xref: /freebsd/contrib/llvm-project/libcxx/include/__memory/allocator.h (revision e1e636193db45630c7881246d25902e57c43d24e)
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 defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS) && !defined(_LIBCPP_DISABLE_DEPRECATION_WARNINGS)
35 #  pragma clang deprecated(                                                                                            \
36       _LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS,                                                                  \
37       "_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS is deprecated in LLVM 18 and will be removed in LLVM 19")
38 #endif
39 
40 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_VOID_SPECIALIZATION)
41 // These specializations shouldn't be marked _LIBCPP_DEPRECATED_IN_CXX17.
42 // Specializing allocator<void> is deprecated, but not using it.
43 template <>
44 class _LIBCPP_TEMPLATE_VIS allocator<void> {
45 #  if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS)
46 
47 public:
48   _LIBCPP_DEPRECATED_IN_CXX17 typedef void* pointer;
49   _LIBCPP_DEPRECATED_IN_CXX17 typedef const void* const_pointer;
50   _LIBCPP_DEPRECATED_IN_CXX17 typedef void value_type;
51 
52   template <class _Up>
53   struct _LIBCPP_DEPRECATED_IN_CXX17 rebind {
54     typedef allocator<_Up> other;
55   };
56 #  endif
57 };
58 
59 template <>
60 class _LIBCPP_TEMPLATE_VIS allocator<const void> {
61 #  if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS)
62 
63 public:
64   _LIBCPP_DEPRECATED_IN_CXX17 typedef const void* pointer;
65   _LIBCPP_DEPRECATED_IN_CXX17 typedef const void* const_pointer;
66   _LIBCPP_DEPRECATED_IN_CXX17 typedef const void value_type;
67 
68   template <class _Up>
69   struct _LIBCPP_DEPRECATED_IN_CXX17 rebind {
70     typedef allocator<_Up> other;
71   };
72 #  endif
73 };
74 #endif
75 
76 // This class provides a non-trivial default constructor to the class that derives from it
77 // if the condition is satisfied.
78 //
79 // The second template parameter exists to allow giving a unique type to __non_trivial_if,
80 // which makes it possible to avoid breaking the ABI when making this a base class of an
81 // existing class. Without that, imagine we have classes D1 and D2, both of which used to
82 // have no base classes, but which now derive from __non_trivial_if. The layout of a class
83 // that inherits from both D1 and D2 will change because the two __non_trivial_if base
84 // classes are not allowed to share the same address.
85 //
86 // By making those __non_trivial_if base classes unique, we work around this problem and
87 // it is safe to start deriving from __non_trivial_if in existing classes.
88 template <bool _Cond, class _Unique>
89 struct __non_trivial_if {};
90 
91 template <class _Unique>
92 struct __non_trivial_if<true, _Unique> {
93   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __non_trivial_if() _NOEXCEPT {}
94 };
95 
96 // allocator
97 //
98 // Note: For ABI compatibility between C++20 and previous standards, we make
99 //       allocator<void> trivial in C++20.
100 
101 template <class _Tp>
102 class _LIBCPP_TEMPLATE_VIS allocator : private __non_trivial_if<!is_void<_Tp>::value, allocator<_Tp> > {
103   static_assert(!is_volatile<_Tp>::value, "std::allocator does not support volatile types");
104 
105 public:
106   typedef size_t size_type;
107   typedef ptrdiff_t difference_type;
108   typedef _Tp value_type;
109   typedef true_type propagate_on_container_move_assignment;
110 #if _LIBCPP_STD_VER <= 23 || defined(_LIBCPP_ENABLE_CXX26_REMOVED_ALLOCATOR_MEMBERS)
111   _LIBCPP_DEPRECATED_IN_CXX23 typedef true_type is_always_equal;
112 #endif
113 
114   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 allocator() _NOEXCEPT = default;
115 
116   template <class _Up>
117   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 allocator(const allocator<_Up>&) _NOEXCEPT {}
118 
119   _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp* allocate(size_t __n) {
120     if (__n > allocator_traits<allocator>::max_size(*this))
121       __throw_bad_array_new_length();
122     if (__libcpp_is_constant_evaluated()) {
123       return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp)));
124     } else {
125       return static_cast<_Tp*>(std::__libcpp_allocate(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp)));
126     }
127   }
128 
129 #if _LIBCPP_STD_VER >= 23
130   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr allocation_result<_Tp*> allocate_at_least(size_t __n) {
131     return {allocate(__n), __n};
132   }
133 #endif
134 
135   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void deallocate(_Tp* __p, size_t __n) _NOEXCEPT {
136     if (__libcpp_is_constant_evaluated()) {
