1// -*- C++ -*- header.
2
3// Copyright (C) 2008-2021 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/** @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
43namespace 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 201603
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() const noexcept
176    { _M_base.notify_one(); }
177
178    void
179    notify_all() const noexcept
180    { _M_base.notify_all(); }
181#endif // __cpp_lib_atomic_wait
182  };
183
184#if __cplusplus <= 201703L
185# define _GLIBCXX20_INIT(I)
186#else
187# define _GLIBCXX20_INIT(I) = I
188#endif
189
190  /**
191   *  @brief Generic atomic type, primary class template.
192   *
193   *  @tparam _Tp  Type to be made atomic, must be trivially copyable.
194   */
195  template<typename _Tp>
196    struct atomic
197    {
198      using value_type = _Tp;
199
200    private:
201      // Align 1/2/4/8/16-byte types to at least their size.
202      static constexpr int _S_min_alignment
203	= (sizeof(_Tp) & (sizeof(_Tp) - 1)) || sizeof(_Tp) > 16
204	? 0 : sizeof(_Tp);
205
206      static constexpr int _S_alignment
207        = _S_min_alignment > alignof(_Tp) ? _S_min_alignment : alignof(_Tp);
208
209      alignas(_S_alignment) _Tp _M_i _GLIBCXX20_INIT(_Tp());
210
211      static_assert(__is_trivially_copyable(_Tp),
212		    "std::atomic requires a trivially copyable type");
213
214      static_assert(sizeof(_Tp) > 0,
215		    "Incomplete or zero-sized types are not supported");
216
217#if __cplusplus > 201703L
218      static_assert(is_copy_constructible_v<_Tp>);
219      static_assert(is_move_constructible_v<_Tp>);
220      static_assert(is_copy_assignable_v<_Tp>);
221      static_assert(is_move_assignable_v<_Tp>);
222#endif
223
224    public:
225      atomic() = default;
226      ~atomic() noexcept = default;
227      atomic(const atomic&) = delete;
228      atomic& operator=(const atomic&) = delete;
229      atomic& operator=(const atomic&) volatile = delete;
230
231      constexpr atomic(_Tp __i) noexcept : _M_i(__i) { }
232
233      operator _Tp() const noexcept
234      { return load(); }
235
236      operator _Tp() const volatile noexcept
237      { return load(); }
238
239      _Tp
240      operator=(_Tp __i) noexcept
241      { store(__i); return __i; }
242
243      _Tp
244      operator=(_Tp __i) volatile noexcept
245      { store(__i); return __i; }
246
247      bool
248      is_lock_free() const noexcept
249      {
250	// Produce a fake, minimally aligned pointer.
251	return __atomic_is_lock_free(sizeof(_M_i),
252	    reinterpret_cast<void *>(-_S_alignment));
253      }
254
255      bool
256      is_lock_free() const volatile noexcept
257      {
258	// Produce a fake, minimally aligned pointer.
259	return __atomic_is_lock_free(sizeof(_M_i),
260	    reinterpret_cast<void *>(-_S_alignment));
261      }
262
263#if __cplusplus >= 201703L
264      static constexpr bool is_always_lock_free
265	= __atomic_always_lock_free(sizeof(_M_i), 0);
266#endif
267
268      void
269      store(_Tp __i, memory_order __m = memory_order_seq_cst) noexcept
270      {
271	__atomic_store(std::__addressof(_M_i), std::__addressof(__i), int(__m));
272      }
273
274      void
275      store(_Tp __i, memory_order __m = memory_order_seq_cst) volatile noexcept
276      {
277	__atomic_store(std::__addressof(_M_i), std::__addressof(__i), int(__m));
278      }
279
280      _Tp
281      load(memory_order __m = memory_order_seq_cst) const noexcept
282      {
283	alignas(_Tp) unsigned char __buf[sizeof(_Tp)];
284	_Tp* __ptr = reinterpret_cast<_Tp*>(__buf);
285	__atomic_load(std::__addressof(_M_i), __ptr, int(__m));
286	return *__ptr;
287      }
288
289      _Tp
290      load(memory_order __m = memory_order_seq_cst) const volatile noexcept
291      {
292        alignas(_Tp) unsigned char __buf[sizeof(_Tp)];
293	_Tp* __ptr = reinterpret_cast<_Tp*>(__buf);
294	__atomic_load(std::__addressof(_M_i), __ptr, int(__m));
295	return *__ptr;
296      }
297
298      _Tp
299      exchange(_Tp __i, memory_order __m = memory_order_seq_cst) noexcept
300      {
301        alignas(_Tp) unsigned char __buf[sizeof(_Tp)];
302	_Tp* __ptr = reinterpret_cast<_Tp*>(__buf);
303	__atomic_exchange(std::__addressof(_M_i), std::__addressof(__i),
304			  __ptr, int(__m));
305	return *__ptr;
306      }
307
308      _Tp
309      exchange(_Tp __i,
310	       memory_order __m = memory_order_seq_cst) volatile noexcept
311      {
312        alignas(_Tp) unsigned char __buf[sizeof(_Tp)];
313	_Tp* __ptr = reinterpret_cast<_Tp*>(__buf);
314	__atomic_exchange(std::__addressof(_M_i), std::__addressof(__i),
315			  __ptr, int(__m));
316	return *__ptr;
317      }
318
319      bool
320      compare_exchange_weak(_Tp& __e, _Tp __i, memory_order __s,
321			    memory_order __f) noexcept
322      {
323	return __atomic_compare_exchange(std::__addressof(_M_i),
324					 std::__addressof(__e),
325					 std::__addressof(__i),
326					 true, int(__s), int(__f));
327      }
328
329      bool
330      compare_exchange_weak(_Tp& __e, _Tp __i, memory_order __s,
331			    memory_order __f) volatile noexcept
332      {
333	return __atomic_compare_exchange(std::__addressof(_M_i),
334					 std::__addressof(__e),
335					 std::__addressof(__i),
336					 true, int(__s), int(__f));
337      }
338
339      bool
340      compare_exchange_weak(_Tp& __e, _Tp __i,
341			    memory_order __m = memory_order_seq_cst) noexcept
342      { return compare_exchange_weak(__e, __i, __m,
343                                     __cmpexch_failure_order(__m)); }
344
345      bool
346      compare_exchange_weak(_Tp& __e, _Tp __i,
347		     memory_order __m = memory_order_seq_cst) volatile noexcept
348      { return compare_exchange_weak(__e, __i, __m,
349                                     __cmpexch_failure_order(__m)); }
350
351      bool
352      compare_exchange_strong(_Tp& __e, _Tp __i, memory_order __s,
353			      memory_order __f) noexcept
354      {
355	return __atomic_compare_exchange(std::__addressof(_M_i),
356					 std::__addressof(__e),
357					 std::__addressof(__i),
358					 false, int(__s), int(__f));
359      }
360
361      bool
362      compare_exchange_strong(_Tp& __e, _Tp __i, memory_order __s,
363			      memory_order __f) volatile noexcept
364      {
365	return __atomic_compare_exchange(std::__addressof(_M_i),
366					 std::__addressof(__e),
367					 std::__addressof(__i),
368					 false, int(__s), int(__f));
369      }
370
371      bool
372      compare_exchange_strong(_Tp& __e, _Tp __i,
373			       memory_order __m = memory_order_seq_cst) noexcept
374      { return compare_exchange_strong(__e, __i, __m,
375                                       __cmpexch_failure_order(__m)); }
376
377      bool
378      compare_exchange_strong(_Tp& __e, _Tp __i,
379		     memory_order __m = memory_order_seq_cst) volatile noexcept
380      { return compare_exchange_strong(__e, __i, __m,
381                                       __cmpexch_failure_order(__m)); }
382
383#if __cpp_lib_atomic_wait
384    void
385    wait(_Tp __old, memory_order __m = memory_order_seq_cst) const noexcept
386    {
387      std::__atomic_wait_address_v(&_M_i, __old,
388			 [__m, this] { return this->load(__m); });
389    }
390
391    // TODO add const volatile overload
392
393    void
394    notify_one() const noexcept
395    { std::__atomic_notify_address(&_M_i, false); }
396
397    void
398    notify_all() const noexcept
399    { std::__atomic_notify_address(&_M_i, true); }
400#endif // __cpp_lib_atomic_wait
401
402    };
403#undef _GLIBCXX20_INIT
404
405  /// Partial specialization for pointer types.
