libstdc++
atomic
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1 // -*- C++ -*- header.
2 
3 // Copyright (C) 2008-2022 Free Software Foundation, Inc.
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24 
25 /** @file include/atomic
26  * This is a Standard C++ Library header.
27  */
28 
29 // Based on "C++ Atomic Types and Operations" by Hans Boehm and Lawrence Crowl.
30 // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2427.html
31 
32 #ifndef _GLIBCXX_ATOMIC
33 #define _GLIBCXX_ATOMIC 1
34 
35 #pragma GCC system_header
36 
37 #if __cplusplus < 201103L
38 # include <bits/c++0x_warning.h>
39 #else
40 
41 #include <bits/atomic_base.h>
42 
43 namespace std _GLIBCXX_VISIBILITY(default)
44 {
45 _GLIBCXX_BEGIN_NAMESPACE_VERSION
46 
47  /**
48  * @addtogroup atomics
49  * @{
50  */
51 
52 #if __cplusplus >= 201703L
53 # define __cpp_lib_atomic_is_always_lock_free 201603L
54 #endif
55 
56  template<typename _Tp>
57  struct atomic;
58 
59  /// atomic<bool>
60  // NB: No operators or fetch-operations for this type.
61  template<>
62  struct atomic<bool>
63  {
64  using value_type = bool;
65 
66  private:
67  __atomic_base<bool> _M_base;
68 
69  public:
70  atomic() noexcept = default;
71  ~atomic() noexcept = default;
72  atomic(const atomic&) = delete;
73  atomic& operator=(const atomic&) = delete;
74  atomic& operator=(const atomic&) volatile = delete;
75 
76  constexpr atomic(bool __i) noexcept : _M_base(__i) { }
77 
78  bool
79  operator=(bool __i) noexcept
80  { return _M_base.operator=(__i); }
81 
82  bool
83  operator=(bool __i) volatile noexcept
84  { return _M_base.operator=(__i); }
85 
86  operator bool() const noexcept
87  { return _M_base.load(); }
88 
89  operator bool() const volatile noexcept
90  { return _M_base.load(); }
91 
92  bool
93  is_lock_free() const noexcept { return _M_base.is_lock_free(); }
94 
95  bool
96  is_lock_free() const volatile noexcept { return _M_base.is_lock_free(); }
97 
98 #if __cplusplus >= 201703L
99  static constexpr bool is_always_lock_free = ATOMIC_BOOL_LOCK_FREE == 2;
100 #endif
101 
102  void
103  store(bool __i, memory_order __m = memory_order_seq_cst) noexcept
104  { _M_base.store(__i, __m); }
105 
106  void
107  store(bool __i, memory_order __m = memory_order_seq_cst) volatile noexcept
108  { _M_base.store(__i, __m); }
109 
110  bool
111  load(memory_order __m = memory_order_seq_cst) const noexcept
112  { return _M_base.load(__m); }
113 
114  bool
115  load(memory_order __m = memory_order_seq_cst) const volatile noexcept
116  { return _M_base.load(__m); }
117 
118  bool
119  exchange(bool __i, memory_order __m = memory_order_seq_cst) noexcept
120  { return _M_base.exchange(__i, __m); }
121 
122  bool
123  exchange(bool __i,
124  memory_order __m = memory_order_seq_cst) volatile noexcept
125  { return _M_base.exchange(__i, __m); }
126 
127  bool
128  compare_exchange_weak(bool& __i1, bool __i2, memory_order __m1,
129  memory_order __m2) noexcept
130  { return _M_base.compare_exchange_weak(__i1, __i2, __m1, __m2); }
131 
132  bool
133  compare_exchange_weak(bool& __i1, bool __i2, memory_order __m1,
134  memory_order __m2) volatile noexcept
135  { return _M_base.compare_exchange_weak(__i1, __i2, __m1, __m2); }
136 
137  bool
138  compare_exchange_weak(bool& __i1, bool __i2,
139  memory_order __m = memory_order_seq_cst) noexcept
140  { return _M_base.compare_exchange_weak(__i1, __i2, __m); }
141 
142  bool
143  compare_exchange_weak(bool& __i1, bool __i2,
144  memory_order __m = memory_order_seq_cst) volatile noexcept
145  { return _M_base.compare_exchange_weak(__i1, __i2, __m); }
146 
147  bool
148  compare_exchange_strong(bool& __i1, bool __i2, memory_order __m1,
149  memory_order __m2) noexcept
150  { return _M_base.compare_exchange_strong(__i1, __i2, __m1, __m2); }
151 
152  bool
153  compare_exchange_strong(bool& __i1, bool __i2, memory_order __m1,
154  memory_order __m2) volatile noexcept
155  { return _M_base.compare_exchange_strong(__i1, __i2, __m1, __m2); }
156 
157  bool
158  compare_exchange_strong(bool& __i1, bool __i2,
159  memory_order __m = memory_order_seq_cst) noexcept
160  { return _M_base.compare_exchange_strong(__i1, __i2, __m); }
161 
162  bool
163  compare_exchange_strong(bool& __i1, bool __i2,
164  memory_order __m = memory_order_seq_cst) volatile noexcept
165  { return _M_base.compare_exchange_strong(__i1, __i2, __m); }
166 
167 #if __cpp_lib_atomic_wait
168  void
169  wait(bool __old, memory_order __m = memory_order_seq_cst) const noexcept
170  { _M_base.wait(__old, __m); }
171 
172  // TODO add const volatile overload
173 
174  void
175  notify_one() noexcept
176  { _M_base.notify_one(); }
177 
178  void
179  notify_all() noexcept
180  { _M_base.notify_all(); }
181 #endif // __cpp_lib_atomic_wait
182  };
183 
184 /// @cond undocumented
185 #if __cpp_lib_atomic_value_initialization
186 # define _GLIBCXX20_INIT(I) = I
187 #else
188 # define _GLIBCXX20_INIT(I)
189 #endif
190 /// @endcond
191 
192  /**
193  * @brief Generic atomic type, primary class template.
194  *
195  * @tparam _Tp Type to be made atomic, must be trivially copyable.
196  */
197  template<typename _Tp>
198  struct atomic
199  {
200  using value_type = _Tp;
201 
202  private:
203  // Align 1/2/4/8/16-byte types to at least their size.
204  static constexpr int _S_min_alignment
205  = (sizeof(_Tp) & (sizeof(_Tp) - 1)) || sizeof(_Tp) > 16
206  ? 0 : sizeof(_Tp);
207 
208  static constexpr int _S_alignment
209  = _S_min_alignment > alignof(_Tp) ? _S_min_alignment : alignof(_Tp);
210 
211  alignas(_S_alignment) _Tp _M_i _GLIBCXX20_INIT(_Tp());
212 
213  static_assert(__is_trivially_copyable(_Tp),
214  "std::atomic requires a trivially copyable type");
215 
216  static_assert(sizeof(_Tp) > 0,
217  "Incomplete or zero-sized types are not supported");
218 
219 #if __cplusplus > 201703L
220  static_assert(is_copy_constructible_v<_Tp>);
221  static_assert(is_move_constructible_v<_Tp>);
222  static_assert(is_copy_assignable_v<_Tp>);
223  static_assert(is_move_assignable_v<_Tp>);
224 #endif
225 
226  public:
227  atomic() = default;
228  ~atomic() noexcept = default;
229  atomic(const atomic&) = delete;
230  atomic& operator=(const atomic&) = delete;
231  atomic& operator=(const atomic&) volatile = delete;
232 
233  constexpr atomic(_Tp __i) noexcept : _M_i(__i) { }
234 
235  operator _Tp() const noexcept
236  { return load(); }
237 
238  operator _Tp() const volatile noexcept
239  { return load(); }
240 
241  _Tp
242  operator=(_Tp __i) noexcept
243  { store(__i); return __i; }
244 
245  _Tp
246  operator=(_Tp __i) volatile noexcept
247  { store(__i); return __i; }
248 
249  bool
250  is_lock_free() const noexcept
251  {
252  // Produce a fake, minimally aligned pointer.
