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_const.h>
18#include <__type_traits/is_constant_evaluated.h>
19#include <__type_traits/is_same.h>
20#include <__type_traits/is_void.h>
21#include <__type_traits/is_volatile.h>
22#include <__utility/forward.h>
23#include <cstddef>
24#include <new>
25
26#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
27# pragma GCC system_header
28#endif
29
30_LIBCPP_BEGIN_NAMESPACE_STD
31
32template <class _Tp>
33class allocator;
34
35#if _LIBCPP_STD_VER <= 17
36// These specializations shouldn't be marked _LIBCPP_DEPRECATED_IN_CXX17.
37// Specializing allocator<void> is deprecated, but not using it.
38template <>
39class _LIBCPP_TEMPLATE_VIS allocator<void> {
40public:
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>
46 struct _LIBCPP_DEPRECATED_IN_CXX17 rebind {
47 typedef allocator<_Up> other;
48 };
49};
50
51// TODO(LLVM 20): Remove the escape hatch
52# ifdef _LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST
53template <>
54class _LIBCPP_TEMPLATE_VIS allocator<const void> {
55public:
56 _LIBCPP_DEPRECATED_IN_CXX17 typedef const void* pointer;
57 _LIBCPP_DEPRECATED_IN_CXX17 typedef const void* const_pointer;
58 _LIBCPP_DEPRECATED_IN_CXX17 typedef const void value_type;
59
60 template <class _Up>
61 struct _LIBCPP_DEPRECATED_IN_CXX17 rebind {
62 typedef allocator<_Up> other;
63 };
64};
65# endif // _LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST
66#endif // _LIBCPP_STD_VER <= 17
67
68// This class provides a non-trivial default constructor to the class that derives from it
69// if the condition is satisfied.
70//
71// The second template parameter exists to allow giving a unique type to __non_trivial_if,
72// which makes it possible to avoid breaking the ABI when making this a base class of an
73// existing class. Without that, imagine we have classes D1 and D2, both of which used to
74// have no base classes, but which now derive from __non_trivial_if. The layout of a class
75// that inherits from both D1 and D2 will change because the two __non_trivial_if base
76// classes are not allowed to share the same address.
77//
78// By making those __non_trivial_if base classes unique, we work around this problem and
79// it is safe to start deriving from __non_trivial_if in existing classes.
80template <bool _Cond, class _Unique>
81struct __non_trivial_if {};
82
83template <class _Unique>
84struct __non_trivial_if<true, _Unique> {
85 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __non_trivial_if() _NOEXCEPT {}
86};
87
88// allocator
89//
90// Note: For ABI compatibility between C++20 and previous standards, we make
91// allocator<void> trivial in C++20.
92
93template <class _Tp>
94class _LIBCPP_TEMPLATE_VIS allocator : private __non_trivial_if<!is_void<_Tp>::value, allocator<_Tp> > {
95 static_assert(!is_const<_Tp>::value, "std::allocator does not support const types");
96 static_assert(!is_volatile<_Tp>::value, "std::allocator does not support volatile types");
97
98public:
99 typedef size_t size_type;
100 typedef ptrdiff_t difference_type;
101 typedef _Tp value_type;
102 typedef true_type propagate_on_container_move_assignment;
103#if _LIBCPP_STD_VER <= 23 || defined(_LIBCPP_ENABLE_CXX26_REMOVED_ALLOCATOR_MEMBERS)
104 _LIBCPP_DEPRECATED_IN_CXX23 typedef true_type is_always_equal;
105#endif
106
107 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 allocator() _NOEXCEPT = default;
108
109 template <class _Up>
110 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 allocator(const allocator<_Up>&) _NOEXCEPT {}
111
112 _LIBCPP_NODISCARD _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp* allocate(size_t __n) {
113 if (__n > allocator_traits<allocator>::max_size(*this))
114 __throw_bad_array_new_length();
115 if (__libcpp_is_constant_evaluated()) {
116 return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp)));
117 } else {
118 return static_cast<_Tp*>(std::__libcpp_allocate(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp)));
119 }
120 }
121
122#if _LIBCPP_STD_VER >= 23
123 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr allocation_result<_Tp*> allocate_at_least(size_t __n) {
124 return {allocate(__n), __n};
125 }
126#endif
127
128 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void deallocate(_Tp* __p, size_t __n) _NOEXCEPT {
129 if (__libcpp_is_constant_evaluated()) {
130 ::operator delete(__p);
131 } else {
132 std::__libcpp_deallocate((void*)__p, __n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp));
133 }
134 }
135
136 // C++20 Removed members
137#if _LIBCPP_STD_VER <= 17