406  template<typename _Tp>
407    struct atomic<_Tp*>
408    {
409      using value_type = _Tp*;
410      using difference_type = ptrdiff_t;
411
412      typedef _Tp* 			__pointer_type;
413      typedef __atomic_base<_Tp*>	__base_type;
414      __base_type			_M_b;
415
416      atomic() noexcept = default;
417      ~atomic() noexcept = default;
418      atomic(const atomic&) = delete;
419      atomic& operator=(const atomic&) = delete;
420      atomic& operator=(const atomic&) volatile = delete;
421
422      constexpr atomic(__pointer_type __p) noexcept : _M_b(__p) { }
423
424      operator __pointer_type() const noexcept
425      { return __pointer_type(_M_b); }
426
427      operator __pointer_type() const volatile noexcept
428      { return __pointer_type(_M_b); }
429
430      __pointer_type
431      operator=(__pointer_type __p) noexcept
432      { return _M_b.operator=(__p); }
433
434      __pointer_type
435      operator=(__pointer_type __p) volatile noexcept
436      { return _M_b.operator=(__p); }
437
438      __pointer_type
439      operator++(int) noexcept
440      {
441#if __cplusplus >= 201703L
442	static_assert( is_object<_Tp>::value, "pointer to object type" );
443#endif
444	return _M_b++;
445      }
446
447      __pointer_type
448      operator++(int) volatile noexcept
449      {
450#if __cplusplus >= 201703L
451	static_assert( is_object<_Tp>::value, "pointer to object type" );
452#endif
453	return _M_b++;
454      }
455
456      __pointer_type
457      operator--(int) noexcept
458      {
459#if __cplusplus >= 201703L
460	static_assert( is_object<_Tp>::value, "pointer to object type" );
461#endif
462	return _M_b--;
463      }
464
465      __pointer_type
466      operator--(int) volatile noexcept
467      {
468#if __cplusplus >= 201703L
469	static_assert( is_object<_Tp>::value, "pointer to object type" );
470#endif
471	return _M_b--;
472      }
473
474      __pointer_type
475      operator++() noexcept
476      {
477#if __cplusplus >= 201703L
478	static_assert( is_object<_Tp>::value, "pointer to object type" );
479#endif
480	return ++_M_b;
481      }
482
483      __pointer_type
484      operator++() volatile noexcept
485      {
486#if __cplusplus >= 201703L
487	static_assert( is_object<_Tp>::value, "pointer to object type" );
488#endif
489	return ++_M_b;
490      }
491
492      __pointer_type
493      operator--() noexcept
494      {
495#if __cplusplus >= 201703L
496	static_assert( is_object<_Tp>::value, "pointer to object type" );
497#endif
498	return --_M_b;
499      }
500
501      __pointer_type
502      operator--() volatile noexcept
503      {
504#if __cplusplus >= 201703L
505	static_assert( is_object<_Tp>::value, "pointer to object type" );
506#endif
507	return --_M_b;
508      }
509
510      __pointer_type
511      operator+=(ptrdiff_t __d) noexcept
512      {
513#if __cplusplus >= 201703L
514	static_assert( is_object<_Tp>::value, "pointer to object type" );
515#endif
516	return _M_b.operator+=(__d);
517      }
518
519      __pointer_type
520      operator+=(ptrdiff_t __d) volatile noexcept
521      {
522#if __cplusplus >= 201703L
523	static_assert( is_object<_Tp>::value, "pointer to object type" );
524#endif
525	return _M_b.operator+=(__d);
526      }
527
528      __pointer_type
529      operator-=(ptrdiff_t __d) noexcept
530      {
531#if __cplusplus >= 201703L
532	static_assert( is_object<_Tp>::value, "pointer to object type" );
533#endif
534	return _M_b.operator-=(__d);
535      }
536
537      __pointer_type
538      operator-=(ptrdiff_t __d) volatile noexcept
539      {
540#if __cplusplus >= 201703L
541	static_assert( is_object<_Tp>::value, "pointer to object type" );
542#endif
543	return _M_b.operator-=(__d);
544      }
545
546      bool
547      is_lock_free() const noexcept
548      { return _M_b.is_lock_free(); }
549
550      bool
551      is_lock_free() const volatile noexcept
552      { return _M_b.is_lock_free(); }
553
554#if __cplusplus >= 201703L
555    static constexpr bool is_always_lock_free = ATOMIC_POINTER_LOCK_FREE == 2;
556#endif
557
558      void
559      store(__pointer_type __p,
560	    memory_order __m = memory_order_seq_cst) noexcept
561      { return _M_b.store(__p, __m); }
562
563      void
564      store(__pointer_type __p,
565	    memory_order __m = memory_order_seq_cst) volatile noexcept
566      { return _M_b.store(__p, __m); }
567
568      __pointer_type
569      load(memory_order __m = memory_order_seq_cst) const noexcept
570      { return _M_b.load(__m); }
571
572      __pointer_type
573      load(memory_order __m = memory_order_seq_cst) const volatile noexcept
574      { return _M_b.load(__m); }
575
576      __pointer_type
577      exchange(__pointer_type __p,
578	       memory_order __m = memory_order_seq_cst) noexcept
579      { return _M_b.exchange(__p, __m); }
580
581      __pointer_type
582      exchange(__pointer_type __p,
583	       memory_order __m = memory_order_seq_cst) volatile noexcept
584      { return _M_b.exchange(__p, __m); }
585
586      bool
587      compare_exchange_weak(__pointer_type& __p1, __pointer_type __p2,
588			    memory_order __m1, memory_order __m2) noexcept
589      { return _M_b.compare_exchange_strong(__p1, __p2, __m1, __m2); }
590
591      bool
592      compare_exchange_weak(__pointer_type& __p1, __pointer_type __p2,
593			    memory_order __m1,
594			    memory_order __m2) volatile noexcept
595      { return _M_b.compare_exchange_strong(__p1, __p2, __m1, __m2); }
596
597      bool