253  return __atomic_is_lock_free(sizeof(_M_i),
254  reinterpret_cast<void *>(-_S_alignment));
255  }
256 
257  bool
258  is_lock_free() const volatile noexcept
259  {
260  // Produce a fake, minimally aligned pointer.
261  return __atomic_is_lock_free(sizeof(_M_i),
262  reinterpret_cast<void *>(-_S_alignment));
263  }
264 
265 #if __cplusplus >= 201703L
266  static constexpr bool is_always_lock_free
267  = __atomic_always_lock_free(sizeof(_M_i), 0);
268 #endif
269 
270  void
271  store(_Tp __i, memory_order __m = memory_order_seq_cst) noexcept
272  {
273  __atomic_store(std::__addressof(_M_i), std::__addressof(__i), int(__m));
274  }
275 
276  void
277  store(_Tp __i, memory_order __m = memory_order_seq_cst) volatile noexcept
278  {
279  __atomic_store(std::__addressof(_M_i), std::__addressof(__i), int(__m));
280  }
281 
282  _Tp
283  load(memory_order __m = memory_order_seq_cst) const noexcept
284  {
285  alignas(_Tp) unsigned char __buf[sizeof(_Tp)];
286  _Tp* __ptr = reinterpret_cast<_Tp*>(__buf);
287  __atomic_load(std::__addressof(_M_i), __ptr, int(__m));
288  return *__ptr;
289  }
290 
291  _Tp
292  load(memory_order __m = memory_order_seq_cst) const volatile noexcept
293  {
294  alignas(_Tp) unsigned char __buf[sizeof(_Tp)];
295  _Tp* __ptr = reinterpret_cast<_Tp*>(__buf);
296  __atomic_load(std::__addressof(_M_i), __ptr, int(__m));
297  return *__ptr;
298  }
299 
300  _Tp
301  exchange(_Tp __i, memory_order __m = memory_order_seq_cst) noexcept
302  {
303  alignas(_Tp) unsigned char __buf[sizeof(_Tp)];
304  _Tp* __ptr = reinterpret_cast<_Tp*>(__buf);
305  __atomic_exchange(std::__addressof(_M_i), std::__addressof(__i),
306  __ptr, int(__m));
307  return *__ptr;
308  }
309 
310  _Tp
311  exchange(_Tp __i,
312  memory_order __m = memory_order_seq_cst) volatile noexcept
313  {
314  alignas(_Tp) unsigned char __buf[sizeof(_Tp)];
315  _Tp* __ptr = reinterpret_cast<_Tp*>(__buf);
316  __atomic_exchange(std::__addressof(_M_i), std::__addressof(__i),
317  __ptr, int(__m));
318  return *__ptr;
319  }
320 
321  bool
322  compare_exchange_weak(_Tp& __e, _Tp __i, memory_order __s,
323  memory_order __f) noexcept
324  {
325  __glibcxx_assert(__is_valid_cmpexch_failure_order(__f));
326 
327  return __atomic_compare_exchange(std::__addressof(_M_i),
328  std::__addressof(__e),
329  std::__addressof(__i),
330  true, int(__s), int(__f));
331  }
332 
333  bool
334  compare_exchange_weak(_Tp& __e, _Tp __i, memory_order __s,
335  memory_order __f) volatile noexcept
336  {
337  __glibcxx_assert(__is_valid_cmpexch_failure_order(__f));
338 
339  return __atomic_compare_exchange(std::__addressof(_M_i),
340  std::__addressof(__e),
341  std::__addressof(__i),
342  true, int(__s), int(__f));
343  }
344 
345  bool
346  compare_exchange_weak(_Tp& __e, _Tp __i,
347  memory_order __m = memory_order_seq_cst) noexcept
348  { return compare_exchange_weak(__e, __i, __m,
349  __cmpexch_failure_order(__m)); }
350 
351  bool
352  compare_exchange_weak(_Tp& __e, _Tp __i,
353  memory_order __m = memory_order_seq_cst) volatile noexcept
354  { return compare_exchange_weak(__e, __i, __m,
355  __cmpexch_failure_order(__m)); }
356 
357  bool
358  compare_exchange_strong(_Tp& __e, _Tp __i, memory_order __s,
359  memory_order __f) noexcept
360  {
361  __glibcxx_assert(__is_valid_cmpexch_failure_order(__f));
362 
363  return __atomic_compare_exchange(std::__addressof(_M_i),
364  std::__addressof(__e),
365  std::__addressof(__i),
366  false, int(__s), int(__f));
367  }
368 
369  bool
370  compare_exchange_strong(_Tp& __e, _Tp __i, memory_order __s,
371  memory_order __f) volatile noexcept
372  {
373  __glibcxx_assert(__is_valid_cmpexch_failure_order(__f));
374 
375  return __atomic_compare_exchange(std::__addressof(_M_i),
376  std::__addressof(__e),
377  std::__addressof(__i),
378  false, int(__s), int(__f));
379  }
380 
381  bool
382  compare_exchange_strong(_Tp& __e, _Tp __i,
383  memory_order __m = memory_order_seq_cst) noexcept
384  { return compare_exchange_strong(__e, __i, __m,
385  __cmpexch_failure_order(__m)); }
386 
387  bool
388  compare_exchange_strong(_Tp& __e, _Tp __i,
389  memory_order __m = memory_order_seq_cst) volatile noexcept
390  { return compare_exchange_strong(__e, __i, __m,
391  __cmpexch_failure_order(__m)); }
392 
393 #if __cpp_lib_atomic_wait
394  void
395  wait(_Tp __old, memory_order __m = memory_order_seq_cst) const noexcept
396  {
397  std::__atomic_wait_address_v(&_M_i, __old,
398  [__m, this] { return this->load(__m); });
399  }
400 
401  // TODO add const volatile overload
402 
403  void
404  notify_one() noexcept
405  { std::__atomic_notify_address(&_M_i, false); }
406 
407  void
408  notify_all() noexcept
409  { std::__atomic_notify_address(&_M_i, true); }
410 #endif // __cpp_lib_atomic_wait
411 
412  };
413 #undef _GLIBCXX20_INIT
414 
415  /// Partial specialization for pointer types.
