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 #include <stdexcept> 25 26 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 27 # pragma GCC system_header 28 #endif 29 30 _LIBCPP_BEGIN_NAMESPACE_STD 31 32 template <class _Tp> 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 { 40 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS) 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> struct _LIBCPP_DEPRECATED_IN_CXX17 rebind {typedef allocator<_Up> other;}; 47 #endif 48 }; 49 50 template <> 51 class _LIBCPP_TEMPLATE_VIS allocator<const void> 52 { 53 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS) 54 public: 55 _LIBCPP_DEPRECATED_IN_CXX17 typedef const void* pointer; 56 _LIBCPP_DEPRECATED_IN_CXX17 typedef const void* const_pointer; 57 _LIBCPP_DEPRECATED_IN_CXX17 typedef const void value_type; 58 59 template <class _Up> struct _LIBCPP_DEPRECATED_IN_CXX17 rebind {typedef allocator<_Up> other;}; 60 #endif 61 }; 62 #endif 63 64 // This class provides a non-trivial default constructor to the class that derives from it 65 // if the condition is satisfied. 66 // 67 // The second template parameter exists to allow giving a unique type to __non_trivial_if, 68 // which makes it possible to avoid breaking the ABI when making this a base class of an 69 // existing class. Without that, imagine we have classes D1 and D2, both of which used to 70 // have no base classes, but which now derive from __non_trivial_if. The layout of a class 71 // that inherits from both D1 and D2 will change because the two __non_trivial_if base 72 // classes are not allowed to share the same address. 73 // 74 // By making those __non_trivial_if base classes unique, we work around this problem and 75 // it is safe to start deriving from __non_trivial_if in existing classes. 76 template <bool _Cond, class _Unique> 77 struct __non_trivial_if { }; 78 79 template <class _Unique> 80 struct __non_trivial_if<true, _Unique> { 81 _LIBCPP_INLINE_VISIBILITY 82 _LIBCPP_CONSTEXPR __non_trivial_if() _NOEXCEPT { } 83 }; 84 85 // allocator 86 // 87 // Note: For ABI compatibility between C++20 and previous standards, we make 88 // allocator<void> trivial in C++20. 89 90 template <class _Tp> 91 class _LIBCPP_TEMPLATE_VIS allocator 92 : private __non_trivial_if<!is_void<_Tp>::value, allocator<_Tp> > 93 { 94 static_assert(!is_volatile<_Tp>::value, "std::allocator does not support volatile types"); 95 public: 96 typedef size_t size_type; 97 typedef ptrdiff_t difference_type; 98 typedef _Tp value_type; 99 typedef true_type propagate_on_container_move_assignment; 100 typedef true_type is_always_equal; 101 102 _LIBCPP_CONSTEXPR_SINCE_CXX20 allocator() _NOEXCEPT = default; 103 104 template <class _Up> 105 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 106 allocator(const allocator<_Up>&) _NOEXCEPT { } 107 108 _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 109 _Tp* allocate(size_t __n) { 110 if (__n > allocator_traits<allocator>::max_size(*this)) 111 __throw_bad_array_new_length(); 112 if (__libcpp_is_constant_evaluated()) { 113 return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp))); 114 } else { 115 return static_cast<_Tp*>(_VSTD::__libcpp_allocate(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp))); 116 } 117 } 118 119 #if _LIBCPP_STD_VER >= 23 120 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr 121 allocation_result<_Tp*> allocate_at_least(size_t __n) { 122 return {allocate(__n), __n}; 123 } 124 #endif 125 126 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 127 void deallocate(_Tp* __p, size_t __n) _NOEXCEPT { 128 if (__libcpp_is_constant_evaluated()) { 129 ::operator delete(__p); 130 } else { 131 _VSTD::__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_INLINE_VISIBILITY 148 pointer address(reference __x) const _NOEXCEPT { 149 return _VSTD::addressof(__x); 150 } 151 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_INLINE_VISIBILITY 152 const_pointer address(const_reference __x) const _NOEXCEPT { 153 return _VSTD::addressof(__x); 154 } 155 156 _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY _LIBCPP_DEPRECATED_IN_CXX17 157 _Tp* allocate(size_t __n, const void*) { 158 