598      compare_exchange_weak(__pointer_type& __p1, __pointer_type __p2,
599			    memory_order __m = memory_order_seq_cst) noexcept
600      {
601	return compare_exchange_weak(__p1, __p2, __m,
602				     __cmpexch_failure_order(__m));
603      }
604
605      bool
606      compare_exchange_weak(__pointer_type& __p1, __pointer_type __p2,
607		    memory_order __m = memory_order_seq_cst) volatile noexcept
608      {
609	return compare_exchange_weak(__p1, __p2, __m,
610				     __cmpexch_failure_order(__m));
611      }
612
613      bool
614      compare_exchange_strong(__pointer_type& __p1, __pointer_type __p2,
615			      memory_order __m1, memory_order __m2) noexcept
616      { return _M_b.compare_exchange_strong(__p1, __p2, __m1, __m2); }
617
618      bool
619      compare_exchange_strong(__pointer_type& __p1, __pointer_type __p2,
620			      memory_order __m1,
621			      memory_order __m2) volatile noexcept
622      { return _M_b.compare_exchange_strong(__p1, __p2, __m1, __m2); }
623
624      bool
625      compare_exchange_strong(__pointer_type& __p1, __pointer_type __p2,
626			      memory_order __m = memory_order_seq_cst) noexcept
627      {
628	return _M_b.compare_exchange_strong(__p1, __p2, __m,
629					    __cmpexch_failure_order(__m));
630      }
631
632      bool
633      compare_exchange_strong(__pointer_type& __p1, __pointer_type __p2,
634		    memory_order __m = memory_order_seq_cst) volatile noexcept
635      {
636	return _M_b.compare_exchange_strong(__p1, __p2, __m,
637					    __cmpexch_failure_order(__m));
638      }
639
640#if __cpp_lib_atomic_wait
641    void
642    wait(__pointer_type __old, memory_order __m = memory_order_seq_cst) noexcept
643    { _M_b.wait(__old, __m); }
644
645    // TODO add const volatile overload
646
647    void
648    notify_one() const noexcept
649    { _M_b.notify_one(); }
650
651    void
652    notify_all() const noexcept
653    { _M_b.notify_all(); }
654#endif // __cpp_lib_atomic_wait
655      __pointer_type
656      fetch_add(ptrdiff_t __d,
657		memory_order __m = memory_order_seq_cst) noexcept
658      {
659#if __cplusplus >= 201703L
660	static_assert( is_object<_Tp>::value, "pointer to object type" );
661#endif
662	return _M_b.fetch_add(__d, __m);
663      }
664
665      __pointer_type
666      fetch_add(ptrdiff_t __d,
667		memory_order __m = memory_order_seq_cst) volatile noexcept
668      {
669#if __cplusplus >= 201703L
670	static_assert( is_object<_Tp>::value, "pointer to object type" );
671#endif
672	return _M_b.fetch_add(__d, __m);
673      }
674
675      __pointer_type
676      fetch_sub(ptrdiff_t __d,
677		memory_order __m = memory_order_seq_cst) noexcept
678      {
679#if __cplusplus >= 201703L
680	static_assert( is_object<_Tp>::value, "pointer to object type" );
681#endif
682	return _M_b.fetch_sub(__d, __m);
683      }
684
685      __pointer_type
686      fetch_sub(ptrdiff_t __d,
687		memory_order __m = memory_order_seq_cst) volatile noexcept
688      {
689#if __cplusplus >= 201703L
690	static_assert( is_object<_Tp>::value, "pointer to object type" );
691#endif
692	return _M_b.fetch_sub(__d, __m);
693      }
694    };
695
696
697  /// Explicit specialization for char.
698  template<>
699    struct atomic<char> : __atomic_base<char>
700    {
701      typedef char 			__integral_type;
702      typedef __atomic_base<char> 	__base_type;
703
704      atomic() noexcept = default;
705      ~atomic() noexcept = default;
706      atomic(const atomic&) = delete;
707      atomic& operator=(const atomic&) = delete;
708      atomic& operator=(const atomic&) volatile = delete;
709
710      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
711
712      using __base_type::operator __integral_type;
713      using __base_type::operator=;
714
715#if __cplusplus >= 201703L
716    static constexpr bool is_always_lock_free = ATOMIC_CHAR_LOCK_FREE == 2;
717#endif
718    };
719
720  /// Explicit specialization for signed char.
721  template<>
722    struct atomic<signed char> : __atomic_base<signed char>
723    {
724      typedef signed char 		__integral_type;
725      typedef __atomic_base<signed char> 	__base_type;
726
727      atomic() noexcept= default;
728      ~atomic() noexcept = default;
729      atomic(const atomic&) = delete;
730      atomic& operator=(const atomic&) = delete;
731      atomic& operator=(const atomic&) volatile = delete;
732
733      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
734
735      using __base_type::operator __integral_type;
736      using __base_type::operator=;
737
738#if __cplusplus >= 201703L
739    static constexpr bool is_always_lock_free = ATOMIC_CHAR_LOCK_FREE == 2;
740#endif
741    };
742
743  /// Explicit specialization for unsigned char.
744  template<>
745    struct atomic<unsigned char> : __atomic_base<unsigned char>
746    {
747      typedef unsigned char 		__integral_type;
748      typedef __atomic_base<unsigned char> 	__base_type;
749
750      atomic() noexcept= default;
751      ~atomic() noexcept = default;
752      atomic(const atomic&) = delete;
753      atomic& operator=(const atomic&) = delete;
754      atomic& operator=(const atomic&) volatile = delete;
755
756      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
757
758      using __base_type::operator __integral_type;
759      using __base_type::operator=;
760
761#if __cplusplus >= 201703L
762    static constexpr bool is_always_lock_free = ATOMIC_CHAR_LOCK_FREE == 2;
763#endif
764    };
765
766  /// Explicit specialization for short.