416  template<typename _Tp>
417  struct atomic<_Tp*>
418  {
419  using value_type = _Tp*;
420  using difference_type = ptrdiff_t;
421 
422  typedef _Tp* __pointer_type;
423  typedef __atomic_base<_Tp*> __base_type;
424  __base_type _M_b;
425 
426  atomic() noexcept = default;
427  ~atomic() noexcept = default;
428  atomic(const atomic&) = delete;
429  atomic& operator=(const atomic&) = delete;
430  atomic& operator=(const atomic&) volatile = delete;
431 
432  constexpr atomic(__pointer_type __p) noexcept : _M_b(__p) { }
433 
434  operator __pointer_type() const noexcept
435  { return __pointer_type(_M_b); }
436 
437  operator __pointer_type() const volatile noexcept
438  { return __pointer_type(_M_b); }
439 
440  __pointer_type
441  operator=(__pointer_type __p) noexcept
442  { return _M_b.operator=(__p); }
443 
444  __pointer_type
445  operator=(__pointer_type __p) volatile noexcept
446  { return _M_b.operator=(__p); }
447 
448  __pointer_type
449  operator++(int) noexcept
450  {
451 #if __cplusplus >= 201703L
452  static_assert( is_object<_Tp>::value, "pointer to object type" );
453 #endif
454  return _M_b++;
455  }
456 
457  __pointer_type
458  operator++(int) volatile noexcept
459  {
460 #if __cplusplus >= 201703L
461  static_assert( is_object<_Tp>::value, "pointer to object type" );
462 #endif
463  return _M_b++;
464  }
465 
466  __pointer_type
467  operator--(int) noexcept
468  {
469 #if __cplusplus >= 201703L
470  static_assert( is_object<_Tp>::value, "pointer to object type" );
471 #endif
472  return _M_b--;
473  }
474 
475  __pointer_type
476  operator--(int) volatile noexcept
477  {
478 #if __cplusplus >= 201703L
479  static_assert( is_object<_Tp>::value, "pointer to object type" );
480 #endif
481  return _M_b--;
482  }
483 
484  __pointer_type
485  operator++() noexcept
486  {
487 #if __cplusplus >= 201703L
488  static_assert( is_object<_Tp>::value, "pointer to object type" );
489 #endif
490  return ++_M_b;
491  }
492 
493  __pointer_type
494  operator++() volatile noexcept
495  {
496 #if __cplusplus >= 201703L
497  static_assert( is_object<_Tp>::value, "pointer to object type" );
498 #endif
499  return ++_M_b;
500  }
501 
502  __pointer_type
503  operator--() noexcept
504  {
505 #if __cplusplus >= 201703L
506  static_assert( is_object<_Tp>::value, "pointer to object type" );
507 #endif
508  return --_M_b;
509  }
510 
511  __pointer_type
512  operator--() volatile noexcept
513  {
514 #if __cplusplus >= 201703L
515  static_assert( is_object<_Tp>::value, "pointer to object type" );
516 #endif
517  return --_M_b;
518  }
519 
520  __pointer_type
521  operator+=(ptrdiff_t __d) noexcept
522  {
523 #if __cplusplus >= 201703L
524  static_assert( is_object<_Tp>::value, "pointer to object type" );
525 #endif
526  return _M_b.operator+=(__d);
527  }
528 
529  __pointer_type
530  operator+=(ptrdiff_t __d) volatile noexcept
531  {
532 #if __cplusplus >= 201703L
533  static_assert( is_object<_Tp>::value, "pointer to object type" );
534 #endif
535  return _M_b.operator+=(__d);
536  }
537 
538  __pointer_type
539  operator-=(ptrdiff_t __d) noexcept
540  {
541 #if __cplusplus >= 201703L
542  static_assert( is_object<_Tp>::value, "pointer to object type" );
543 #endif
544  return _M_b.operator-=(__d);
545  }
546 
547  __pointer_type
548  operator-=(ptrdiff_t __d) volatile noexcept
549  {
550 #if __cplusplus >= 201703L
551  static_assert( is_object<_Tp>::value, "pointer to object type" );
552 #endif
553  return _M_b.operator-=(__d);
554  }
555 
556  bool
557  is_lock_free() const noexcept
558  { return _M_b.is_lock_free(); }
559 
560  bool
561  is_lock_free() const volatile noexcept
562  { return _M_b.is_lock_free(); }
563 
564 #if __cplusplus >= 201703L
565  static constexpr bool is_always_lock_free
566  = ATOMIC_POINTER_LOCK_FREE == 2;
567 #endif
568 
569  void
570  store(__pointer_type __p,
571  memory_order __m = memory_order_seq_cst) noexcept
572  { return _M_b.store(__p, __m); }
573 
574  void
575  store(__pointer_type __p,
576  memory_order __m = memory_order_seq_cst) volatile noexcept
577  { return _M_b.store(__p, __m); }
578 
579  __pointer_type
580  load(memory_order __m = memory_order_seq_cst) const noexcept
581  { return _M_b.load(__m); }
582 
583  __pointer_type
584  load(memory_order __m = memory_order_seq_cst) const volatile noexcept
585  { return _M_b.load(__m); }
586 
587  __pointer_type
588  exchange(__pointer_type __p,
589  memory_order __m = memory_order_seq_cst) noexcept
590  { return _M_b.exchange(__p, __m); }
591 
592  __pointer_type
593  exchange(__pointer_type __p,
594  memory_order __m = memory_order_seq_cst) volatile noexcept
595  { return _M_b.exchange(__p, __m); }
596 
597  bool
598  compare_exchange_weak(__pointer_type& __p1, __pointer_type __p2,
599  memory_order __m1, memory_order __m2) noexcept
600  { return _M_b.compare_exchange_weak(__p1, __p2, __m1, __m2); }
601 
602  bool
603  compare_exchange_weak(__pointer_type& __p1, __pointer_type __p2,
604  memory_order __m1,
605  memory_order __m2) volatile noexcept
606  { return _M_b.compare_exchange_weak(__p1, __p2, __m1, __m2); }
607 
608  bool
609  compare_exchange_weak(__pointer_type& __p1, __pointer_type __p2,
610  memory_order __m = memory_order_seq_cst) noexcept
611  {
612  return compare_exchange_weak(__p1, __p2, __m,
613  __cmpexch_failure_order(__m));
614  }
615 
616  bool
617  compare_exchange_weak(__pointer_type& __p1, __pointer_type __p2,
618  memory_order __m = memory_order_seq_cst) volatile noexcept
619  {
620  return compare_exchange_weak(__p1, __p2, __m,
621  __cmpexch_failure_order(__m));
622  }
623 
624  bool
625  compare_exchange_strong(__pointer_type& __p1, __pointer_type __p2,
626  memory_order __m1, memory_order __m2) noexcept
627  { return _M_b.compare_exchange_strong(__p1, __p2, __m1, __m2); }
628 
629  bool
630  compare_exchange_strong(__pointer_type& __p1, __pointer_type __p2,
631  memory_order __m1,
632  memory_order __m2) volatile noexcept
633  { return _M_b.compare_exchange_strong(__p1, __p2, __m1, __m2); }
634 
635  bool
636  compare_exchange_strong(__pointer_type& __p1, __pointer_type __p2,
637  memory_order __m = memory_order_seq_cst) noexcept
638  {
639  return _M_b.compare_exchange_strong(__p1, __p2, __m,
640  __cmpexch_failure_order(__m));
641  }
642 
643  bool
644  compare_exchange_strong(__pointer_type& __p1, __pointer_type __p2,
645  memory_order __m = memory_order_seq_cst) volatile noexcept
646  {
647  return _M_b.compare_exchange_strong(__p1, __p2, __m,
648  __cmpexch_failure_order(__m));
649  }
650 
651 #if __cpp_lib_atomic_wait
652  void
653  wait(__pointer_type __old, memory_order __m = memory_order_seq_cst) const noexcept
654  { _M_b.wait(__old, __m); }
655 
656  // TODO add const volatile overload
657 
658  void
659  notify_one() noexcept
660  { _M_b.notify_one(); }
661 
662  void
663  notify_all() noexcept
664  { _M_b.notify_all(); }
665 #endif // __cpp_lib_atomic_wait
666 
667  __pointer_type
668  fetch_add(ptrdiff_t __d,
669  memory_order __m = memory_order_seq_cst) noexcept
670  {
671 #if __cplusplus >= 201703L
672  static_assert( is_object<_Tp>::value, "pointer to object type" );
673 #endif
674  return _M_b.fetch_add(__d, __m);
675  }
676 
677  __pointer_type
678  fetch_add(ptrdiff_t __d,
679  memory_order __m = memory_order_seq_cst) volatile noexcept
680  {
681 #if __cplusplus >= 201703L
682  static_assert( is_object<_Tp>::value, "pointer to object type" );
683 #endif
684  return _M_b.fetch_add(__d, __m);
685  }
686 
687  __pointer_type
688  fetch_sub(ptrdiff_t __d,
689  memory_order __m = memory_order_seq_cst) noexcept
690  {
691 #if __cplusplus >= 201703L
692  static_assert( is_object<_Tp>::value, "pointer to object type" );
693 #endif
694  return _M_b.fetch_sub(__d, __m);
695  }
696 
697  __pointer_type
698  fetch_sub(ptrdiff_t __d,
699  memory_order __m = memory_order_seq_cst) volatile noexcept
700  {
701 #if __cplusplus >= 201703L
702  static_assert( is_object<_Tp>::value, "pointer to object type" );
703 #endif
704  return _M_b.fetch_sub(__d, __m);
705  }
706  };
707 
708 
709  /// Explicit specialization for char.
