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/allocate_at_least.h> 15 #include <__memory/allocator_traits.h> 16 #include <__type_traits/is_constant_evaluated.h> 17 #include <__type_traits/is_same.h> 18 #include <__type_traits/is_void.h> 19 #include <__type_traits/is_volatile.h> 20 #include <__utility/forward.h> 21 #include <cstddef> 22 #include <new> 23 #include <stdexcept> 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> class allocator; 32 33 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_VOID_SPECIALIZATION) 34 // These specializations shouldn't be marked _LIBCPP_DEPRECATED_IN_CXX17. 35 // Specializing allocator<void> is deprecated, but not using it. 36 template <> 37 class _LIBCPP_TEMPLATE_VIS allocator<void> 38 { 39 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS) 40 public: 41 _LIBCPP_DEPRECATED_IN_CXX17 typedef void* pointer; 42 _LIBCPP_DEPRECATED_IN_CXX17 typedef const void* const_pointer; 43 _LIBCPP_DEPRECATED_IN_CXX17 typedef void value_type; 44 45 template <class _Up> struct _LIBCPP_DEPRECATED_IN_CXX17 rebind {typedef allocator<_Up> other;}; 46 #endif 47 }; 48 49 template <> 50 class _LIBCPP_TEMPLATE_VIS allocator<const void> 51 { 52 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS) 53 public: 54 _LIBCPP_DEPRECATED_IN_CXX17 typedef const void* pointer; 55 _LIBCPP_DEPRECATED_IN_CXX17 typedef const void* const_pointer; 56 _LIBCPP_DEPRECATED_IN_CXX17 typedef const void value_type; 57 58 template <class _Up> struct _LIBCPP_DEPRECATED_IN_CXX17 rebind {typedef allocator<_Up> other;}; 59 #endif 60 }; 61 #endif 62 63 // This class provides a non-trivial default constructor to the class that derives from it 64 // if the condition is satisfied. 65 // 66 // The second template parameter exists to allow giving a unique type to __non_trivial_if, 67 // which makes it possible to avoid breaking the ABI when making this a base class of an 68 // existing class. Without that, imagine we have classes D1 and D2, both of which used to 69 // have no base classes, but which now derive from __non_trivial_if. The layout of a class 70 // that inherits from both D1 and D2 will change because the two __non_trivial_if base 71 // classes are not allowed to share the same address. 72 // 73 // By making those __non_trivial_if base classes unique, we work around this problem and 74 // it is safe to start deriving from __non_trivial_if in existing classes. 75 template <bool _Cond, class _Unique> 76 struct __non_trivial_if { }; 77 78 template <class _Unique> 79 struct __non_trivial_if<true, _Unique> { 80 _LIBCPP_INLINE_VISIBILITY 81 _LIBCPP_CONSTEXPR __non_trivial_if() _NOEXCEPT { } 82 }; 83 84 // allocator 85 // 86 // Note: For ABI compatibility between C++20 and previous standards, we make 87 // allocator<void> trivial in C++20. 88 89 template <class _Tp> 90 class _LIBCPP_TEMPLATE_VIS allocator 91 : private __non_trivial_if<!is_void<_Tp>::value, allocator<_Tp> > 92 { 93 static_assert(!is_volatile<_Tp>::value, "std::allocator does not support volatile types"); 94 public: 95 typedef size_t size_type; 96 typedef ptrdiff_t difference_type; 97 typedef _Tp value_type; 98 typedef true_type propagate_on_container_move_assignment; 99 typedef true_type is_always_equal; 100 101 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 102 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 > 20 120 [[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_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 191 allocator() _NOEXCEPT = default; 192 193 template <class _Up> 194 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 195 allocator(const allocator<_Up>&) _NOEXCEPT { } 196 197 _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 198 const _Tp* allocate(size_t __n) { 199 if (__n > allocator_traits<allocator>::max_size(*this)) 200 __throw_bad_array_new_length(); 201 if (__libcpp_is_constant_evaluated()) { 202 return static_cast<const _Tp*>(::operator new(__n * sizeof(_Tp))); 203 } else { 204 return static_cast<const _Tp*>(_VSTD::__libcpp_allocate(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp))); 205 } 206 } 207 208 #if _LIBCPP_STD_VER > 20 209 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr 210 allocation_result<const _Tp*> allocate_at_least(size_t __n) { 211 return {allocate(__n), __n}; 212 } 213 #endif 214 215 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 216 void deallocate(const _Tp* __p, size_t __n) { 217 if (__libcpp_is_constant_evaluated()) { 218 ::operator delete(const_cast<_Tp*>(__p)); 219 } else { 220 _VSTD::__libcpp_deallocate((void*) const_cast<_Tp *>(__p), __n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp)); 221 } 222 } 223 224 // C++20 Removed members 225 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS) 226 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp* pointer; 227 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp* const_pointer; 228 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp& reference; 229 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp& const_reference; 230 231 template <class _Up> 232 struct _LIBCPP_DEPRECATED_IN_CXX17 rebind { 233 typedef allocator<_Up> other; 234 }; 235 236 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_INLINE_VISIBILITY 237 const_pointer address(const_reference __x) const _NOEXCEPT { 238 return _VSTD::addressof(__x); 239 } 240 241 _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY _LIBCPP_DEPRECATED_IN_CXX17 242 const _Tp* allocate(size_t __n, const void*) { 243 return allocate(__n); 244 } 245 246 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_INLINE_VISIBILITY size_type max_size() const _NOEXCEPT { 247 return size_type(~0) / sizeof(_Tp); 248 } 249 250 template <class _Up, class... _Args> 251 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_INLINE_VISIBILITY 252 void construct(_Up* __p, _Args&&... __args) { 253 ::new ((void*)__p) _Up(_VSTD::forward<_Args>(__args)...); 254 } 255 256 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_INLINE_VISIBILITY 257 void destroy(pointer __p) { 258 __p->~_Tp(); 259 } 260 #endif 261 }; 262 263 template <class _Tp, class _Up> 264 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 265 bool operator==(const allocator<_Tp>&, const allocator<_Up>&) _NOEXCEPT {return true;} 266 267 template <class _Tp, class _Up> 268 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 269 bool operator!=(const allocator<_Tp>&, const allocator<_Up>&) _NOEXCEPT {return false;} 270 271 _LIBCPP_END_NAMESPACE_STD 272 273 #endif // _LIBCPP___MEMORY_ALLOCATOR_H 274