767  template<>
768    struct atomic<short> : __atomic_base<short>
769    {
770      typedef short 			__integral_type;
771      typedef __atomic_base<short> 		__base_type;
772
773      atomic() noexcept = default;
774      ~atomic() noexcept = default;
775      atomic(const atomic&) = delete;
776      atomic& operator=(const atomic&) = delete;
777      atomic& operator=(const atomic&) volatile = delete;
778
779      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
780
781      using __base_type::operator __integral_type;
782      using __base_type::operator=;
783
784#if __cplusplus >= 201703L
785    static constexpr bool is_always_lock_free = ATOMIC_SHORT_LOCK_FREE == 2;
786#endif
787    };
788
789  /// Explicit specialization for unsigned short.
790  template<>
791    struct atomic<unsigned short> : __atomic_base<unsigned short>
792    {
793      typedef unsigned short 	      	__integral_type;
794      typedef __atomic_base<unsigned short> 		__base_type;
795
796      atomic() noexcept = default;
797      ~atomic() noexcept = default;
798      atomic(const atomic&) = delete;
799      atomic& operator=(const atomic&) = delete;
800      atomic& operator=(const atomic&) volatile = delete;
801
802      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
803
804      using __base_type::operator __integral_type;
805      using __base_type::operator=;
806
807#if __cplusplus >= 201703L
808    static constexpr bool is_always_lock_free = ATOMIC_SHORT_LOCK_FREE == 2;
809#endif
810    };
811
812  /// Explicit specialization for int.
813  template<>
814    struct atomic<int> : __atomic_base<int>
815    {
816      typedef int 			__integral_type;
817      typedef __atomic_base<int> 		__base_type;
818
819      atomic() noexcept = default;
820      ~atomic() noexcept = default;
821      atomic(const atomic&) = delete;
822      atomic& operator=(const atomic&) = delete;
823      atomic& operator=(const atomic&) volatile = delete;
824
825      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
826
827      using __base_type::operator __integral_type;
828      using __base_type::operator=;
829
830#if __cplusplus >= 201703L
831    static constexpr bool is_always_lock_free = ATOMIC_INT_LOCK_FREE == 2;
832#endif
833    };
834
835  /// Explicit specialization for unsigned int.
836  template<>
837    struct atomic<unsigned int> : __atomic_base<unsigned int>
838    {
839      typedef unsigned int		__integral_type;
840      typedef __atomic_base<unsigned int> 	__base_type;
841
842      atomic() noexcept = default;
843      ~atomic() noexcept = default;
844      atomic(const atomic&) = delete;
845      atomic& operator=(const atomic&) = delete;
846      atomic& operator=(const atomic&) volatile = delete;
847
848      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
849
850      using __base_type::operator __integral_type;
851      using __base_type::operator=;
852
853#if __cplusplus >= 201703L
854    static constexpr bool is_always_lock_free = ATOMIC_INT_LOCK_FREE == 2;
855#endif
856    };
857
858  /// Explicit specialization for long.
859  template<>
860    struct atomic<long> : __atomic_base<long>
861    {
862      typedef long 			__integral_type;
863      typedef __atomic_base<long> 	__base_type;
864
865      atomic() noexcept = default;
866      ~atomic() noexcept = default;
867      atomic(const atomic&) = delete;
868      atomic& operator=(const atomic&) = delete;
869      atomic& operator=(const atomic&) volatile = delete;
870
871      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
872
873      using __base_type::operator __integral_type;
874      using __base_type::operator=;
875
876#if __cplusplus >= 201703L
877    static constexpr bool is_always_lock_free = ATOMIC_LONG_LOCK_FREE == 2;
878#endif
879    };
880
881  /// Explicit specialization for unsigned long.
882  template<>
883    struct atomic<unsigned long> : __atomic_base<unsigned long>
884    {
885      typedef unsigned long 		__integral_type;
886      typedef __atomic_base<unsigned long> 	__base_type;
887
888      atomic() noexcept = default;
889      ~atomic() noexcept = default;
890      atomic(const atomic&) = delete;
891      atomic& operator=(const atomic&) = delete;
892      atomic& operator=(const atomic&) volatile = delete;
893
894      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
895
896      using __base_type::operator __integral_type;
897      using __base_type::operator=;
898
899#if __cplusplus >= 201703L
900    static constexpr bool is_always_lock_free = ATOMIC_LONG_LOCK_FREE == 2;
901#endif
902    };
903
904  /// Explicit specialization for long long.
905  template<>
906    struct atomic<long long> : __atomic_base<long long>
907    {
908      typedef long long 		__integral_type;
909      typedef __atomic_base<long long> 		__base_type;
910
911      atomic() noexcept = default;
912      ~atomic() noexcept = default;
913      atomic(const atomic&) = delete;
914      atomic& operator=(const atomic&) = delete;
915      atomic& operator=(const atomic&) volatile = delete;
916
917      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
918
919      using __base_type::operator __integral_type;
920      using __base_type::operator=;
921
922#if __cplusplus >= 201703L
923    static constexpr bool is_always_lock_free = ATOMIC_LLONG_LOCK_FREE == 2;
924#endif
925    };
926
927  /// Explicit specialization for unsigned long long.
928  template<>
929    struct atomic<unsigned long long> : __atomic_base<unsigned long long>
930    {
931      typedef unsigned long long       	__integral_type;
932      typedef __atomic_base<unsigned long long> 	__base_type;
933
934      atomic() noexcept = default;
935      ~atomic() noexcept = default;
936      atomic(const atomic&) = delete;
937      atomic& operator=(const atomic&) = delete;
938      atomic& operator=(const atomic&) volatile = delete;
939
940      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
941
942      using __base_type::operator __integral_type;
943      using __base_type::operator=;
944
945#if __cplusplus >= 201703L
946    static constexpr bool is_always_lock_free = ATOMIC_LLONG_LOCK_FREE == 2;
947#endif
948    };
949
950  /// Explicit specialization for wchar_t.
951  template<>
952    struct atomic<wchar_t> : __atomic_base<wchar_t>
953    {
954      typedef wchar_t 			__integral_type;
955      typedef __atomic_base<wchar_t> 	__base_type;
956
957      atomic() noexcept = default;
958      ~atomic() noexcept = default;
959      atomic(const atomic&) = delete;
960      atomic& operator=(const atomic&) = delete;
961      atomic& operator=(const atomic&) volatile = delete;
962
963      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
964
965      using __base_type::operator __integral_type;
966      using __base_type::operator=;
967
968#if __cplusplus >= 201703L
969    static constexpr bool is_always_lock_free = ATOMIC_WCHAR_T_LOCK_FREE == 2;
970#endif
971    };
972
973#ifdef _GLIBCXX_USE_CHAR8_T
974  /// Explicit specialization for char8_t.