710  template<>
711  struct atomic<char> : __atomic_base<char>
712  {
713  typedef char __integral_type;
714  typedef __atomic_base<char> __base_type;
715 
716  atomic() noexcept = default;
717  ~atomic() noexcept = default;
718  atomic(const atomic&) = delete;
719  atomic& operator=(const atomic&) = delete;
720  atomic& operator=(const atomic&) volatile = delete;
721 
722  constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
723 
724  using __base_type::operator __integral_type;
725  using __base_type::operator=;
726 
727 #if __cplusplus >= 201703L
728  static constexpr bool is_always_lock_free = ATOMIC_CHAR_LOCK_FREE == 2;
729 #endif
730  };
731 
732  /// Explicit specialization for signed char.
733  template<>
734  struct atomic<signed char> : __atomic_base<signed char>
735  {
736  typedef signed char __integral_type;
737  typedef __atomic_base<signed char> __base_type;
738 
739  atomic() noexcept= default;
740  ~atomic() noexcept = default;
741  atomic(const atomic&) = delete;
742  atomic& operator=(const atomic&) = delete;
743  atomic& operator=(const atomic&) volatile = delete;
744 
745  constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
746 
747  using __base_type::operator __integral_type;
748  using __base_type::operator=;
749 
750 #if __cplusplus >= 201703L
751  static constexpr bool is_always_lock_free = ATOMIC_CHAR_LOCK_FREE == 2;
752 #endif
753  };
754 
755  /// Explicit specialization for unsigned char.
756  template<>
757  struct atomic<unsigned char> : __atomic_base<unsigned char>
758  {
759  typedef unsigned char __integral_type;
760  typedef __atomic_base<unsigned char> __base_type;
761 
762  atomic() noexcept= default;
763  ~atomic() noexcept = default;
764  atomic(const atomic&) = delete;
765  atomic& operator=(const atomic&) = delete;
766  atomic& operator=(const atomic&) volatile = delete;
767 
768  constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
769 
770  using __base_type::operator __integral_type;
771  using __base_type::operator=;
772 
773 #if __cplusplus >= 201703L
774  static constexpr bool is_always_lock_free = ATOMIC_CHAR_LOCK_FREE == 2;
775 #endif
776  };
777 
778  /// Explicit specialization for short.
779  template<>
780  struct atomic<short> : __atomic_base<short>
781  {
782  typedef short __integral_type;
783  typedef __atomic_base<short> __base_type;
784 
785  atomic() noexcept = default;
786  ~atomic() noexcept = default;
787  atomic(const atomic&) = delete;
788  atomic& operator=(const atomic&) = delete;
789  atomic& operator=(const atomic&) volatile = delete;
790 
791  constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
792 
793  using __base_type::operator __integral_type;
794  using __base_type::operator=;
795 
796 #if __cplusplus >= 201703L
797  static constexpr bool is_always_lock_free = ATOMIC_SHORT_LOCK_FREE == 2;
798 #endif
799  };
800 
801  /// Explicit specialization for unsigned short.
802  template<>
803  struct atomic<unsigned short> : __atomic_base<unsigned short>
804  {
805  typedef unsigned short __integral_type;
806  typedef __atomic_base<unsigned short> __base_type;
807 
808  atomic() noexcept = default;
809  ~atomic() noexcept = default;
810  atomic(const atomic&) = delete;
811  atomic& operator=(const atomic&) = delete;
812  atomic& operator=(const atomic&) volatile = delete;
813 
814  constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
815 
816  using __base_type::operator __integral_type;
817  using __base_type::operator=;
818 
819 #if __cplusplus >= 201703L
820  static constexpr bool is_always_lock_free = ATOMIC_SHORT_LOCK_FREE == 2;
821 #endif
822  };
823 
824  /// Explicit specialization for int.
825  template<>
826  struct atomic<int> : __atomic_base<int>
827  {
828  typedef int __integral_type;
829  typedef __atomic_base<int> __base_type;
830 
831  atomic() noexcept = default;
832  ~atomic() noexcept = default;
833  atomic(const atomic&) = delete;
834  atomic& operator=(const atomic&) = delete;
835  atomic& operator=(const atomic&) volatile = delete;
836 
837  constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
838 
839  using __base_type::operator __integral_type;
840  using __base_type::operator=;
841 
842 #if __cplusplus >= 201703L
843  static constexpr bool is_always_lock_free = ATOMIC_INT_LOCK_FREE == 2;
844 #endif
845  };
846 
847  /// Explicit specialization for unsigned int.
848  template<>
849  struct atomic<unsigned int> : __atomic_base<unsigned int>
850  {
851  typedef unsigned int __integral_type;
852  typedef __atomic_base<unsigned int> __base_type;
853 
854  atomic() noexcept = default;
855  ~atomic() noexcept = default;
856  atomic(const atomic&) = delete;
857  atomic& operator=(const atomic&) = delete;
858  atomic& operator=(const atomic&) volatile = delete;
859 
860  constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
861 
862  using __base_type::operator __integral_type;
863  using __base_type::operator=;
864 
865 #if __cplusplus >= 201703L
866  static constexpr bool is_always_lock_free = ATOMIC_INT_LOCK_FREE == 2;
867 #endif
868  };
869 
870  /// Explicit specialization for long.
871  template<>
872  struct atomic<long> : __atomic_base<long>
873  {
874  typedef long __integral_type;
875  typedef __atomic_base<long> __base_type;
876 
877  atomic() noexcept = default;
878  ~atomic() noexcept = default;
879  atomic(const atomic&) = delete;
880  atomic& operator=(const atomic&) = delete;
881  atomic& operator=(const atomic&) volatile = delete;
882 
883  constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
884 
885  using __base_type::operator __integral_type;
886  using __base_type::operator=;
887 
888 #if __cplusplus >= 201703L
889  static constexpr bool is_always_lock_free = ATOMIC_LONG_LOCK_FREE == 2;
890 #endif
891  };
892 
893  /// Explicit specialization for unsigned long.
894  template<>
895  struct atomic<unsigned long> : __atomic_base<unsigned long>
896  {
897  typedef unsigned long __integral_type;
898  typedef __atomic_base<unsigned long> __base_type;
899 
900  atomic() noexcept = default;
901  ~atomic() noexcept = default;
902  atomic(const atomic&) = delete;
903  atomic& operator=(const atomic&) = delete;
904  atomic& operator=(const atomic&) volatile = delete;
905 
906  constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
907 
908  using __base_type::operator __integral_type;
909  using __base_type::operator=;
910 
911 #if __cplusplus >= 201703L
912  static constexpr bool is_always_lock_free = ATOMIC_LONG_LOCK_FREE == 2;
913 #endif
914  };
915 
916  /// Explicit specialization for long long.
