libstdc++
memory
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1// <memory> -*- C++ -*-
2
3// Copyright (C) 2001-2020 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library. This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14// GNU General Public License for more details.
15
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23// <http://www.gnu.org/licenses/>.
24
25/*
26 * Copyright (c) 1997-1999
27 * Silicon Graphics Computer Systems, Inc.
28 *
29 * Permission to use, copy, modify, distribute and sell this software
30 * and its documentation for any purpose is hereby granted without fee,
31 * provided that the above copyright notice appear in all copies and
32 * that both that copyright notice and this permission notice appear
33 * in supporting documentation. Silicon Graphics makes no
34 * representations about the suitability of this software for any
35 * purpose. It is provided "as is" without express or implied warranty.
36 *
37 */
38
39/** @file include/memory
40 * This is a Standard C++ Library header.
41 * @ingroup memory
42 */
43
44#ifndef _GLIBCXX_MEMORY
45#define _GLIBCXX_MEMORY 1
46
47#pragma GCC system_header
48
49/**
50 * @defgroup memory Memory
51 * @ingroup utilities
52 *
53 * Components for memory allocation, deallocation, and management.
54 */
55
56/**
57 * @defgroup pointer_abstractions Pointer Abstractions
58 * @ingroup memory
59 *
60 * Smart pointers, etc.
61 */
62
63#include <bits/stl_algobase.h>
64#include <bits/allocator.h>
65#include <bits/stl_construct.h>
67#include <bits/stl_tempbuf.h>
70
71#if __cplusplus >= 201103L
72# include <exception> // std::exception
73# include <typeinfo> // std::type_info in get_deleter
74# include <iosfwd> // std::basic_ostream
75# include <ext/atomicity.h>
76# include <ext/concurrence.h>
77# include <bits/functexcept.h>
78# include <bits/stl_function.h> // std::less
79# include <bits/uses_allocator.h>
80# include <bits/alloc_traits.h>
81# include <type_traits>
82# include <debug/debug.h>
83# include <bits/unique_ptr.h>
84# include <bits/shared_ptr.h>
86# if _GLIBCXX_USE_DEPRECATED
87# include <backward/auto_ptr.h>
88# endif
89#else
90# include <backward/auto_ptr.h>
91#endif
92
93#if __cplusplus >= 201103L
94#include <cstdint>
95#if __cplusplus > 201703L
96# include <bit> // for has_single_bit
97# include <new> // for placement operator new
98# include <tuple> // for tuple, make_tuple, make_from_tuple
99#endif
100namespace std _GLIBCXX_VISIBILITY(default)
101{
102_GLIBCXX_BEGIN_NAMESPACE_VERSION
103
104/**
105 * @brief Fit aligned storage in buffer.
106 * @ingroup memory
107 *
108 * This function tries to fit @a __size bytes of storage with alignment
109 * @a __align into the buffer @a __ptr of size @a __space bytes. If such
110 * a buffer fits then @a __ptr is changed to point to the first byte of the
111 * aligned storage and @a __space is reduced by the bytes used for alignment.
112 *
113 * C++11 20.6.5 [ptr.align]
114 *
115 * @param __align A fundamental or extended alignment value.
116 * @param __size Size of the aligned storage required.
117 * @param __ptr Pointer to a buffer of @a __space bytes.
118 * @param __space Size of the buffer pointed to by @a __ptr.
119 * @return the updated pointer if the aligned storage fits, otherwise nullptr.
120 *
121 */
122inline void*
123align(size_t __align, size_t __size, void*& __ptr, size_t& __space) noexcept
124{
125#ifdef _GLIBCXX_USE_C99_STDINT_TR1
126 const auto __intptr = reinterpret_cast<uintptr_t>(__ptr);
127#else
128 // Cannot use std::uintptr_t so assume that std::size_t can be used instead.
