libstdc++
memory
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1 // <memory> -*- C++ -*-
2 
3 // Copyright (C) 2001-2019 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  */
42 
43 #ifndef _GLIBCXX_MEMORY
44 #define _GLIBCXX_MEMORY 1
45 
46 #pragma GCC system_header
47 
48 /**
49  * @defgroup memory Memory
50  * @ingroup utilities
51  *
52  * Components for memory allocation, deallocation, and management.
53  */
54 
55 /**
56  * @defgroup pointer_abstractions Pointer Abstractions
57  * @ingroup memory
58  *
59  * Smart pointers, etc.
60  */
61 
62 #include <bits/stl_algobase.h>
63 #include <bits/allocator.h>
64 #include <bits/stl_construct.h>
65 #include <bits/stl_uninitialized.h>
66 #include <bits/stl_tempbuf.h>
67 #include <bits/stl_raw_storage_iter.h>
68 
69 #if __cplusplus >= 201103L
70 # include <exception> // std::exception
71 # include <typeinfo> // std::type_info in get_deleter
72 # include <iosfwd> // std::basic_ostream
73 # include <ext/atomicity.h>
74 # include <ext/concurrence.h>
75 # include <bits/functexcept.h>
76 # include <bits/stl_function.h> // std::less
77 # include <bits/uses_allocator.h>
78 # include <type_traits>
79 # include <debug/debug.h>
80 # include <bits/unique_ptr.h>
81 # include <bits/shared_ptr.h>
82 # include <bits/shared_ptr_atomic.h>
83 # if _GLIBCXX_USE_DEPRECATED
84 # include <backward/auto_ptr.h>
85 # endif
86 #else
87 # include <backward/auto_ptr.h>
88 #endif
89 
90 #if __cplusplus >= 201103L
91 #include <cstdint>
92 #if __cplusplus > 201703L
93 # include <bit> // for ispow2
94 # include <new> // for placement operator new
95 # include <tuple> // for tuple, make_tuple, make_from_tuple
96 #endif
97 namespace std _GLIBCXX_VISIBILITY(default)
98 {
99 _GLIBCXX_BEGIN_NAMESPACE_VERSION
100 
101 /**
102  * @brief Fit aligned storage in buffer.
103  *
104  * [ptr.align]
105  *
106  * This function tries to fit @a __size bytes of storage with alignment
107  * @a __align into the buffer @a __ptr of size @a __space bytes. If such
108  * a buffer fits then @a __ptr is changed to point to the first byte of the
109  * aligned storage and @a __space is reduced by the bytes used for alignment.
110  *
111  * @param __align A fundamental or extended alignment value.
112  * @param __size Size of the aligned storage required.
113  * @param __ptr Pointer to a buffer of @a __space bytes.
114  * @param __space Size of the buffer pointed to by @a __ptr.
115  * @return the updated pointer if the aligned storage fits, otherwise nullptr.
116  */
117 inline void*
118 align(size_t __align, size_t __size, void*& __ptr, size_t& __space) noexcept
119 {
120 #ifdef _GLIBCXX_USE_C99_STDINT_TR1
121  const auto __intptr = reinterpret_cast<uintptr_t>(__ptr);
122 #else
123  // Cannot use std::uintptr_t so assume that std::size_t can be used instead.
124  static_assert(sizeof(size_t) >= sizeof(void*),
125  "std::size_t must be a suitable substitute for std::uintptr_t");
126  const auto __intptr = reinterpret_cast<unsigned long long>(__ptr);
127 #endif
128  const auto __aligned = (__intptr - 1u + __align) & -__align;
129  const auto __diff = __aligned - __intptr;
130  if ((__size + __diff) > __space)
131  return nullptr;
132  else
133  {
134  __space -= __diff;
135  return __ptr = reinterpret_cast<void*>(__aligned);
136  }
137 }
138 
139 // 20.7.4 [util.dynamic.safety], pointer safety
140 
141 enum class pointer_safety { relaxed, preferred, strict };
142 
143 inline void
144 declare_reachable(void*) { }
145 
146 template <typename _Tp>
147  inline _Tp*
148  undeclare_reachable(_Tp* __p) { return __p; }
149 
150 inline void
151 declare_no_pointers(char*, size_t) { }
152 
153 inline void
154 undeclare_no_pointers(char*, size_t) { }
155 
156 inline pointer_safety
157 get_pointer_safety() noexcept { return pointer_safety::relaxed; }
158 
159 #if __cplusplus > 201703L
160 #define __cpp_lib_assume_aligned 201811L
161  /** @brief Inform the compiler that a pointer is aligned.