917  template<>
918  struct atomic<long long> : __atomic_base<long long>
919  {
920  typedef long long __integral_type;
921  typedef __atomic_base<long long> __base_type;
922 
923  atomic() noexcept = default;
924  ~atomic() noexcept = default;
925  atomic(const atomic&) = delete;
926  atomic& operator=(const atomic&) = delete;
927  atomic& operator=(const atomic&) volatile = delete;
928 
929  constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
930 
931  using __base_type::operator __integral_type;
932  using __base_type::operator=;
933 
934 #if __cplusplus >= 201703L
935  static constexpr bool is_always_lock_free = ATOMIC_LLONG_LOCK_FREE == 2;
936 #endif
937  };
938 
939  /// Explicit specialization for unsigned long long.
940  template<>
941  struct atomic<unsigned long long> : __atomic_base<unsigned long long>
942  {
943  typedef unsigned long long __integral_type;
944  typedef __atomic_base<unsigned long long> __base_type;
945 
946  atomic() noexcept = default;
947  ~atomic() noexcept = default;
948  atomic(const atomic&) = delete;
949  atomic& operator=(const atomic&) = delete;
950  atomic& operator=(const atomic&) volatile = delete;
951 
952  constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
953 
954  using __base_type::operator __integral_type;
955  using __base_type::operator=;
956 
957 #if __cplusplus >= 201703L
958  static constexpr bool is_always_lock_free = ATOMIC_LLONG_LOCK_FREE == 2;
959 #endif
960  };
961 
962  /// Explicit specialization for wchar_t.
963  template<>
964  struct atomic<wchar_t> : __atomic_base<wchar_t>
965  {
966  typedef wchar_t __integral_type;
967  typedef __atomic_base<wchar_t> __base_type;
968 
969  atomic() noexcept = default;
970  ~atomic() noexcept = default;
971  atomic(const atomic&) = delete;
972  atomic& operator=(const atomic&) = delete;
973  atomic& operator=(const atomic&) volatile = delete;
974 
975  constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
976 
977  using __base_type::operator __integral_type;
978  using __base_type::operator=;
979 
980 #if __cplusplus >= 201703L
981  static constexpr bool is_always_lock_free = ATOMIC_WCHAR_T_LOCK_FREE == 2;
982 #endif
983  };
984 
985 #ifdef _GLIBCXX_USE_CHAR8_T
986  /// Explicit specialization for char8_t.
987  template<>
988  struct atomic<char8_t> : __atomic_base<char8_t>
989  {
990  typedef char8_t __integral_type;
991  typedef __atomic_base<char8_t> __base_type;
992 
993  atomic() noexcept = default;
994  ~atomic() noexcept = default;
995  atomic(const atomic&) = delete;
996  atomic& operator=(const atomic&) = delete;
997  atomic& operator=(const atomic&) volatile = delete;
998 
999  constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
1000 
1001  using __base_type::operator __integral_type;
1002  using __base_type::operator=;
1003 
1004 #if __cplusplus > 201402L
1005  static constexpr bool is_always_lock_free
1006  = ATOMIC_CHAR8_T_LOCK_FREE == 2;
1007 #endif
1008  };
1009 #endif
1010 
1011  /// Explicit specialization for char16_t.
1012  template<>
1013  struct atomic<char16_t> : __atomic_base<char16_t>
1014  {
1015  typedef char16_t __integral_type;
1016  typedef __atomic_base<char16_t> __base_type;
1017 
1018  atomic() noexcept = default;
1019  ~atomic() noexcept = default;
1020  atomic(const atomic&) = delete;
1021  atomic& operator=(const atomic&) = delete;
1022  atomic& operator=(const atomic&) volatile = delete;
1023 
1024  constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
1025 
1026  using __base_type::operator __integral_type;
1027  using __base_type::operator=;
1028 
1029 #if __cplusplus >= 201703L
1030  static constexpr bool is_always_lock_free
1031  = ATOMIC_CHAR16_T_LOCK_FREE == 2;
1032 #endif
1033  };
1034 
1035  /// Explicit specialization for char32_t.
1036  template<>
1037  struct atomic<char32_t> : __atomic_base<char32_t>
1038  {
1039  typedef char32_t __integral_type;
1040  typedef __atomic_base<char32_t> __base_type;
1041 
1042  atomic() noexcept = default;
1043  ~atomic() noexcept = default;
1044  atomic(const atomic&) = delete;
1045  atomic& operator=(const atomic&) = delete;
1046  atomic& operator=(const atomic&) volatile = delete;
1047 
1048  constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
1049 
1050  using __base_type::operator __integral_type;
1051  using __base_type::operator=;
1052 
1053 #if __cplusplus >= 201703L
1054  static constexpr bool is_always_lock_free
1055  = ATOMIC_CHAR32_T_LOCK_FREE == 2;
1056 #endif
1057  };
1058 
1059 
1060  /// atomic_bool
1061  typedef atomic<bool> atomic_bool;
1062 
1063  /// atomic_char
1064  typedef atomic<char> atomic_char;
1065 
1066  /// atomic_schar
1067  typedef atomic<signed char> atomic_schar;
1068 
1069  /// atomic_uchar
1070  typedef atomic<unsigned char> atomic_uchar;
1071 
1072  /// atomic_short
1073  typedef atomic<short> atomic_short;
1074 
1075  /// atomic_ushort
1076  typedef atomic<unsigned short> atomic_ushort;
1077 
1078  /// atomic_int
1079  typedef atomic<int> atomic_int;
1080 
1081  /// atomic_uint
1082  typedef atomic<unsigned int> atomic_uint;
1083 
1084  /// atomic_long
1085  typedef atomic<long> atomic_long;
1086 
1087  /// atomic_ulong
1088  typedef atomic<unsigned long> atomic_ulong;
1089 
1090  /// atomic_llong
1091  typedef atomic<long long> atomic_llong;
1092 
1093  /// atomic_ullong
1094  typedef atomic<unsigned long long> atomic_ullong;
1095 
1096  /// atomic_wchar_t
1097  typedef atomic<wchar_t> atomic_wchar_t;
1098 
1099 #ifdef _GLIBCXX_USE_CHAR8_T
1100  /// atomic_char8_t
1101  typedef atomic<char8_t> atomic_char8_t;
1102 #endif
1103 
1104  /// atomic_char16_t
1105  typedef atomic<char16_t> atomic_char16_t;
1106 
1107  /// atomic_char32_t
1108  typedef atomic<char32_t> atomic_char32_t;