129 static_assert(sizeof(size_t) >= sizeof(void*),
130 "std::size_t must be a suitable substitute for std::uintptr_t");
131 const auto __intptr = reinterpret_cast<unsigned long long>(__ptr);
132#endif
133 const auto __aligned = (__intptr - 1u + __align) & -__align;
134 const auto __diff = __aligned - __intptr;
135 if ((__size + __diff) > __space)
136 return nullptr;
137 else
138 {
139 __space -= __diff;
140 return __ptr = reinterpret_cast<void*>(__aligned);
141 }
142}
143
144/** @defgroup ptr_safety Pointer Safety and Garbage Collection
145 * @ingroup memory
146 *
147 * Utilities to assist with garbage collection in an implementation
148 * that supports <em>strict pointer safety</em>.
149 * This implementation only supports <em>relaxed pointer safety</em>
150 * and so these functions have no effect.
151 *
152 * C++11 20.6.4 [util.dynamic.safety], Pointer safety
153 *
154 * @{
155 */
156
157/// Constants representing the different types of pointer safety.
158enum class pointer_safety { relaxed, preferred, strict };
159
160/// Inform a garbage collector that an object is still in use.
161inline void
163
164/// Unregister an object previously registered with declare_reachable.
165template <typename _Tp>
166 inline _Tp*
167 undeclare_reachable(_Tp* __p) { return __p; }
168
169/// Inform a garbage collector that a region of memory need not be traced.
170inline void
171declare_no_pointers(char*, size_t) { }
172
173/// Unregister a range previously registered with declare_no_pointers.
174inline void
175undeclare_no_pointers(char*, size_t) { }
176
177/// The type of pointer safety supported by the implementation.
178inline pointer_safety
179get_pointer_safety() noexcept { return pointer_safety::relaxed; }
180// @}
181
182#if __cplusplus > 201703L
183 /** @brief Inform the compiler that a pointer is aligned.
184 *
185 * @tparam _Align An alignment value (i.e. a power of two)
186 * @tparam _Tp An object type
187 * @param __ptr A pointer that is aligned to _Align
188 * @ingroup memory
189 */
190 template<size_t _Align, class _Tp>
191 [[nodiscard,__gnu__::__always_inline__]]
192 constexpr _Tp* assume_aligned(_Tp* __ptr)
193 {
194 static_assert(std::has_single_bit(_Align));
195 _GLIBCXX_DEBUG_ASSERT((std::uintptr_t)__ptr % _Align == 0);
196 return static_cast<_Tp*>(__builtin_assume_aligned(__ptr, _Align));
197 }
198#endif // C++2a
199
200#if __cplusplus > 201703L
201 template<typename _Tp>
202 struct __is_pair : false_type { };
203 template<typename _Tp, typename _Up>
204 struct __is_pair<pair<_Tp, _Up>> : true_type { };
205 template<typename _Tp, typename _Up>
206 struct __is_pair<const pair<_Tp, _Up>> : true_type { };
207
208/** @addtogroup allocators
209 * @{
210 */
211 template<typename _Tp, typename __ = _Require<__not_<__is_pair<_Tp>>>,
212 typename _Alloc, typename... _Args>
213 constexpr auto
214 __uses_alloc_args(const _Alloc& __a, _Args&&... __args) noexcept
215 {
216 if constexpr (uses_allocator_v<remove_cv_t<_Tp>, _Alloc>)
217 {
218 if constexpr (is_constructible_v<_Tp, allocator_arg_t,
219 const _Alloc&, _Args...>)
220 {
221 return tuple<allocator_arg_t, const _Alloc&, _Args&&...>(
222 allocator_arg, __a, std::forward<_Args>(__args)...);
223 }
224 else
225 {
226 static_assert(is_constructible_v<_Tp, _Args..., const _Alloc&>,
227 "construction with an allocator must be possible"
228 " if uses_allocator is true");
229
230 return tuple<_Args&&..., const _Alloc&>(
231 std::forward<_Args>(__args)..., __a);
232 }
233 }
234 else
235 {
236 static_assert(is_constructible_v<_Tp, _Args...>);
237
238 return tuple<_Args&&...>(std::forward<_Args>(__args)...);
239 }
240 }
241
242#if __cpp_concepts
243 template<typename _Tp>
