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>
66 #include <bits/stl_uninitialized.h>
67 #include <bits/stl_tempbuf.h>
68 #include <bits/stl_raw_storage_iter.h>
69 #include <bits/ranges_uninitialized.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>
85 # include <bits/shared_ptr_atomic.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
100 namespace 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  */
122 inline void*
123 align(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.
158 enum class pointer_safety { relaxed, preferred, strict };
159 
160 /// Inform a garbage collector that an object is still in use.
161 inline void
162 declare_reachable(void*) { }
163 
164 /// Unregister an object previously registered with declare_reachable.
165 template <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.
170 inline void
171 declare_no_pointers(char*, size_t) { }
172 
173 /// Unregister a range previously registered with declare_no_pointers.
174 inline void
175 undeclare_no_pointers(char*, size_t) { }
176 
177 /// The type of pointer safety supported by the implementation.
178 inline pointer_safety
179 get_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 */