1109 
1110 #ifdef _GLIBCXX_USE_C99_STDINT_TR1
1111  // _GLIBCXX_RESOLVE_LIB_DEFECTS
1112  // 2441. Exact-width atomic typedefs should be provided
1113 
1114  /// atomic_int8_t
1115  typedef atomic<int8_t> atomic_int8_t;
1116 
1117  /// atomic_uint8_t
1118  typedef atomic<uint8_t> atomic_uint8_t;
1119 
1120  /// atomic_int16_t
1121  typedef atomic<int16_t> atomic_int16_t;
1122 
1123  /// atomic_uint16_t
1124  typedef atomic<uint16_t> atomic_uint16_t;
1125 
1126  /// atomic_int32_t
1127  typedef atomic<int32_t> atomic_int32_t;
1128 
1129  /// atomic_uint32_t
1130  typedef atomic<uint32_t> atomic_uint32_t;
1131 
1132  /// atomic_int64_t
1133  typedef atomic<int64_t> atomic_int64_t;
1134 
1135  /// atomic_uint64_t
1136  typedef atomic<uint64_t> atomic_uint64_t;
1137 
1138 
1139  /// atomic_int_least8_t
1140  typedef atomic<int_least8_t> atomic_int_least8_t;
1141 
1142  /// atomic_uint_least8_t
1143  typedef atomic<uint_least8_t> atomic_uint_least8_t;
1144 
1145  /// atomic_int_least16_t
1146  typedef atomic<int_least16_t> atomic_int_least16_t;
1147 
1148  /// atomic_uint_least16_t
1149  typedef atomic<uint_least16_t> atomic_uint_least16_t;
1150 
1151  /// atomic_int_least32_t
1152  typedef atomic<int_least32_t> atomic_int_least32_t;
1153 
1154  /// atomic_uint_least32_t
1155  typedef atomic<uint_least32_t> atomic_uint_least32_t;
1156 
1157  /// atomic_int_least64_t
1158  typedef atomic<int_least64_t> atomic_int_least64_t;
1159 
1160  /// atomic_uint_least64_t
1161  typedef atomic<uint_least64_t> atomic_uint_least64_t;
1162 
1163 
1164  /// atomic_int_fast8_t
1165  typedef atomic<int_fast8_t> atomic_int_fast8_t;
1166 
1167  /// atomic_uint_fast8_t
1168  typedef atomic<uint_fast8_t> atomic_uint_fast8_t;
1169 
1170  /// atomic_int_fast16_t
1171  typedef atomic<int_fast16_t> atomic_int_fast16_t;
1172 
1173  /// atomic_uint_fast16_t
1174  typedef atomic<uint_fast16_t> atomic_uint_fast16_t;
1175 
1176  /// atomic_int_fast32_t
1177  typedef atomic<int_fast32_t> atomic_int_fast32_t;
1178 
1179  /// atomic_uint_fast32_t
1180  typedef atomic<uint_fast32_t> atomic_uint_fast32_t;
1181 
1182  /// atomic_int_fast64_t
1183  typedef atomic<int_fast64_t> atomic_int_fast64_t;
1184 
1185  /// atomic_uint_fast64_t
1186  typedef atomic<uint_fast64_t> atomic_uint_fast64_t;
1187 #endif
1188 
1189 
1190  /// atomic_intptr_t
1191  typedef atomic<intptr_t> atomic_intptr_t;
1192 
1193  /// atomic_uintptr_t
1194  typedef atomic<uintptr_t> atomic_uintptr_t;
1195 
1196  /// atomic_size_t
1197  typedef atomic<size_t> atomic_size_t;
1198 
1199  /// atomic_ptrdiff_t
1200  typedef atomic<ptrdiff_t> atomic_ptrdiff_t;
1201 
1202 #ifdef _GLIBCXX_USE_C99_STDINT_TR1
1203  /// atomic_intmax_t
1204  typedef atomic<intmax_t> atomic_intmax_t;
1205 
1206  /// atomic_uintmax_t
1207  typedef atomic<uintmax_t> atomic_uintmax_t;
1208 #endif
1209 
1210  // Function definitions, atomic_flag operations.
1211  inline bool
1212  atomic_flag_test_and_set_explicit(atomic_flag* __a,
1213  memory_order __m) noexcept
1214  { return __a->test_and_set(__m); }
1215 
1216  inline bool
1217  atomic_flag_test_and_set_explicit(volatile atomic_flag* __a,
1218  memory_order __m) noexcept
1219  { return __a->test_and_set(__m); }
1220 
1221 #if __cpp_lib_atomic_flag_test
1222  inline bool
1223  atomic_flag_test(const atomic_flag* __a) noexcept
1224  { return __a->test(); }
1225 
1226  inline bool
1227  atomic_flag_test(const volatile atomic_flag* __a) noexcept
1228  { return __a->test(); }
1229 
1230  inline bool
1231  atomic_flag_test_explicit(const atomic_flag* __a,
1232  memory_order __m) noexcept
1233  { return __a->test(__m); }
1234 
1235  inline bool
1236  atomic_flag_test_explicit(const volatile atomic_flag* __a,
1237  memory_order __m) noexcept
1238  { return __a->test(__m); }
1239 #endif
1240 
1241  inline void
1242  atomic_flag_clear_explicit(atomic_flag* __a, memory_order __m) noexcept
1243  { __a->clear(__m); }
1244 
1245  inline void
1246  atomic_flag_clear_explicit(volatile atomic_flag* __a,
1247  memory_order __m) noexcept
1248  { __a->clear(__m); }
1249 
1250  inline bool
1251  atomic_flag_test_and_set(atomic_flag* __a) noexcept
1252  { return atomic_flag_test_and_set_explicit(__a, memory_order_seq_cst); }
1253 
1254  inline bool
1255  atomic_flag_test_and_set(volatile atomic_flag* __a) noexcept
1256  { return atomic_flag_test_and_set_explicit(__a, memory_order_seq_cst); }
1257 
1258  inline void
1259  atomic_flag_clear(atomic_flag* __a) noexcept
1260  { atomic_flag_clear_explicit(__a, memory_order_seq_cst); }
1261 
1262  inline void
1263  atomic_flag_clear(volatile atomic_flag* __a) noexcept
1264  { atomic_flag_clear_explicit(__a, memory_order_seq_cst); }
1265 
1266 #if __cpp_lib_atomic_wait
1267  inline void
1268  atomic_flag_wait(atomic_flag* __a, bool __old) noexcept
1269  { __a->wait(__old); }
1270 
1271  inline void
1272  atomic_flag_wait_explicit(atomic_flag* __a, bool __old,
1273  memory_order __m) noexcept
1274  { __a->wait(__old, __m); }
1275 
1276  inline void
1277  atomic_flag_notify_one(atomic_flag* __a) noexcept
1278  { __a->notify_one(); }
1279 
1280  inline void
1281  atomic_flag_notify_all(atomic_flag* __a) noexcept
1282  { __a->notify_all(); }
1283 #endif // __cpp_lib_atomic_wait
1284 
1285  /// @cond undocumented
1286  // _GLIBCXX_RESOLVE_LIB_DEFECTS
1287  // 3220. P0558 broke conforming C++14 uses of atomic shared_ptr
1288  template<typename _Tp>
1289  using __atomic_val_t = __type_identity_t<_Tp>;
1290  template<typename _Tp>
1291  using __atomic_diff_t = typename atomic<_Tp>::difference_type;
1292  /// @endcond
1293 
1294  // [atomics.nonmembers] Non-member functions.
1295  // Function templates generally applicable to atomic types.