244 concept _Std_pair = __is_pair<_Tp>::value;
245#endif
246
247// This is a temporary workaround until -fconcepts is implied by -std=gnu++2a
248#if __cpp_concepts
249# define _GLIBCXX_STD_PAIR_CONSTRAINT(T) _Std_pair T
250# define _GLIBCXX_STD_PAIR_CONSTRAINT_(T) _Std_pair T
251#else
252# define _GLIBCXX_STD_PAIR_CONSTRAINT(T) \
253 typename T, typename __ = _Require<__is_pair<T>>
254# define _GLIBCXX_STD_PAIR_CONSTRAINT_(T) typename T, typename
255#endif
256
257 template<typename _Tp,
258#if ! __cpp_concepts
259 typename __ = _Require<__not_<__is_pair<_Tp>>>,
260#endif
261 typename _Alloc, typename... _Args>
262 constexpr auto
263 uses_allocator_construction_args(const _Alloc& __a,
264 _Args&&... __args) noexcept
265#if __cpp_concepts
266 requires (! _Std_pair<_Tp>)
267#endif
268 {
269 return std::__uses_alloc_args<_Tp>(__a, std::forward<_Args>(__args)...);
270 }
271
272 template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
273 typename _Tuple1, typename _Tuple2>
274 constexpr auto
275 uses_allocator_construction_args(const _Alloc& __a, piecewise_construct_t,
276 _Tuple1&& __x, _Tuple2&& __y) noexcept;
277
278 template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc>
279 constexpr auto
280 uses_allocator_construction_args(const _Alloc&) noexcept;
281
282 template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
283 typename _Up, typename _Vp>
284 constexpr auto
285 uses_allocator_construction_args(const _Alloc&, _Up&&, _Vp&&) noexcept;
286
287 template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
288 typename _Up, typename _Vp>
289 constexpr auto
290 uses_allocator_construction_args(const _Alloc&,
291 const pair<_Up, _Vp>&) noexcept;
292
293 template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
294 typename _Up, typename _Vp>
295 constexpr auto
296 uses_allocator_construction_args(const _Alloc&, pair<_Up, _Vp>&&) noexcept;
297
298 template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
299 typename _Tuple1, typename _Tuple2>
300 constexpr auto
301 uses_allocator_construction_args(const _Alloc& __a, piecewise_construct_t,
302 _Tuple1&& __x, _Tuple2&& __y) noexcept
303 {
304 using _Tp1 = typename _Tp::first_type;
305 using _Tp2 = typename _Tp::second_type;
306
307 return std::make_tuple(piecewise_construct,
308 std::apply([&__a](auto&&... __args1) {
309 return std::uses_allocator_construction_args<_Tp1>(
310 __a, std::forward<decltype(__args1)>(__args1)...);
311 }, std::forward<_Tuple1>(__x)),
312 std::apply([&__a](auto&&... __args2) {
313 return std::uses_allocator_construction_args<_Tp2>(
314 __a, std::forward<decltype(__args2)>(__args2)...);
315 }, std::forward<_Tuple2>(__y)));
316 }
317
318 template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc>
319 constexpr auto
320 uses_allocator_construction_args(const _Alloc& __a) noexcept
321 {
322 using _Tp1 = typename _Tp::first_type;
323 using _Tp2 = typename _Tp::second_type;
324
325 return std::make_tuple(piecewise_construct,
326 std::uses_allocator_construction_args<_Tp1>(__a),
327 std::uses_allocator_construction_args<_Tp2>(__a));
328 }
329
330 template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
331 typename _Up, typename _Vp>
332 constexpr auto
333 uses_allocator_construction_args(const _Alloc& __a, _Up&& __u, _Vp&& __v)
334 noexcept
335 {
336 using _Tp1 = typename _Tp::first_type;
337 using _Tp2 = typename _Tp::second_type;
338
339 return std::make_tuple(piecewise_construct,
340 std::uses_allocator_construction_args<_Tp1>(__a,
341 std::forward<_Up>(__u)),
342 std::uses_allocator_construction_args<_Tp2>(__a,
343 std::forward<_Vp>(__v)));
344 }
345
346 template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