138 _LIBCPP_DEPRECATED_IN_CXX17 typedef _Tp* pointer;
139 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp* const_pointer;
140 _LIBCPP_DEPRECATED_IN_CXX17 typedef _Tp& reference;
141 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp& const_reference;
142
143 template <class _Up>
144 struct _LIBCPP_DEPRECATED_IN_CXX17 rebind {
145 typedef allocator<_Up> other;
146 };
147
148 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI pointer address(reference __x) const _NOEXCEPT {
149 return std::addressof(__x);
150 }
151 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI const_pointer address(const_reference __x) const _NOEXCEPT {
152 return std::addressof(__x);
153 }
154
155 _LIBCPP_NODISCARD _LIBCPP_HIDE_FROM_ABI _LIBCPP_DEPRECATED_IN_CXX17 _Tp* 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// TODO(LLVM 20): Remove the escape hatch
173#ifdef _LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST
174template <class _Tp>
175class _LIBCPP_TEMPLATE_VIS allocator<const _Tp>
176 : private __non_trivial_if<!is_void<_Tp>::value, allocator<const _Tp> > {
177 static_assert(!is_volatile<_Tp>::value, "std::allocator does not support volatile types");
178
179public:
180 typedef size_t size_type;
181 typedef ptrdiff_t difference_type;
182 typedef const _Tp value_type;
183 typedef true_type propagate_on_container_move_assignment;
184# if _LIBCPP_STD_VER <= 23 || defined(_LIBCPP_ENABLE_CXX26_REMOVED_ALLOCATOR_MEMBERS)
185 _LIBCPP_DEPRECATED_IN_CXX23 typedef true_type is_always_equal;
186# endif
187
188 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 allocator() _NOEXCEPT = default;
189
190 template <class _Up>
191 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 allocator(const allocator<_Up>&) _NOEXCEPT {}
192
193 _LIBCPP_NODISCARD _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const _Tp* allocate(size_t __n) {
194 if (__n > allocator_traits<allocator>::max_size(*this))
195 __throw_bad_array_new_length();
196 if (__libcpp_is_constant_evaluated()) {
197 return static_cast<const _Tp*>(::operator new(__n * sizeof(_Tp)));
198 } else {
199 return static_cast<const _Tp*>(std::__libcpp_allocate(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp)));
200 }
201 }
202
203# if _LIBCPP_STD_VER >= 23
204 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr allocation_result<const _Tp*> allocate_at_least(size_t __n) {
205 return {allocate(__n), __n};
206 }
207# endif
208
209 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void deallocate(const _Tp* __p, size_t __n) {
210 if (__libcpp_is_constant_evaluated()) {
211 ::operator delete(const_cast<_Tp*>(__p));
212 } else {
213 std::__libcpp_deallocate((void*)const_cast<_Tp*>(__p), __n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp));
214 }
215 }
216
217 // C++20 Removed members
218# if _LIBCPP_STD_VER <= 17
219 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp* pointer;
220 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp* const_pointer;
221 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp& reference;
222 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp& const_reference;
223
224 template <class _Up>
225 struct _LIBCPP_DEPRECATED_IN_CXX17 rebind {
226 typedef allocator<_Up> other;
227 };
228
229 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI const_pointer address(const_reference __x) const _NOEXCEPT {
230 return std::addressof(__x);
231 }
232
233 _LIBCPP_NODISCARD _LIBCPP_HIDE_FROM_ABI _LIBCPP_DEPRECATED_IN_CXX17 const _Tp* allocate(size_t __n, const void*) {
234 return allocate(__n);
235 }
236
237 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT {
238 return size_type(~0) / sizeof(_Tp);
239 }
240
241 template <class _Up, class... _Args>
242 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI void construct(_Up* __p, _Args&&... __args) {
243 ::new ((void*)__p) _Up(std::forward<_Args>(__args)...);
244 }
245
246 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI void destroy(pointer __p) { __p->~_Tp(); }
247# endif
248};
249#endif // _LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST
250
251template <class _Tp, class _Up>
252inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool
253operator==(const allocator<_Tp>&, const allocator<_Up>&) _NOEXCEPT {
254 return true;
255}
256
257#if _LIBCPP_STD_VER <= 17
258
259template <class _Tp, class _Up>
260inline _LIBCPP_HIDE_FROM_ABI bool operator!=(const allocator<_Tp>&, const allocator<_Up>&) _NOEXCEPT {
261 return false;
262}
263
264#endif
265
266_LIBCPP_END_NAMESPACE_STD
267
268#endif // _LIBCPP___MEMORY_ALLOCATOR_H
269