975  template<>
976    struct atomic<char8_t> : __atomic_base<char8_t>
977    {
978      typedef char8_t 			__integral_type;
979      typedef __atomic_base<char8_t> 	__base_type;
980
981      atomic() noexcept = default;
982      ~atomic() noexcept = default;
983      atomic(const atomic&) = delete;
984      atomic& operator=(const atomic&) = delete;
985      atomic& operator=(const atomic&) volatile = delete;
986
987      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
988
989      using __base_type::operator __integral_type;
990      using __base_type::operator=;
991
992#if __cplusplus > 201402L
993    static constexpr bool is_always_lock_free = ATOMIC_CHAR8_T_LOCK_FREE == 2;
994#endif
995    };
996#endif
997
998  /// Explicit specialization for char16_t.
999  template<>
1000    struct atomic<char16_t> : __atomic_base<char16_t>
1001    {
1002      typedef char16_t 			__integral_type;
1003      typedef __atomic_base<char16_t> 	__base_type;
1004
1005      atomic() noexcept = default;
1006      ~atomic() noexcept = default;
1007      atomic(const atomic&) = delete;
1008      atomic& operator=(const atomic&) = delete;
1009      atomic& operator=(const atomic&) volatile = delete;
1010
1011      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
1012
1013      using __base_type::operator __integral_type;
1014      using __base_type::operator=;
1015
1016#if __cplusplus >= 201703L
1017    static constexpr bool is_always_lock_free = ATOMIC_CHAR16_T_LOCK_FREE == 2;
1018#endif
1019    };
1020
1021  /// Explicit specialization for char32_t.
1022  template<>
1023    struct atomic<char32_t> : __atomic_base<char32_t>
1024    {
1025      typedef char32_t 			__integral_type;
1026      typedef __atomic_base<char32_t> 	__base_type;
1027
1028      atomic() noexcept = default;
1029      ~atomic() noexcept = default;
1030      atomic(const atomic&) = delete;
1031      atomic& operator=(const atomic&) = delete;
1032      atomic& operator=(const atomic&) volatile = delete;
1033
1034      constexpr atomic(__integral_type __i) noexcept : __base_type(__i) { }
1035
1036      using __base_type::operator __integral_type;
1037      using __base_type::operator=;
1038
1039#if __cplusplus >= 201703L
1040    static constexpr bool is_always_lock_free = ATOMIC_CHAR32_T_LOCK_FREE == 2;
1041#endif
1042    };
1043
1044
1045  /// atomic_bool
1046  typedef atomic<bool>			atomic_bool;
1047
1048  /// atomic_char
1049  typedef atomic<char>			atomic_char;
1050
1051  /// atomic_schar
1052  typedef atomic<signed char>		atomic_schar;
1053
1054  /// atomic_uchar
1055  typedef atomic<unsigned char>		atomic_uchar;
1056
1057  /// atomic_short
1058  typedef atomic<short>			atomic_short;
1059
1060  /// atomic_ushort
1061  typedef atomic<unsigned short>	atomic_ushort;
1062
1063  /// atomic_int
1064  typedef atomic<int>			atomic_int;
1065
1066  /// atomic_uint
1067  typedef atomic<unsigned int>		atomic_uint;
1068
1069  /// atomic_long
1070  typedef atomic<long>			atomic_long;
1071
1072  /// atomic_ulong
1073  typedef atomic<unsigned long>		atomic_ulong;
1074
1075  /// atomic_llong
1076  typedef atomic<long long>		atomic_llong;
1077
1078  /// atomic_ullong
1079  typedef atomic<unsigned long long>	atomic_ullong;
1080
1081  /// atomic_wchar_t
1082  typedef atomic<wchar_t>		atomic_wchar_t;
1083
1084#ifdef _GLIBCXX_USE_CHAR8_T
1085  /// atomic_char8_t
1086  typedef atomic<char8_t>		atomic_char8_t;
1087#endif
1088
1089  /// atomic_char16_t
1090  typedef atomic<char16_t>		atomic_char16_t;
1091
1092  /// atomic_char32_t
1093  typedef atomic<char32_t>		atomic_char32_t;
1094
1095#ifdef _GLIBCXX_USE_C99_STDINT_TR1
1096  // _GLIBCXX_RESOLVE_LIB_DEFECTS
1097  // 2441. Exact-width atomic typedefs should be provided
1098
1099  /// atomic_int8_t
1100  typedef atomic<int8_t>		atomic_int8_t;
1101
1102  /// atomic_uint8_t
1103  typedef atomic<uint8_t>		atomic_uint8_t;
1104
1105  /// atomic_int16_t
1106  typedef atomic<int16_t>		atomic_int16_t;
1107
1108  /// atomic_uint16_t
1109  typedef atomic<uint16_t>		atomic_uint16_t;
1110
1111  /// atomic_int32_t
1112  typedef atomic<int32_t>		atomic_int32_t;
1113
1114  /// atomic_uint32_t
1115  typedef atomic<uint32_t>		atomic_uint32_t;
1116
1117  /// atomic_int64_t
1118  typedef atomic<int64_t>		atomic_int64_t;
1119
1120  /// atomic_uint64_t
1121  typedef atomic<uint64_t>		atomic_uint64_t;
1122
1123
1124  /// atomic_int_least8_t
1125  typedef atomic<int_least8_t>		atomic_int_least8_t;
1126
1127  /// atomic_uint_least8_t
1128  typedef atomic<uint_least8_t>		atomic_uint_least8_t;
1129
1130  /// atomic_int_least16_t
1131  typedef atomic<int_least16_t>		atomic_int_least16_t;
1132
1133  /// atomic_uint_least16_t
1134  typedef atomic<uint_least16_t>	atomic_uint_least16_t;
1135
1136  /// atomic_int_least32_t
1137  typedef atomic<int_least32_t>		atomic_int_least32_t;
1138
1139  /// atomic_uint_least32_t
1140  typedef atomic<uint_least32_t>	atomic_uint_least32_t;
1141
1142  /// atomic_int_least64_t
1143  typedef atomic<int_least64_t>		atomic_int_least64_t;
1144
1145  /// atomic_uint_least64_t
1146  typedef atomic<uint_least64_t>	atomic_uint_least64_t;
1147
1148
1149  /// atomic_int_fast8_t
1150  typedef atomic<int_fast8_t>		atomic_int_fast8_t;
1151
1152  /// atomic_uint_fast8_t
1153  typedef atomic<uint_fast8_t>		atomic_uint_fast8_t;
1154
1155  /// atomic_int_fast16_t
1156  typedef atomic<int_fast16_t>		atomic_int_fast16_t;
1157
1158  /// atomic_uint_fast16_t
1159  typedef atomic<uint_fast16_t>		atomic_uint_fast16_t;
1160
1161  /// atomic_int_fast32_t
1162  typedef atomic<int_fast32_t>		atomic_int_fast32_t;
1163
1164  /// atomic_uint_fast32_t
1165  typedef atomic<uint_fast32_t>		atomic_uint_fast32_t;
1166
1167  /// atomic_int_fast64_t
1168  typedef atomic<int_fast64_t>		atomic_int_fast64_t;
1169
1170  /// atomic_uint_fast64_t
1171  typedef atomic<uint_fast64_t>		atomic_uint_fast64_t;
1172#endif
1173
1174
1175  /// atomic_intptr_t
1176  typedef atomic<intptr_t>		atomic_intptr_t;
1177
1178  /// atomic_uintptr_t
1179  typedef atomic<uintptr_t>		atomic_uintptr_t;
1180
1181  /// atomic_size_t
1182  typedef atomic<size_t>		atomic_size_t;
1183
1184  /// atomic_ptrdiff_t
1185  typedef atomic<ptrdiff_t>		atomic_ptrdiff_t;
1186
1187#ifdef _GLIBCXX_USE_C99_STDINT_TR1
1188  /// atomic_intmax_t
1189  typedef atomic<intmax_t>		atomic_intmax_t;
1190
1191  /// atomic_uintmax_t
1192  typedef atomic<uintmax_t>		atomic_uintmax_t;
1193#endif
1194
1195  // Function definitions, atomic_flag operations.