1296  template<typename _ITp>
1297  inline bool
1298  atomic_is_lock_free(const atomic<_ITp>* __a) noexcept
1299  { return __a->is_lock_free(); }
1300 
1301  template<typename _ITp>
1302  inline bool
1303  atomic_is_lock_free(const volatile atomic<_ITp>* __a) noexcept
1304  { return __a->is_lock_free(); }
1305 
1306  template<typename _ITp>
1307  inline void
1308  atomic_init(atomic<_ITp>* __a, __atomic_val_t<_ITp> __i) noexcept
1309  { __a->store(__i, memory_order_relaxed); }
1310 
1311  template<typename _ITp>
1312  inline void
1313  atomic_init(volatile atomic<_ITp>* __a, __atomic_val_t<_ITp> __i) noexcept
1314  { __a->store(__i, memory_order_relaxed); }
1315 
1316  template<typename _ITp>
1317  inline void
1318  atomic_store_explicit(atomic<_ITp>* __a, __atomic_val_t<_ITp> __i,
1319  memory_order __m) noexcept
1320  { __a->store(__i, __m); }
1321 
1322  template<typename _ITp>
1323  inline void
1324  atomic_store_explicit(volatile atomic<_ITp>* __a, __atomic_val_t<_ITp> __i,
1325  memory_order __m) noexcept
1326  { __a->store(__i, __m); }
1327 
1328  template<typename _ITp>
1329  inline _ITp
1330  atomic_load_explicit(const atomic<_ITp>* __a, memory_order __m) noexcept
1331  { return __a->load(__m); }
1332 
1333  template<typename _ITp>
1334  inline _ITp
1335  atomic_load_explicit(const volatile atomic<_ITp>* __a,
1336  memory_order __m) noexcept
1337  { return __a->load(__m); }
1338 
1339  template<typename _ITp>
1340  inline _ITp
1341  atomic_exchange_explicit(atomic<_ITp>* __a, __atomic_val_t<_ITp> __i,
1342  memory_order __m) noexcept
1343  { return __a->exchange(__i, __m); }
1344 
1345  template<typename _ITp>
1346  inline _ITp
1347  atomic_exchange_explicit(volatile atomic<_ITp>* __a,
1348  __atomic_val_t<_ITp> __i,
1349  memory_order __m) noexcept
1350  { return __a->exchange(__i, __m); }
1351 
1352  template<typename _ITp>
1353  inline bool
1354  atomic_compare_exchange_weak_explicit(atomic<_ITp>* __a,
1355  __atomic_val_t<_ITp>* __i1,
1356  __atomic_val_t<_ITp> __i2,
1357  memory_order __m1,
1358  memory_order __m2) noexcept
1359  { return __a->compare_exchange_weak(*__i1, __i2, __m1, __m2); }
1360 
1361  template<typename _ITp>
1362  inline bool
1363  atomic_compare_exchange_weak_explicit(volatile atomic<_ITp>* __a,
1364  __atomic_val_t<_ITp>* __i1,
1365  __atomic_val_t<_ITp> __i2,
1366  memory_order __m1,
1367  memory_order __m2) noexcept
1368  { return __a->compare_exchange_weak(*__i1, __i2, __m1, __m2); }
1369 
1370  template<typename _ITp>
1371  inline bool
1372  atomic_compare_exchange_strong_explicit(atomic<_ITp>* __a,
1373  __atomic_val_t<_ITp>* __i1,
1374  __atomic_val_t<_ITp> __i2,
1375  memory_order __m1,
1376  memory_order __m2) noexcept
1377  { return __a->compare_exchange_strong(*__i1, __i2, __m1, __m2); }
1378 
1379  template<typename _ITp>
1380  inline bool
1381  atomic_compare_exchange_strong_explicit(volatile atomic<_ITp>* __a,
1382  __atomic_val_t<_ITp>* __i1,
1383  __atomic_val_t<_ITp> __i2,
1384  memory_order __m1,
1385  memory_order __m2) noexcept
1386  { return __a->compare_exchange_strong(*__i1, __i2, __m1, __m2); }
1387 
1388 
1389  template<typename _ITp>
1390  inline void
1391  atomic_store(atomic<_ITp>* __a, __atomic_val_t<_ITp> __i) noexcept
1392  { atomic_store_explicit(__a, __i, memory_order_seq_cst); }
1393 
1394  template<typename _ITp>
1395  inline void
1396  atomic_store(volatile atomic<_ITp>* __a, __atomic_val_t<_ITp> __i) noexcept
1397  { atomic_store_explicit(__a, __i, memory_order_seq_cst); }
1398 
1399  template<typename _ITp>
1400  inline _ITp
1401  atomic_load(const atomic<_ITp>* __a) noexcept
1402  { return atomic_load_explicit(__a, memory_order_seq_cst); }
1403 
1404  template<typename _ITp>
1405  inline _ITp
1406  atomic_load(const volatile atomic<_ITp>* __a) noexcept
1407  { return atomic_load_explicit(__a, memory_order_seq_cst); }
1408 
1409  template<typename _ITp>
1410  inline _ITp
1411  atomic_exchange(atomic<_ITp>* __a, __atomic_val_t<_ITp> __i) noexcept
1412  { return atomic_exchange_explicit(__a, __i, memory_order_seq_cst); }
1413 
1414  template<typename _ITp>
1415  inline _ITp
1416  atomic_exchange(volatile atomic<_ITp>* __a,
1417  __atomic_val_t<_ITp> __i) noexcept
1418  { return atomic_exchange_explicit(__a, __i, memory_order_seq_cst); }
1419 
1420  template<typename _ITp>
1421  inline bool
1422  atomic_compare_exchange_weak(atomic<_ITp>* __a,
1423  __atomic_val_t<_ITp>* __i1,
1424  __atomic_val_t<_ITp> __i2) noexcept
1425  {
1426  return atomic_compare_exchange_weak_explicit(__a, __i1, __i2,
1427  memory_order_seq_cst,
1428  memory_order_seq_cst);
1429  }
1430 
1431  template<typename _ITp>
1432  inline bool
1433  atomic_compare_exchange_weak(volatile atomic<_ITp>* __a,
1434  __atomic_val_t<_ITp>* __i1,
1435  __atomic_val_t<_ITp> __i2) noexcept
1436  {
1437  return atomic_compare_exchange_weak_explicit(__a, __i1, __i2,
1438  memory_order_seq_cst,
1439  memory_order_seq_cst);
1440  }
1441 
1442  template<typename _ITp>
1443  inline bool
1444  atomic_compare_exchange_strong(atomic<_ITp>* __a,
1445  __atomic_val_t<_ITp>* __i1,
1446  __atomic_val_t<_ITp> __i2) noexcept
1447  {
1448  return atomic_compare_exchange_strong_explicit(__a, __i1, __i2,
1449  memory_order_seq_cst,
1450  memory_order_seq_cst);
1451  }
1452 
1453  template<typename _ITp>
1454  inline bool
1455  atomic_compare_exchange_strong(volatile atomic<_ITp>* __a,
1456  __atomic_val_t<_ITp>* __i1,
1457  __atomic_val_t<_ITp> __i2) noexcept
1458  {
1459  return atomic_compare_exchange_strong_explicit(__a, __i1, __i2,
1460  memory_order_seq_cst,
1461  memory_order_seq_cst);
1462  }
1463 
1464 
1465 #if __cpp_lib_atomic_wait
1466  template<typename _Tp>
1467  inline void
1468  atomic_wait(const atomic<_Tp>* __a,
1469  typename std::atomic<_Tp>::value_type __old) noexcept
1470  { __a->wait(__old); }
1471 
1472  template<typename _Tp>
1473  inline void
1474  atomic_wait_explicit(const atomic<_Tp>* __a,
1475  typename std::atomic<_Tp>::value_type __old,
1476  std::memory_order __m) noexcept
1477  { __a->wait(__old, __m); }
1478 
1479  template<typename _Tp>
1480  inline void
1481  atomic_notify_one(atomic<_Tp>* __a) noexcept
1482  { __a->notify_one(); }
1483 
1484  template<typename _Tp>
1485  inline void
1486  atomic_notify_all(atomic<_Tp>* __a) noexcept
1487  { __a->notify_all(); }
1488 #endif // __cpp_lib_atomic_wait
1489 
1490  // Function templates for atomic_integral and atomic_pointer operations only.
1491  // Some operations (and, or, xor) are only available for atomic integrals,
1492  // which is implemented by taking a parameter of type __atomic_base<_ITp>*.
