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_ALLOCATOR_H 11 #define _LIBCPP___MEMORY_ALLOCATOR_H 12 13 #include <__config> 14 #include <__memory/addressof.h> 15 #include <__memory/allocate_at_least.h> 16 #include <__memory/allocator_traits.h> 17 #include <__type_traits/is_constant_evaluated.h> 18 #include <__type_traits/is_same.h> 19 #include <__type_traits/is_void.h> 20 #include <__type_traits/is_volatile.h> 21 #include <__utility/forward.h> 22 #include <cstddef> 23 #include <new> 24 25 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 26 # pragma GCC system_header 27 #endif 28 29 _LIBCPP_BEGIN_NAMESPACE_STD 30 31 template <class _Tp> 32 class allocator; 33 34 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_VOID_SPECIALIZATION) 35 // These specializations shouldn't be marked _LIBCPP_DEPRECATED_IN_CXX17. 36 // Specializing allocator<void> is deprecated, but not using it. 37 template <> 38 class _LIBCPP_TEMPLATE_VIS allocator<void> { 39 # if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS) 40 41 public: 42 _LIBCPP_DEPRECATED_IN_CXX17 typedef void* pointer; 43 _LIBCPP_DEPRECATED_IN_CXX17 typedef const void* const_pointer; 44 _LIBCPP_DEPRECATED_IN_CXX17 typedef void value_type; 45 46 template <class _Up> 47 struct _LIBCPP_DEPRECATED_IN_CXX17 rebind { 48 typedef allocator<_Up> other; 49 }; 50 # endif 51 }; 52 53 template <> 54 class _LIBCPP_TEMPLATE_VIS allocator<const void> { 55 # if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS) 56 57 public: 58 _LIBCPP_DEPRECATED_IN_CXX17 typedef const void* pointer; 59 _LIBCPP_DEPRECATED_IN_CXX17 typedef const void* const_pointer; 60 _LIBCPP_DEPRECATED_IN_CXX17 typedef const void value_type; 61 62 template <class _Up> 63 struct _LIBCPP_DEPRECATED_IN_CXX17 rebind { 64 typedef allocator<_Up> other; 65 }; 66 # endif 67 }; 68 #endif 69 70 // This class provides a non-trivial default constructor to the class that derives from it 71 // if the condition is satisfied. 72 // 73 // The second template parameter exists to allow giving a unique type to __non_trivial_if, 74 // which makes it possible to avoid breaking the ABI when making this a base class of an 75 // existing class. Without that, imagine we have classes D1 and D2, both of which used to 76 // have no base classes, but which now derive from __non_trivial_if. The layout of a class 77 // that inherits from both D1 and D2 will change because the two __non_trivial_if base 78 // classes are not allowed to share the same address. 79 // 80 // By making those __non_trivial_if base classes unique, we work around this problem and 81 // it is safe to start deriving from __non_trivial_if in existing classes. 82 template <bool _Cond, class _Unique> 83 struct __non_trivial_if {}; 84 85 template <class _Unique> 86 struct __non_trivial_if<true, _Unique> { 87 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __non_trivial_if() _NOEXCEPT {} 88 }; 89 90 // allocator 91 // 92 // Note: For ABI compatibility between C++20 and previous standards, we make 93 // allocator<void> trivial in C++20. 94 95 template <class _Tp> 96 class _LIBCPP_TEMPLATE_VIS allocator : private __non_trivial_if<!is_void<_Tp>::value, allocator<_Tp> > { 97 static_assert(!is_volatile<_Tp>::value, "std::allocator does not support volatile types"); 98 99 public: 100 typedef size_t size_type; 101 typedef ptrdiff_t difference_type; 102 typedef _Tp value_type; 103 typedef true_type propagate_on_container_move_assignment; 104 typedef true_type is_always_equal; 105 106 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 allocator() _NOEXCEPT = default; 107 108 template <class _Up> 109 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 allocator(const allocator<_Up>&) _NOEXCEPT {} 110 111 _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp* allocate(size_t __n) { 112 if (__n > allocator_traits<allocator>::max_size(*this)) 113 __throw_bad_array_new_length(); 114 if (__libcpp_is_constant_evaluated()) { 115 return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp))); 116 } else { 117 return static_cast<_Tp*>(std::__libcpp_allocate(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp))); 118 } 119 } 120 121 #if _LIBCPP_STD_VER >= 23 122 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr allocation_result<_Tp*> allocate_at_least(size_t __n) { 123 return {allocate(__n), __n}; 124 } 125 #endif 126 127 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void deallocate(_Tp* __p, size_t __n) _NOEXCEPT { 128 if (__libcpp_is_constant_evaluated()) { 129 ::operator delete(__p); 130 } else { 131 std::__libcpp_deallocate((void*)__p, __n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp)); 132 } 133 } 134 135 // C++20 Removed members 136 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS) 137 _LIBCPP_DEPRECATED_IN_CXX17 typedef _Tp* pointer; 138 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp* const_pointer; 139 _LIBCPP_DEPRECATED_IN_CXX17 typedef _Tp& reference; 140 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp& const_reference; 141 142 template <class _Up> 143 struct _LIBCPP_DEPRECATED_IN_CXX17 rebind { 144 typedef allocator<_Up> other; 145 }; 146 147 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI pointer address(reference __x) const _NOEXCEPT { 148 return std::addressof(__x); 149 } 150 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI const_pointer address(const_reference __x) const _NOEXCEPT { 151 return std::addressof(__x); 152 } 153 154 _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DEPRECATED_IN_CXX17 _Tp* 155 allocate(size_t __n, const void*) { 156 return allocate(__n); 157 } 158 159 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT { 160 return size_type(~0) / sizeof(_Tp); 161 } 162 163 template <class _Up, class... _Args> 164 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI void construct(_Up* __p, _Args&&... __args) { 165 ::new ((void*)__p) _Up(std::forward<_Args>(__args)...); 166 } 167 168 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI void destroy(pointer __p) { __p->~_Tp(); } 169 #endif 170 }; 171 172 template <class _Tp> 173 class _LIBCPP_TEMPLATE_VIS allocator<const _Tp> 174 : private __non_trivial_if<!is_void<_Tp>::value, allocator<const _Tp> > { 175 static_assert(!is_volatile<_Tp>::value, "std::allocator does not support volatile types"); 176 177 public: 178 typedef size_t size_type; 179 typedef ptrdiff_t difference_type; 180 typedef const _Tp value_type; 181 typedef true_type propagate_on_container_move_assignment; 182 typedef true_type is_always_equal; 183 184 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 allocator() _NOEXCEPT = default; 185 186 template <class _Up> 187 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 allocator(const allocator<_Up>&) _NOEXCEPT {} 188 189 _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const _Tp* allocate(size_t __n) { 190 if (__n > allocator_traits<allocator>::max_size(*this)) 191 __throw_bad_array_new_length(); 192 if (__libcpp_is_constant_evaluated()) { 193 return static_cast<const _Tp*>(::operator new(__n * sizeof(_Tp))); 194 } else { 195 return static_cast<const _Tp*>(std::__libcpp_allocate(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp))); 196 } 197 } 198 199 #if _LIBCPP_STD_VER >= 23 200 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr allocation_result<const _Tp*> allocate_at_least(size_t __n) { 201 return {allocate(__n), __n}; 202 } 203 #endif 204 205 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void deallocate(const _Tp* __p, size_t __n) { 206 if (__libcpp_is_constant_evaluated()) { 207 ::operator delete(const_cast<_Tp*>(__p)); 208 } else { 209 std::__libcpp_deallocate((void*)const_cast<_Tp*>(__p), __n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp)); 210 } 211 } 212 213 // C++20 Removed members 214 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS) 215 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp* pointer; 216 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp* const_pointer; 217 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp& reference; 218 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp& const_reference; 219 220 template <class _Up> 221 struct _LIBCPP_DEPRECATED_IN_CXX17 rebind { 222 typedef allocator<_Up> other; 223 }; 224 225 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI const_pointer address(const_reference __x) const _NOEXCEPT { 226 return std::addressof(__x); 227 } 228 229 _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DEPRECATED_IN_CXX17 const _Tp* 230 allocate(size_t __n, const void*) { 231 return allocate(__n); 232 } 233 234 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT { 235 return size_type(~0) / sizeof(_Tp); 236 } 237 238 template <class _Up, class... _Args> 239 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI void construct(_Up* __p, _Args&&... __args) { 240 ::new ((void*)__p) _Up(std::forward<_Args>(__args)...); 241 } 242 243 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI void destroy(pointer __p) { __p->~_Tp(); } 244 #endif 245 }; 246 247 template <class _Tp, class _Up> 248 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool 249 operator==(const allocator<_Tp>&, const allocator<_Up>&) _NOEXCEPT { 250 return true; 251 } 252 253 #if _LIBCPP_STD_VER <= 17 254 255 template <class _Tp, class _Up> 256 inline _LIBCPP_HIDE_FROM_ABI bool operator!=(const allocator<_Tp>&, const allocator<_Up>&) _NOEXCEPT { 257 return false; 258 } 259 260 #endif 261 262 _LIBCPP_END_NAMESPACE_STD 263 264 #endif // _LIBCPP___MEMORY_ALLOCATOR_H 265