1196  inline bool
1197  atomic_flag_test_and_set_explicit(atomic_flag* __a,
1198				    memory_order __m) noexcept
1199  { return __a->test_and_set(__m); }
1200
1201  inline bool
1202  atomic_flag_test_and_set_explicit(volatile atomic_flag* __a,
1203				    memory_order __m) noexcept
1204  { return __a->test_and_set(__m); }
1205
1206  inline void
1207  atomic_flag_clear_explicit(atomic_flag* __a, memory_order __m) noexcept
1208  { __a->clear(__m); }
1209
1210  inline void
1211  atomic_flag_clear_explicit(volatile atomic_flag* __a,
1212			     memory_order __m) noexcept
1213  { __a->clear(__m); }
1214
1215  inline bool
1216  atomic_flag_test_and_set(atomic_flag* __a) noexcept
1217  { return atomic_flag_test_and_set_explicit(__a, memory_order_seq_cst); }
1218
1219  inline bool
1220  atomic_flag_test_and_set(volatile atomic_flag* __a) noexcept
1221  { return atomic_flag_test_and_set_explicit(__a, memory_order_seq_cst); }
1222
1223  inline void
1224  atomic_flag_clear(atomic_flag* __a) noexcept
1225  { atomic_flag_clear_explicit(__a, memory_order_seq_cst); }
1226
1227  inline void
1228  atomic_flag_clear(volatile atomic_flag* __a) noexcept
1229  { atomic_flag_clear_explicit(__a, memory_order_seq_cst); }
1230
1231
1232  template<typename _Tp>
1233    using __atomic_val_t = typename atomic<_Tp>::value_type;
1234  template<typename _Tp>
1235    using __atomic_diff_t = typename atomic<_Tp>::difference_type;
1236
1237  // [atomics.nonmembers] Non-member functions.
1238  // Function templates generally applicable to atomic types.
1239  template<typename _ITp>
1240    inline bool
1241    atomic_is_lock_free(const atomic<_ITp>* __a) noexcept
1242    { return __a->is_lock_free(); }
1243
1244  template<typename _ITp>
1245    inline bool
1246    atomic_is_lock_free(const volatile atomic<_ITp>* __a) noexcept
1247    { return __a->is_lock_free(); }
1248
1249  template<typename _ITp>
1250    inline void
1251    atomic_init(atomic<_ITp>* __a, __atomic_val_t<_ITp> __i) noexcept
1252    { __a->store(__i, memory_order_relaxed); }
1253
1254  template<typename _ITp>
1255    inline void
1256    atomic_init(volatile atomic<_ITp>* __a, __atomic_val_t<_ITp> __i) noexcept
1257    { __a->store(__i, memory_order_relaxed); }
1258
1259  template<typename _ITp>
1260    inline void
1261    atomic_store_explicit(atomic<_ITp>* __a, __atomic_val_t<_ITp> __i,
1262			  memory_order __m) noexcept
1263    { __a->store(__i, __m); }
1264
1265  template<typename _ITp>
1266    inline void
1267    atomic_store_explicit(volatile atomic<_ITp>* __a, __atomic_val_t<_ITp> __i,
1268			  memory_order __m) noexcept
1269    { __a->store(__i, __m); }
1270
1271  template<typename _ITp>
1272    inline _ITp
1273    atomic_load_explicit(const atomic<_ITp>* __a, memory_order __m) noexcept
1274    { return __a->load(__m); }
1275
1276  template<typename _ITp>
1277    inline _ITp
1278    atomic_load_explicit(const volatile atomic<_ITp>* __a,
1279			 memory_order __m) noexcept
1280    { return __a->load(__m); }
1281
1282  template<typename _ITp>
1283    inline _ITp
1284    atomic_exchange_explicit(atomic<_ITp>* __a, __atomic_val_t<_ITp> __i,
1285			     memory_order __m) noexcept
1286    { return __a->exchange(__i, __m); }
1287
1288  template<typename _ITp>
1289    inline _ITp
1290    atomic_exchange_explicit(volatile atomic<_ITp>* __a,
1291			     __atomic_val_t<_ITp> __i,
1292			     memory_order __m) noexcept
1293    { return __a->exchange(__i, __m); }
1294
1295  template<typename _ITp>
1296    inline bool
1297    atomic_compare_exchange_weak_explicit(atomic<_ITp>* __a,
1298					  __atomic_val_t<_ITp>* __i1,
1299					  __atomic_val_t<_ITp> __i2,
1300					  memory_order __m1,
1301					  memory_order __m2) noexcept
1302    { return __a->compare_exchange_weak(*__i1, __i2, __m1, __m2); }
1303
1304  template<typename _ITp>
1305    inline bool
1306    atomic_compare_exchange_weak_explicit(volatile atomic<_ITp>* __a,
1307					  __atomic_val_t<_ITp>* __i1,
1308					  __atomic_val_t<_ITp> __i2,
1309					  memory_order __m1,
1310					  memory_order __m2) noexcept
1311    { return __a->compare_exchange_weak(*__i1, __i2, __m1, __m2); }
1312
1313  template<typename _ITp>
1314    inline bool
1315    atomic_compare_exchange_strong_explicit(atomic<_ITp>* __a,