162  *
163  * @tparam _Align An alignment value (i.e. a power of two)
164  * @tparam _Tp An object type
165  * @param __ptr A pointer that is aligned to _Align
166  *
167  * C++20 20.10.6 [ptr.align]
168  *
169  * @ingroup memory
170  */
171  template<size_t _Align, class _Tp>
172  [[nodiscard,__gnu__::__always_inline__]]
173  constexpr _Tp*
174  assume_aligned(_Tp* __ptr) noexcept
175  {
176  static_assert(std::ispow2(_Align));
177  if (std::is_constant_evaluated())
178  return __ptr;
179  else
180  {
181  // This function is expected to be used in hot code, where
182  // __glibcxx_assert would add unwanted overhead.
183  _GLIBCXX_DEBUG_ASSERT((std::uintptr_t)__ptr % _Align == 0);
184  return static_cast<_Tp*>(__builtin_assume_aligned(__ptr, _Align));
185  }
186  }
187 #endif // C++2a
188 
189 #if __cplusplus > 201703L
190  template<typename _Tp>
191  struct __is_pair : false_type { };
192  template<typename _Tp, typename _Up>
193  struct __is_pair<pair<_Tp, _Up>> : true_type { };
194  template<typename _Tp, typename _Up>
195  struct __is_pair<const pair<_Tp, _Up>> : true_type { };
196 
197  template<typename _Tp, typename __ = _Require<__not_<__is_pair<_Tp>>>,
198  typename _Alloc, typename... _Args>
199  constexpr auto
200  __uses_alloc_args(const _Alloc& __a, _Args&&... __args) noexcept
201  {
202  if constexpr (uses_allocator_v<remove_cv_t<_Tp>, _Alloc>)
203  {
204  if constexpr (is_constructible_v<_Tp, allocator_arg_t,
205  const _Alloc&, _Args...>)
206  {
207  return tuple<allocator_arg_t, const _Alloc&, _Args&&...>(
208  allocator_arg, __a, std::forward<_Args>(__args)...);
209  }
210  else
211  {
212  static_assert(is_constructible_v<_Tp, _Args..., const _Alloc&>,
213  "construction with an allocator must be possible"
214  " if uses_allocator is true");
215 
216  return tuple<_Args&&..., const _Alloc&>(
217  std::forward<_Args>(__args)..., __a);
218  }
219  }
220  else
221  {
222  static_assert(is_constructible_v<_Tp, _Args...>);
223 
224  return tuple<_Args&&...>(std::forward<_Args>(__args)...);
225  }
226  }
227 
228 #if __cpp_concepts
229  template<typename _Tp>
230  concept _Std_pair = __is_pair<_Tp>::value;
231 #endif
232 
233 // This is a temporary workaround until -fconcepts is implied by -std=gnu++2a
234 #if __cpp_concepts
235 # define _GLIBCXX_STD_PAIR_CONSTRAINT(T) _Std_pair T
236 # define _GLIBCXX_STD_PAIR_CONSTRAINT_(T) _Std_pair T
237 #else
238 # define _GLIBCXX_STD_PAIR_CONSTRAINT(T) \
239  typename T, typename __ = _Require<__is_pair<T>>
240 # define _GLIBCXX_STD_PAIR_CONSTRAINT_(T) typename T, typename
241 #endif
242 
243  template<typename _Tp,
244 #if ! __cpp_concepts
245  typename __ = _Require<__not_<__is_pair<_Tp>>>,
246 #endif
247  typename _Alloc, typename... _Args>
248  constexpr auto
249  uses_allocator_construction_args(const _Alloc& __a,
250  _Args&&... __args) noexcept
251 #if __cpp_concepts
252  requires (! _Std_pair<_Tp>)
253 #endif
254  {
255  return std::__uses_alloc_args<_Tp>(__a, std::forward<_Args>(__args)...);
256  }
257 
258  template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
259  typename _Tuple1, typename _Tuple2>
260  constexpr auto
261  uses_allocator_construction_args(const _Alloc& __a, piecewise_construct_t,
262  _Tuple1&& __x, _Tuple2&& __y) noexcept;
263 
264  template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc>
265  constexpr auto
266  uses_allocator_construction_args(const _Alloc&) noexcept;
267 
268  template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
269  typename _Up, typename _Vp>
270  constexpr auto
271  uses_allocator_construction_args(const _Alloc&, _Up&&, _Vp&&) noexcept;
272 
273  template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
274  typename _Up, typename _Vp>
275  constexpr auto
276  uses_allocator_construction_args(const _Alloc&,
277  const pair<_Up, _Vp>&) noexcept;