return allocate(__n); 159 } 160 161 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_INLINE_VISIBILITY size_type max_size() const _NOEXCEPT { 162 return size_type(~0) / sizeof(_Tp); 163 } 164 165 template <class _Up, class... _Args> 166 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_INLINE_VISIBILITY 167 void construct(_Up* __p, _Args&&... __args) { 168 ::new ((void*)__p) _Up(_VSTD::forward<_Args>(__args)...); 169 } 170 171 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_INLINE_VISIBILITY 172 void destroy(pointer __p) { 173 __p->~_Tp(); 174 } 175 #endif 176 }; 177 178 template <class _Tp> 179 class _LIBCPP_TEMPLATE_VIS allocator<const _Tp> 180 : private __non_trivial_if<!is_void<_Tp>::value, allocator<const _Tp> > 181 { 182 static_assert(!is_volatile<_Tp>::value, "std::allocator does not support volatile types"); 183 public: 184 typedef size_t size_type; 185 typedef ptrdiff_t difference_type; 186 typedef const _Tp value_type; 187 typedef true_type propagate_on_container_move_assignment; 188 typedef true_type is_always_equal; 189 190 _LIBCPP_CONSTEXPR_SINCE_CXX20 allocator() _NOEXCEPT = default; 191 192 template <class _Up> 193 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 194 allocator(const allocator<_Up>&) _NOEXCEPT { } 195 196 _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 197 const _Tp* allocate(size_t __n) { 198 if (__n > allocator_traits<allocator>::max_size(*this)) 199 __throw_bad_array_new_length(); 200 if (__libcpp_is_constant_evaluated()) { 201 return static_cast<const _Tp*>(::operator new(__n * sizeof(_Tp))); 202 } else { 203 return static_cast<const _Tp*>(_VSTD::__libcpp_allocate(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp))); 204 } 205 } 206 207 #if _LIBCPP_STD_VER >= 23 208 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr 209 allocation_result<const _Tp*> allocate_at_least(size_t __n) { 210 return {allocate(__n), __n}; 211 } 212 #endif 213 214 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 215 void deallocate(const _Tp* __p, size_t __n) { 216 if (__libcpp_is_constant_evaluated()) { 217 ::operator delete(const_cast<_Tp*>(__p)); 218 } else { 219 _VSTD::__libcpp_deallocate((void*) const_cast<_Tp *>(__p), __n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp)); 220 } 221 } 222 223 // C++20 Removed members 224 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS) 225 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp* pointer; 226 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp* const_pointer; 227 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp& reference; 228 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp& const_reference; 229 230 template <class _Up> 231 struct _LIBCPP_DEPRECATED_IN_CXX17 rebind { 232 typedef allocator<_Up> other; 233 }; 234 235 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_INLINE_VISIBILITY 236 const_pointer address(const_reference __x) const _NOEXCEPT { 237 return _VSTD::addressof(__x); 238 } 239 240 _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY _LIBCPP_DEPRECATED_IN_CXX17 241 const _Tp* allocate(size_t __n, const void*) { 242 return allocate(__n); 243 } 244 245 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_INLINE_VISIBILITY size_type max_size() const _NOEXCEPT { 246 return size_type(~0) / sizeof(_Tp); 247 } 248 249 template <class _Up, class... _Args> 250 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_INLINE_VISIBILITY 251 void construct(_Up* __p, _Args&&... __args) { 252 ::new ((void*)__p) _Up(_VSTD::forward<_Args>(__args)...); 253 } 254 255 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_INLINE_VISIBILITY 256 void destroy(pointer __p) { 257 __p->~_Tp(); 258 } 259 #endif 260 }; 261 262 template <class _Tp, class _Up> 263 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 264 bool operator==(const allocator<_Tp>&, const allocator<_Up>&) _NOEXCEPT {return true;} 265 266 template <class _Tp, class _Up> 267 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 268 bool operator!=(const allocator<_Tp>&, const allocator<_Up>&) _NOEXCEPT {return false;} 269 270 _LIBCPP_END_NAMESPACE_STD 271 272 #endif // _LIBCPP___MEMORY_ALLOCATOR_H 273