1316					    __atomic_val_t<_ITp>* __i1,
1317					    __atomic_val_t<_ITp> __i2,
1318					    memory_order __m1,
1319					    memory_order __m2) noexcept
1320    { return __a->compare_exchange_strong(*__i1, __i2, __m1, __m2); }
1321
1322  template<typename _ITp>
1323    inline bool
1324    atomic_compare_exchange_strong_explicit(volatile atomic<_ITp>* __a,
1325					    __atomic_val_t<_ITp>* __i1,
1326					    __atomic_val_t<_ITp> __i2,
1327					    memory_order __m1,
1328					    memory_order __m2) noexcept
1329    { return __a->compare_exchange_strong(*__i1, __i2, __m1, __m2); }
1330
1331
1332  template<typename _ITp>
1333    inline void
1334    atomic_store(atomic<_ITp>* __a, __atomic_val_t<_ITp> __i) noexcept
1335    { atomic_store_explicit(__a, __i, memory_order_seq_cst); }
1336
1337  template<typename _ITp>
1338    inline void
1339    atomic_store(volatile atomic<_ITp>* __a, __atomic_val_t<_ITp> __i) noexcept
1340    { atomic_store_explicit(__a, __i, memory_order_seq_cst); }
1341
1342  template<typename _ITp>
1343    inline _ITp
1344    atomic_load(const atomic<_ITp>* __a) noexcept
1345    { return atomic_load_explicit(__a, memory_order_seq_cst); }
1346
1347  template<typename _ITp>
1348    inline _ITp
1349    atomic_load(const volatile atomic<_ITp>* __a) noexcept
1350    { return atomic_load_explicit(__a, memory_order_seq_cst); }
1351
1352  template<typename _ITp>
1353    inline _ITp
1354    atomic_exchange(atomic<_ITp>* __a, __atomic_val_t<_ITp> __i) noexcept
1355    { return atomic_exchange_explicit(__a, __i, memory_order_seq_cst); }
1356
1357  template<typename _ITp>
1358    inline _ITp
1359    atomic_exchange(volatile atomic<_ITp>* __a,
1360		    __atomic_val_t<_ITp> __i) noexcept
1361    { return atomic_exchange_explicit(__a, __i, memory_order_seq_cst); }
1362
1363  template<typename _ITp>
1364    inline bool
1365    atomic_compare_exchange_weak(atomic<_ITp>* __a,
1366				 __atomic_val_t<_ITp>* __i1,
1367				 __atomic_val_t<_ITp> __i2) noexcept
1368    {
1369      return atomic_compare_exchange_weak_explicit(__a, __i1, __i2,
1370						   memory_order_seq_cst,
1371						   memory_order_seq_cst);
1372    }
1373
1374  template<typename _ITp>
1375    inline bool
1376    atomic_compare_exchange_weak(volatile atomic<_ITp>* __a,
1377				 __atomic_val_t<_ITp>* __i1,
1378				 __atomic_val_t<_ITp> __i2) noexcept
1379    {
1380      return atomic_compare_exchange_weak_explicit(__a, __i1, __i2,
1381						   memory_order_seq_cst,
1382						   memory_order_seq_cst);
1383    }
1384
1385  template<typename _ITp>
1386    inline bool
1387    atomic_compare_exchange_strong(atomic<_ITp>* __a,
1388				   __atomic_val_t<_ITp>* __i1,
1389				   __atomic_val_t<_ITp> __i2) noexcept
1390    {
1391      return atomic_compare_exchange_strong_explicit(__a, __i1, __i2,
1392						     memory_order_seq_cst,
1393						     memory_order_seq_cst);
1394    }
1395
1396  template<typename _ITp>
1397    inline bool
1398    atomic_compare_exchange_strong(volatile atomic<_ITp>* __a,
1399				   __atomic_val_t<_ITp>* __i1,
1400				   __atomic_val_t<_ITp> __i2) noexcept
1401    {
1402      return atomic_compare_exchange_strong_explicit(__a, __i1, __i2,
1403						     memory_order_seq_cst,
1404						     memory_order_seq_cst);
1405    }
1406
1407
1408#if __cpp_lib_atomic_wait
1409  template<typename _Tp>
1410    inline void
1411    atomic_wait(const atomic<_Tp>* __a,
1412	        typename std::atomic<_Tp>::value_type __old) noexcept
1413    { __a->wait(__old); }
1414
1415  template<typename _Tp>
1416    inline void
1417    atomic_wait_explicit(const atomic<_Tp>* __a,
1418			 typename std::atomic<_Tp>::value_type __old,
1419			 std::memory_order __m) noexcept
1420    { __a->wait(__old, __m); }
1421
1422  template<typename _Tp>
1423    inline void
1424    atomic_notify_one(atomic<_Tp>* __a) noexcept
1425    { __a->notify_one(); }
1426
1427  template<typename _Tp>
1428    inline void
1429    atomic_notify_all(atomic<_Tp>* __a) noexcept
1430    { __a->notify_all(); }
1431#endif // __cpp_lib_atomic_wait
1432
1433  // Function templates for atomic_integral and atomic_pointer operations only.
1434  // Some operations (and, or, xor) are only available for atomic integrals,
1435  // which is implemented by taking a parameter of type __atomic_base<_ITp>*.