278 
279  template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
280  typename _Up, typename _Vp>
281  constexpr auto
282  uses_allocator_construction_args(const _Alloc&, pair<_Up, _Vp>&&) noexcept;
283 
284  template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
285  typename _Tuple1, typename _Tuple2>
286  constexpr auto
287  uses_allocator_construction_args(const _Alloc& __a, piecewise_construct_t,
288  _Tuple1&& __x, _Tuple2&& __y) noexcept
289  {
290  using _Tp1 = typename _Tp::first_type;
291  using _Tp2 = typename _Tp::second_type;
292 
293  return std::make_tuple(piecewise_construct,
294  std::apply([&__a](auto&&... __args1) {
295  return std::uses_allocator_construction_args<_Tp1>(
296  __a, std::forward<decltype(__args1)>(__args1)...);
297  }, std::forward<_Tuple1>(__x)),
298  std::apply([&__a](auto&&... __args2) {
299  return std::uses_allocator_construction_args<_Tp2>(
300  __a, std::forward<decltype(__args2)>(__args2)...);
301  }, std::forward<_Tuple2>(__y)));
302  }
303 
304  template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc>
305  constexpr auto
306  uses_allocator_construction_args(const _Alloc& __a) noexcept
307  {
308  using _Tp1 = typename _Tp::first_type;
309  using _Tp2 = typename _Tp::second_type;
310 
311  return std::make_tuple(piecewise_construct,
312  std::uses_allocator_construction_args<_Tp1>(__a),
313  std::uses_allocator_construction_args<_Tp2>(__a));
314  }
315 
316  template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
317  typename _Up, typename _Vp>
318  constexpr auto
319  uses_allocator_construction_args(const _Alloc& __a, _Up&& __u, _Vp&& __v)
320  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::forward<_Up>(__u)),
328  std::uses_allocator_construction_args<_Tp2>(__a,
329  std::forward<_Vp>(__v)));
330  }
331 
332  template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
333  typename _Up, typename _Vp>
334  constexpr auto
335  uses_allocator_construction_args(const _Alloc& __a,
336  const pair<_Up, _Vp>& __pr) noexcept
337  {
338  using _Tp1 = typename _Tp::first_type;
339  using _Tp2 = typename _Tp::second_type;
340 
341  return std::make_tuple(piecewise_construct,
342  std::uses_allocator_construction_args<_Tp1>(__a, __pr.first),
343  std::uses_allocator_construction_args<_Tp2>(__a, __pr.second));
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  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,
357  std::move(__pr).first),
358  std::uses_allocator_construction_args<_Tp2>(__a,
359  std::move(__pr).second));
360  }
361 
362  template<typename _Tp, typename _Alloc, typename... _Args>
363  inline _Tp
364  make_obj_using_allocator(const _Alloc& __a, _Args&&... __args)
365  {
366  return std::make_from_tuple<_Tp>(
367  std::uses_allocator_construction_args<_Tp>(__a,
368  std::forward<_Args>(__args)...));
369  }
370 
371  template<typename _Tp, typename _Alloc, typename... _Args>
372  inline _Tp*
373  uninitialized_construct_using_allocator(_Tp* __p, const _Alloc& __a,
374  _Args&&... __args)
375  {
376  void* __vp = const_cast<void*>(static_cast<const volatile void*>(__p));
377  return ::new(__vp) _Tp(std::make_obj_using_allocator<_Tp>(__a,
378  std::forward<_Args>(__args)...));
379  }
380 
381 #endif // C++2a
382 
383 _GLIBCXX_END_NAMESPACE_VERSION
384 } // namespace
385 #endif // C++11
386 
387 #if __cplusplus > 201402L
388 // Parallel STL algorithms
389 # if __PSTL_EXECUTION_POLICIES_DEFINED
390 // If <execution> has already been included, pull in implementations
391 # include <pstl/glue_memory_impl.h>
392 # else
393 // Otherwise just pull in forward declarations
394 # include <pstl/glue_memory_defs.h>
395 # endif
396 
397 // Feature test macro for parallel algorithms
398 # define __cpp_lib_parallel_algorithm 201603L
399 #endif // C++17
400 
401 #endif /* _GLIBCXX_MEMORY */