137       ::operator delete(__p);
138     } else {
139       std::__libcpp_deallocate((void*)__p, __n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp));
140     }
141   }
142 
143   // C++20 Removed members
144 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS)
145   _LIBCPP_DEPRECATED_IN_CXX17 typedef _Tp* pointer;
146   _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp* const_pointer;
147   _LIBCPP_DEPRECATED_IN_CXX17 typedef _Tp& reference;
148   _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp& const_reference;
149 
150   template <class _Up>
151   struct _LIBCPP_DEPRECATED_IN_CXX17 rebind {
152     typedef allocator<_Up> other;
153   };
154 
155   _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI pointer address(reference __x) const _NOEXCEPT {
156     return std::addressof(__x);
157   }
158   _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI const_pointer address(const_reference __x) const _NOEXCEPT {
159     return std::addressof(__x);
160   }
161 
162   _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DEPRECATED_IN_CXX17 _Tp*
163   allocate(size_t __n, const void*) {
164     return allocate(__n);
165   }
166 
167   _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT {
168     return size_type(~0) / sizeof(_Tp);
169   }
170 
171   template <class _Up, class... _Args>
172   _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI void construct(_Up* __p, _Args&&... __args) {
173     ::new ((void*)__p) _Up(std::forward<_Args>(__args)...);
174   }
175 
176   _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI void destroy(pointer __p) { __p->~_Tp(); }
177 #endif
178 };
179 
180 template <class _Tp>
181 class _LIBCPP_TEMPLATE_VIS allocator<const _Tp>
182     : private __non_trivial_if<!is_void<_Tp>::value, allocator<const _Tp> > {
183   static_assert(!is_volatile<_Tp>::value, "std::allocator does not support volatile types");
184 
185 public:
186   typedef size_t size_type;
187   typedef ptrdiff_t difference_type;
188   typedef const _Tp value_type;
189   typedef true_type propagate_on_container_move_assignment;
190 #if _LIBCPP_STD_VER <= 23 || defined(_LIBCPP_ENABLE_CXX26_REMOVED_ALLOCATOR_MEMBERS)
191   _LIBCPP_DEPRECATED_IN_CXX23 typedef true_type is_always_equal;
192 #endif
193 
194   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 allocator() _NOEXCEPT = default;
195 
196   template <class _Up>
197   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 allocator(const allocator<_Up>&) _NOEXCEPT {}
198 
199   _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const _Tp* allocate(size_t __n) {
200     if (__n > allocator_traits<allocator>::max_size(*this))
201       __throw_bad_array_new_length();
202     if (__libcpp_is_constant_evaluated()) {
203       return static_cast<const _Tp*>(::operator new(__n * sizeof(_Tp)));
204     } else {
205       return static_cast<const _Tp*>(std::__libcpp_allocate(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp)));
206     }
207   }
208 
209 #if _LIBCPP_STD_VER >= 23
210   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr allocation_result<const _Tp*> allocate_at_least(size_t __n) {
211     return {allocate(__n), __n};
212   }
213 #endif
214 
215   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void deallocate(const _Tp* __p, size_t __n) {
216     if (__libcpp_is_constant_evaluated()) {
217       ::operator delete(const_cast<_Tp*>(__p));
218     } else {
219       std::__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_HIDE_FROM_ABI const_pointer address(const_reference __x) const _NOEXCEPT {
236     return std::addressof(__x);
237   }
238 
239   _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DEPRECATED_IN_CXX17 const _Tp*
240   allocate(size_t __n, const void*) {
241     return allocate(__n);
242   }
243 
244   _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT {
245     return size_type(~0) / sizeof(_Tp);
246   }
247 
248   template <class _Up, class... _Args>
249   _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI void construct(_Up* __p, _Args&&... __args) {
250     ::new ((void*)__p) _Up(std::forward<_Args>(__args)...);
251   }
252 
253   _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI void destroy(pointer __p) { __p->~_Tp(); }
254 #endif
255 };
256 
257 template <class _Tp, class _Up>
258 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool
259 operator==(const allocator<_Tp>&, const allocator<_Up>&) _NOEXCEPT {
260   return true;
261 }
262 
263 #if _LIBCPP_STD_VER <= 17
264 
265 template <class _Tp, class _Up>
266 inline _LIBCPP_HIDE_FROM_ABI bool operator!=(const allocator<_Tp>&, const allocator<_Up>&) _NOEXCEPT {
267   return false;
268 }
269 
270 #endif
271 
272 _LIBCPP_END_NAMESPACE_STD
273 
274 #endif // _LIBCPP___MEMORY_ALLOCATOR_H
275