1436
1437  template<typename _ITp>
1438    inline _ITp
1439    atomic_fetch_add_explicit(atomic<_ITp>* __a,
1440			      __atomic_diff_t<_ITp> __i,
1441			      memory_order __m) noexcept
1442    { return __a->fetch_add(__i, __m); }
1443
1444  template<typename _ITp>
1445    inline _ITp
1446    atomic_fetch_add_explicit(volatile atomic<_ITp>* __a,
1447			      __atomic_diff_t<_ITp> __i,
1448			      memory_order __m) noexcept
1449    { return __a->fetch_add(__i, __m); }
1450
1451  template<typename _ITp>
1452    inline _ITp
1453    atomic_fetch_sub_explicit(atomic<_ITp>* __a,
1454			      __atomic_diff_t<_ITp> __i,
1455			      memory_order __m) noexcept
1456    { return __a->fetch_sub(__i, __m); }
1457
1458  template<typename _ITp>
1459    inline _ITp
1460    atomic_fetch_sub_explicit(volatile atomic<_ITp>* __a,
1461			      __atomic_diff_t<_ITp> __i,
1462			      memory_order __m) noexcept
1463    { return __a->fetch_sub(__i, __m); }
1464
1465  template<typename _ITp>
1466    inline _ITp
1467    atomic_fetch_and_explicit(__atomic_base<_ITp>* __a,
1468			      __atomic_val_t<_ITp> __i,
1469			      memory_order __m) noexcept
1470    { return __a->fetch_and(__i, __m); }
1471
1472  template<typename _ITp>
1473    inline _ITp
1474    atomic_fetch_and_explicit(volatile __atomic_base<_ITp>* __a,
1475			      __atomic_val_t<_ITp> __i,
1476			      memory_order __m) noexcept
1477    { return __a->fetch_and(__i, __m); }
1478
1479  template<typename _ITp>
1480    inline _ITp
1481    atomic_fetch_or_explicit(__atomic_base<_ITp>* __a,
1482			     __atomic_val_t<_ITp> __i,
1483			     memory_order __m) noexcept
1484    { return __a->fetch_or(__i, __m); }
1485
1486  template<typename _ITp>
1487    inline _ITp
1488    atomic_fetch_or_explicit(volatile __atomic_base<_ITp>* __a,
1489			     __atomic_val_t<_ITp> __i,
1490			     memory_order __m) noexcept
1491    { return __a->fetch_or(__i, __m); }
1492
1493  template<typename _ITp>
1494    inline _ITp
1495    atomic_fetch_xor_explicit(__atomic_base<_ITp>* __a,
1496			      __atomic_val_t<_ITp> __i,
1497			      memory_order __m) noexcept
1498    { return __a->fetch_xor(__i, __m); }
1499
1500  template<typename _ITp>
1501    inline _ITp
1502    atomic_fetch_xor_explicit(volatile __atomic_base<_ITp>* __a,
1503			      __atomic_val_t<_ITp> __i,
1504			      memory_order __m) noexcept
1505    { return __a->fetch_xor(__i, __m); }
1506
1507  template<typename _ITp>
1508    inline _ITp
1509    atomic_fetch_add(atomic<_ITp>* __a,
1510		     __atomic_diff_t<_ITp> __i) noexcept
1511    { return atomic_fetch_add_explicit(__a, __i, memory_order_seq_cst); }
1512
1513  template<typename _ITp>
1514    inline _ITp
1515    atomic_fetch_add(volatile atomic<_ITp>* __a,
1516		     __atomic_diff_t<_ITp> __i) noexcept
1517    { return atomic_fetch_add_explicit(__a, __i, memory_order_seq_cst); }
1518
1519  template<typename _ITp>
1520    inline _ITp
1521    atomic_fetch_sub(atomic<_ITp>* __a,
1522		     __atomic_diff_t<_ITp> __i) noexcept
1523    { return atomic_fetch_sub_explicit(__a, __i, memory_order_seq_cst); }
1524
1525  template<typename _ITp>
1526    inline _ITp
1527    atomic_fetch_sub(volatile atomic<_ITp>* __a,
1528		     __atomic_diff_t<_ITp> __i) noexcept
1529    { return atomic_fetch_sub_explicit(__a, __i, memory_order_seq_cst); }
1530
1531  template<typename _ITp>
1532    inline _ITp
1533    atomic_fetch_and(__atomic_base<_ITp>* __a,
1534		     __atomic_val_t<_ITp> __i) noexcept
1535    { return atomic_fetch_and_explicit(__a, __i, memory_order_seq_cst); }
1536
1537  template<typename _ITp>
1538    inline _ITp
1539    atomic_fetch_and(volatile __atomic_base<_ITp>* __a,
1540		     __atomic_val_t<_ITp> __i) noexcept
1541    { return atomic_fetch_and_explicit(__a, __i, memory_order_seq_cst); }
1542
1543  template<typename _ITp>
1544    inline _ITp
1545    atomic_fetch_or(__atomic_base<_ITp>* __a,
1546		    __atomic_val_t<_ITp> __i) noexcept
1547    { return atomic_fetch_or_explicit(__a, __i, memory_order_seq_cst); }
1548
1549  template<typename _ITp>
1550    inline _ITp
1551    atomic_fetch_or(volatile __atomic_base<_ITp>* __a,
1552		    __atomic_val_t<_ITp> __i) noexcept
1553    { return atomic_fetch_or_explicit(__a, __i, memory_order_seq_cst); }
1554
1555  template<typename _ITp>
1556    inline _ITp
1557    atomic_fetch_xor(__atomic_base<_ITp>* __a,
1558		     __atomic_val_t<_ITp> __i) noexcept
1559    { return atomic_fetch_xor_explicit(__a, __i, memory_order_seq_cst); }
1560
1561  template<typename _ITp>
1562    inline _ITp
1563    atomic_fetch_xor(volatile __atomic_base<_ITp>* __a,
1564		     __atomic_val_t<_ITp> __i) noexcept
1565    { return atomic_fetch_xor_explicit(__a, __i, memory_order_seq_cst); }
1566
1567#if __cplusplus > 201703L
1568#define __cpp_lib_atomic_float 201711L
1569  template<>
1570    struct atomic<float> : __atomic_float<float>
1571    {
1572      atomic() noexcept = default;
1573
1574      constexpr
1575      atomic(float __fp) noexcept : __atomic_float<float>(__fp)
1576      { }
1577
1578      atomic& operator=(const atomic&) volatile = delete;
1579      atomic& operator=(const atomic&) = delete;
1580
1581      using __atomic_float<float>::operator=;
1582    };
1583
1584  template<>
1585    struct atomic<double> : __atomic_float<double>
1586    {
1587      atomic() noexcept = default;
1588
1589      constexpr
1590      atomic(double __fp) noexcept : __atomic_float<double>(__fp)
1591      { }
1592
1593      atomic& operator=(const atomic&) volatile = delete;
1594      atomic& operator=(const atomic&) = delete;
1595
1596      using __atomic_float<double>::operator=;
1597    };
1598
1599  template<>
1600    struct atomic<long double> : __atomic_float<long double>
1601    {
1602      atomic() noexcept = default;
1603
1604      constexpr
1605      atomic(long double __fp) noexcept : __atomic_float<long double>(__fp)
1606      { }
1607
1608      atomic& operator=(const atomic&) volatile = delete;
1609      atomic& operator=(const atomic&) = delete;
1610
1611      using __atomic_float<long double>::operator=;
1612    };
1613
1614#define __cpp_lib_atomic_ref 201806L
1615
1616  /// Class template to provide atomic operations on a non-atomic variable.
1617  template<typename _Tp>
1618    struct atomic_ref : __atomic_ref<_Tp>
1619    {
1620      explicit
1621      atomic_ref(_Tp& __t) noexcept : __atomic_ref<_Tp>(__t)
1622      { }
1623
1624      atomic_ref& operator=(const atomic_ref&) = delete;
1625
1626      atomic_ref(const atomic_ref&) = default;
1627
1628      using __atomic_ref<_Tp>::operator=;
1629    };
1630
1631#endif // C++2a
1632
1633  /// @} group atomics
1634
1635_GLIBCXX_END_NAMESPACE_VERSION
1636} // namespace
1637
1638#endif // C++11
1639
1640#endif // _GLIBCXX_ATOMIC
1641