1493 
1494  template<typename _ITp>
1495  inline _ITp
1496  atomic_fetch_add_explicit(atomic<_ITp>* __a,
1497  __atomic_diff_t<_ITp> __i,
1498  memory_order __m) noexcept
1499  { return __a->fetch_add(__i, __m); }
1500 
1501  template<typename _ITp>
1502  inline _ITp
1503  atomic_fetch_add_explicit(volatile atomic<_ITp>* __a,
1504  __atomic_diff_t<_ITp> __i,
1505  memory_order __m) noexcept
1506  { return __a->fetch_add(__i, __m); }
1507 
1508  template<typename _ITp>
1509  inline _ITp
1510  atomic_fetch_sub_explicit(atomic<_ITp>* __a,
1511  __atomic_diff_t<_ITp> __i,
1512  memory_order __m) noexcept
1513  { return __a->fetch_sub(__i, __m); }
1514 
1515  template<typename _ITp>
1516  inline _ITp
1517  atomic_fetch_sub_explicit(volatile atomic<_ITp>* __a,
1518  __atomic_diff_t<_ITp> __i,
1519  memory_order __m) noexcept
1520  { return __a->fetch_sub(__i, __m); }
1521 
1522  template<typename _ITp>
1523  inline _ITp
1524  atomic_fetch_and_explicit(__atomic_base<_ITp>* __a,
1525  __atomic_val_t<_ITp> __i,
1526  memory_order __m) noexcept
1527  { return __a->fetch_and(__i, __m); }
1528 
1529  template<typename _ITp>
1530  inline _ITp
1531  atomic_fetch_and_explicit(volatile __atomic_base<_ITp>* __a,
1532  __atomic_val_t<_ITp> __i,
1533  memory_order __m) noexcept
1534  { return __a->fetch_and(__i, __m); }
1535 
1536  template<typename _ITp>
1537  inline _ITp
1538  atomic_fetch_or_explicit(__atomic_base<_ITp>* __a,
1539  __atomic_val_t<_ITp> __i,
1540  memory_order __m) noexcept
1541  { return __a->fetch_or(__i, __m); }
1542 
1543  template<typename _ITp>
1544  inline _ITp
1545  atomic_fetch_or_explicit(volatile __atomic_base<_ITp>* __a,
1546  __atomic_val_t<_ITp> __i,
1547  memory_order __m) noexcept
1548  { return __a->fetch_or(__i, __m); }
1549 
1550  template<typename _ITp>
1551  inline _ITp
1552  atomic_fetch_xor_explicit(__atomic_base<_ITp>* __a,
1553  __atomic_val_t<_ITp> __i,
1554  memory_order __m) noexcept
1555  { return __a->fetch_xor(__i, __m); }
1556 
1557  template<typename _ITp>
1558  inline _ITp
1559  atomic_fetch_xor_explicit(volatile __atomic_base<_ITp>* __a,
1560  __atomic_val_t<_ITp> __i,
1561  memory_order __m) noexcept
1562  { return __a->fetch_xor(__i, __m); }
1563 
1564  template<typename _ITp>
1565  inline _ITp
1566  atomic_fetch_add(atomic<_ITp>* __a,
1567  __atomic_diff_t<_ITp> __i) noexcept
1568  { return atomic_fetch_add_explicit(__a, __i, memory_order_seq_cst); }
1569 
1570  template<typename _ITp>
1571  inline _ITp
1572  atomic_fetch_add(volatile atomic<_ITp>* __a,
1573  __atomic_diff_t<_ITp> __i) noexcept
1574  { return atomic_fetch_add_explicit(__a, __i, memory_order_seq_cst); }
1575 
1576  template<typename _ITp>
1577  inline _ITp
1578  atomic_fetch_sub(atomic<_ITp>* __a,
1579  __atomic_diff_t<_ITp> __i) noexcept
1580  { return atomic_fetch_sub_explicit(__a, __i, memory_order_seq_cst); }
1581 
1582  template<typename _ITp>
1583  inline _ITp
1584  atomic_fetch_sub(volatile atomic<_ITp>* __a,
1585  __atomic_diff_t<_ITp> __i) noexcept
1586  { return atomic_fetch_sub_explicit(__a, __i, memory_order_seq_cst); }
1587 
1588  template<typename _ITp>
1589  inline _ITp
1590  atomic_fetch_and(__atomic_base<_ITp>* __a,
1591  __atomic_val_t<_ITp> __i) noexcept
1592  { return atomic_fetch_and_explicit(__a, __i, memory_order_seq_cst); }
1593 
1594  template<typename _ITp>
1595  inline _ITp
1596  atomic_fetch_and(volatile __atomic_base<_ITp>* __a,
1597  __atomic_val_t<_ITp> __i) noexcept
1598  { return atomic_fetch_and_explicit(__a, __i, memory_order_seq_cst); }
1599 
1600  template<typename _ITp>
1601  inline _ITp
1602  atomic_fetch_or(__atomic_base<_ITp>* __a,
1603  __atomic_val_t<_ITp> __i) noexcept
1604  { return atomic_fetch_or_explicit(__a, __i, memory_order_seq_cst); }
1605 
1606  template<typename _ITp>
1607  inline _ITp
1608  atomic_fetch_or(volatile __atomic_base<_ITp>* __a,
1609  __atomic_val_t<_ITp> __i) noexcept
1610  { return atomic_fetch_or_explicit(__a, __i, memory_order_seq_cst); }
1611 
1612  template<typename _ITp>
1613  inline _ITp
1614  atomic_fetch_xor(__atomic_base<_ITp>* __a,
1615  __atomic_val_t<_ITp> __i) noexcept
1616  { return atomic_fetch_xor_explicit(__a, __i, memory_order_seq_cst); }
1617 
1618  template<typename _ITp>
1619  inline _ITp
1620  atomic_fetch_xor(volatile __atomic_base<_ITp>* __a,
1621  __atomic_val_t<_ITp> __i) noexcept
1622  { return atomic_fetch_xor_explicit(__a, __i, memory_order_seq_cst); }
1623 
1624 #if __cplusplus > 201703L
1625 #define __cpp_lib_atomic_float 201711L
1626  template<>
1627  struct atomic<float> : __atomic_float<float>
1628  {
1629  atomic() noexcept = default;
1630 
1631  constexpr
1632  atomic(float __fp) noexcept : __atomic_float<float>(__fp)
1633  { }
1634 
1635  atomic& operator=(const atomic&) volatile = delete;
1636  atomic& operator=(const atomic&) = delete;
1637 
1638  using __atomic_float<float>::operator=;
1639  };
1640 
1641  template<>
1642  struct atomic<double> : __atomic_float<double>
1643  {
1644  atomic() noexcept = default;
1645 
1646  constexpr
1647  atomic(double __fp) noexcept : __atomic_float<double>(__fp)
1648  { }
1649 
1650  atomic& operator=(const atomic&) volatile = delete;
1651  atomic& operator=(const atomic&) = delete;
1652 
1653  using __atomic_float<double>::operator=;
1654  };
1655 
1656  template<>
1657  struct atomic<long double> : __atomic_float<long double>
1658  {
1659  atomic() noexcept = default;
1660 
1661  constexpr
1662  atomic(long double __fp) noexcept : __atomic_float<long double>(__fp)
1663  { }
1664 
1665  atomic& operator=(const atomic&) volatile = delete;
1666  atomic& operator=(const atomic&) = delete;
1667 
1668  using __atomic_float<long double>::operator=;
1669  };
1670 
1671 #define __cpp_lib_atomic_ref 201806L
1672 
1673  /// Class template to provide atomic operations on a non-atomic variable.
1674  template<typename _Tp>
1675  struct atomic_ref : __atomic_ref<_Tp>
1676  {
1677  explicit
1678  atomic_ref(_Tp& __t) noexcept : __atomic_ref<_Tp>(__t)
1679  { }
1680 
1681  atomic_ref& operator=(const atomic_ref&) = delete;
1682 
1683  atomic_ref(const atomic_ref&) = default;
1684 
1685  using __atomic_ref<_Tp>::operator=;
1686  };
1687 
1688 #endif // C++2a
1689 
1690  /// @} group atomics
1691 
1692 _GLIBCXX_END_NAMESPACE_VERSION
1693 } // namespace
1694 
1695 #endif // C++11
1696 
1697 #endif // _GLIBCXX_ATOMIC