 __new_allocator& operator=(const __new_allocator&) = default; 98 #endif 99 100 #if __cplusplus <= 201703L 101 ~__new_allocator() _GLIBCXX_USE_NOEXCEPT { } 102 103 pointer 104 address(reference __x) const _GLIBCXX_NOEXCEPT 105 { return std::__addressof(__x); } 106 107 const_pointer 108 address(const_reference __x) const _GLIBCXX_NOEXCEPT 109 { return std::__addressof(__x); } 110 #endif 111 112 #if __has_builtin(__builtin_operator_new) >= 201802L 113 # define _GLIBCXX_OPERATOR_NEW __builtin_operator_new 114 # define _GLIBCXX_OPERATOR_DELETE __builtin_operator_delete 115 #else 116 # define _GLIBCXX_OPERATOR_NEW ::operator new 117 # define _GLIBCXX_OPERATOR_DELETE ::operator delete 118 #endif 119 120 // NB: __n is permitted to be 0. The C++ standard says nothing 121 // about what the return value is when __n == 0. 122 _GLIBCXX_NODISCARD _Tp* 123 allocate(size_type __n, const void* = static_cast<const void*>(0)) 124 { 125 #if __cplusplus >= 201103L 126 // _GLIBCXX_RESOLVE_LIB_DEFECTS 127 // 3308. std::allocator<void>().allocate(n) 128 static_assert(sizeof(_Tp) != 0, "cannot allocate incomplete types"); 129 #endif 130 131 if (__builtin_expect(__n > this->_M_max_size(), false)) 132 { 133 // _GLIBCXX_RESOLVE_LIB_DEFECTS 134 // 3190. allocator::allocate sometimes returns too little storage 135 if (__n > (std::size_t(-1) / sizeof(_Tp))) 136 std::__throw_bad_array_new_length(); 137 std::__throw_bad_alloc(); 138 } 139 140 #if __cpp_aligned_new 141 if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__) 142 { 143 std::align_val_t __al = std::align_val_t(alignof(_Tp)); 144 return static_cast<_Tp*>(_GLIBCXX_OPERATOR_NEW(__n * sizeof(_Tp), 145 __al)); 146 } 147 #endif 148 return static_cast<_Tp*>(_GLIBCXX_OPERATOR_NEW(__n * sizeof(_Tp))); 149 } 150 151 // __p is not permitted to be a null pointer. 152 void 153 deallocate(_Tp* __p, size_type __n __attribute__ ((__unused__))) 154 { 155 #if __cpp_sized_deallocation 156 # define _GLIBCXX_SIZED_DEALLOC(p, n) (p), (n) * sizeof(_Tp) 157 #else 158 # define _GLIBCXX_SIZED_DEALLOC(p, n) (p) 159 #endif 160 161 #if __cpp_aligned_new 162 if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__) 163 { 164 _GLIBCXX_OPERATOR_DELETE(_GLIBCXX_SIZED_DEALLOC(__p, __n), 165 std::align_val_t(alignof(_Tp))); 166 return; 167 } 168 #endif 169 _GLIBCXX_OPERATOR_DELETE(_GLIBCXX_SIZED_DEALLOC(__p, __n)); 170 } 171 172 #undef _GLIBCXX_SIZED_DEALLOC 173 #undef _GLIBCXX_OPERATOR_DELETE 174 #undef _GLIBCXX_OPERATOR_NEW 175 176 #if __cplusplus <= 201703L 177 size_type 178 max_size() const _GLIBCXX_USE_NOEXCEPT 179 { return _M_max_size(); } 180 181 #if __cplusplus >= 201103L 182 template<typename _Up, typename... _Args> 183 void 184 construct(_Up* __p, _Args&&... __args) 185 noexcept(std::is_nothrow_constructible<_Up, _Args...>::value) 186 { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); } 187 188 template<typename _Up> 189 void 190 destroy(_Up* __p) 191 noexcept(std::is_nothrow_destructible<_Up>::value) 192 { __p->~_Up(); } 193 #else 194 // _GLIBCXX_RESOLVE_LIB_DEFECTS 195 // 402. wrong new expression in [some_] allocator::construct 196 void 197 construct(pointer __p, const _Tp& __val) 198 { ::new((void *)__p) _Tp(__val); } 199 200 void 201 destroy(pointer __p) { __p->~_Tp(); } 202 #endif 203 #endif // ! C++20 204 205 template<typename _Up> 206 friend _GLIBCXX20_CONSTEXPR bool 207 operator==(const __new_allocator&, const __new_allocator<_Up>&) 208 _GLIBCXX_NOTHROW 209 { return true; } 210 211 #if __cpp_impl_three_way_comparison < 201907L 212 template<typename _Up> 213 friend _GLIBCXX20_CONSTEXPR bool 214 operator!=(const __new_allocator&, const __new_allocator<_Up>&) 215 _GLIBCXX_NOTHROW 216 { return false; } 217 #endif 218 219 private: 220 _GLIBCXX_CONSTEXPR size_type 221 _M_max_size() const _GLIBCXX_USE_NOEXCEPT 222 { 223 #if __PTRDIFF_MAX__ < __SIZE_MAX__ 224 return std::size_t(__PTRDIFF_MAX__) / sizeof(_Tp); 225 #else 226 return std::size_t(-1) / sizeof(_Tp); 227 #endif 228 } 229 }; 230 231 _GLIBCXX_END_NAMESPACE_VERSION 232 } // namespace 233 234 #endif 235