347 typename _Up, typename _Vp>
348 constexpr auto
349 uses_allocator_construction_args(const _Alloc& __a,
350 const pair<_Up, _Vp>& __pr) noexcept
351 {
352 using _Tp1 = typename _Tp::first_type;
353 using _Tp2 = typename _Tp::second_type;
354
355 return std::make_tuple(piecewise_construct,
356 std::uses_allocator_construction_args<_Tp1>(__a, __pr.first),
357 std::uses_allocator_construction_args<_Tp2>(__a, __pr.second));
358 }
359
360 template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
361 typename _Up, typename _Vp>
362 constexpr auto
363 uses_allocator_construction_args(const _Alloc& __a,
364 pair<_Up, _Vp>&& __pr) noexcept
365 {
366 using _Tp1 = typename _Tp::first_type;
367 using _Tp2 = typename _Tp::second_type;
368
369 return std::make_tuple(piecewise_construct,
370 std::uses_allocator_construction_args<_Tp1>(__a,
371 std::move(__pr).first),
372 std::uses_allocator_construction_args<_Tp2>(__a,
373 std::move(__pr).second));
374 }
375
376 template<typename _Tp, typename _Alloc, typename... _Args>
377 inline _Tp
378 make_obj_using_allocator(const _Alloc& __a, _Args&&... __args)
379 {
380 return std::make_from_tuple<_Tp>(
381 std::uses_allocator_construction_args<_Tp>(__a,
382 std::forward<_Args>(__args)...));
383 }
384
385 template<typename _Tp, typename _Alloc, typename... _Args>
386 inline _Tp*
387 uninitialized_construct_using_allocator(_Tp* __p, const _Alloc& __a,
388 _Args&&... __args)
389 {
390 return std::apply([&](auto&&... __xs) {
391 return std::construct_at(__p, std::forward<decltype(__xs)>(__xs)...);
392 }, std::uses_allocator_construction_args<_Tp>(__a,
393 std::forward<_Args>(__args)...));
394 }
395// @}
396
397#endif // C++2a
398
399_GLIBCXX_END_NAMESPACE_VERSION
400} // namespace
401#endif // C++11
402
403#if __cplusplus > 201402L
404// Parallel STL algorithms
405# if _PSTL_EXECUTION_POLICIES_DEFINED
406// If <execution> has already been included, pull in implementations
407# include <pstl/glue_memory_impl.h>
408# else
409// Otherwise just pull in forward declarations
410# include <pstl/glue_memory_defs.h>
411# endif
412
413// Feature test macro for parallel algorithms
414# define __cpp_lib_parallel_algorithm 201603L
415#endif // C++17
416
417#endif /* _GLIBCXX_MEMORY */
void * align(size_t __align, size_t __size, void *&__ptr, size_t &__space) noexcept
Fit aligned storage in buffer.
Definition: memory:123
void declare_reachable(void *)
Inform a garbage collector that an object is still in use.
Definition: memory:162
pointer_safety get_pointer_safety() noexcept
The type of pointer safety supported by the implementation.
Definition: memory:179
void undeclare_no_pointers(char *, size_t)
Unregister a range previously registered with declare_no_pointers.
Definition: memory:175
void declare_no_pointers(char *, size_t)
Inform a garbage collector that a region of memory need not be traced.
Definition: memory:171
pointer_safety
Constants representing the different types of pointer safety.
Definition: memory:158
_Tp * undeclare_reachable(_Tp *__p)
Unregister an object previously registered with declare_reachable.
Definition: memory:167
integral_constant< bool, true > true_type
The type used as a compile-time boolean with true value.
Definition: type_traits:75
integral_constant< bool, false > false_type
The type used as a compile-time boolean with false value.
Definition: type_traits:78
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:101
constexpr piecewise_construct_t piecewise_construct
Tag for piecewise construction of std::pair objects.
Definition: stl_pair.h:82
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition: move.h:76
ISO C++ entities toplevel namespace is std.