diff --git a/contrib/llvm-project/libcxx/include/atomic b/contrib/llvm-project/libcxx/include/atomic
index 9c2898653788..2dfb6f7b8131 100644
--- a/contrib/llvm-project/libcxx/include/atomic
+++ b/contrib/llvm-project/libcxx/include/atomic
@@ -1,2788 +1,2788 @@
 // -*- C++ -*-
 //===--------------------------- atomic -----------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef _LIBCPP_ATOMIC
 #define _LIBCPP_ATOMIC
 
 /*
     atomic synopsis
 
 namespace std
 {
 
 // feature test macro
 
 #define __cpp_lib_atomic_is_always_lock_free // as specified by SG10
 
  // order and consistency
 
  enum memory_order: unspecified // enum class in C++20
  {
     relaxed,
     consume, // load-consume
     acquire, // load-acquire
     release, // store-release
     acq_rel, // store-release load-acquire
     seq_cst // store-release load-acquire
  };
 
  inline constexpr auto memory_order_relaxed = memory_order::relaxed;
  inline constexpr auto memory_order_consume = memory_order::consume;
  inline constexpr auto memory_order_acquire = memory_order::acquire;
  inline constexpr auto memory_order_release = memory_order::release;
  inline constexpr auto memory_order_acq_rel = memory_order::acq_rel;
  inline constexpr auto memory_order_seq_cst = memory_order::seq_cst;
 
 template <class T> T kill_dependency(T y) noexcept;
 
 // lock-free property
 
 #define ATOMIC_BOOL_LOCK_FREE unspecified
 #define ATOMIC_CHAR_LOCK_FREE unspecified
 #define ATOMIC_CHAR16_T_LOCK_FREE unspecified
 #define ATOMIC_CHAR32_T_LOCK_FREE unspecified
 #define ATOMIC_WCHAR_T_LOCK_FREE unspecified
 #define ATOMIC_SHORT_LOCK_FREE unspecified
 #define ATOMIC_INT_LOCK_FREE unspecified
 #define ATOMIC_LONG_LOCK_FREE unspecified
 #define ATOMIC_LLONG_LOCK_FREE unspecified
 #define ATOMIC_POINTER_LOCK_FREE unspecified
 
 template <class T>
 struct atomic
 {
     using value_type = T;
 
     static constexpr bool is_always_lock_free;
     bool is_lock_free() const volatile noexcept;
     bool is_lock_free() const noexcept;
 
     atomic() noexcept = default;
     constexpr atomic(T desr) noexcept;
     atomic(const atomic&) = delete;
     atomic& operator=(const atomic&) = delete;
     atomic& operator=(const atomic&) volatile = delete;
 
     T load(memory_order m = memory_order_seq_cst) const volatile noexcept;
     T load(memory_order m = memory_order_seq_cst) const noexcept;
     operator T() const volatile noexcept;
     operator T() const noexcept;
     void store(T desr, memory_order m = memory_order_seq_cst) volatile noexcept;
     void store(T desr, memory_order m = memory_order_seq_cst) noexcept;
     T operator=(T) volatile noexcept;
     T operator=(T) noexcept;
 
     T exchange(T desr, memory_order m = memory_order_seq_cst) volatile noexcept;
     T exchange(T desr, memory_order m = memory_order_seq_cst) noexcept;
     bool compare_exchange_weak(T& expc, T desr,
                                memory_order s, memory_order f) volatile noexcept;
     bool compare_exchange_weak(T& expc, T desr, memory_order s, memory_order f) noexcept;
     bool compare_exchange_strong(T& expc, T desr,
                                  memory_order s, memory_order f) volatile noexcept;
     bool compare_exchange_strong(T& expc, T desr,
                                  memory_order s, memory_order f) noexcept;
     bool compare_exchange_weak(T& expc, T desr,
                                memory_order m = memory_order_seq_cst) volatile noexcept;
     bool compare_exchange_weak(T& expc, T desr,
                                memory_order m = memory_order_seq_cst) noexcept;
     bool compare_exchange_strong(T& expc, T desr,
                                 memory_order m = memory_order_seq_cst) volatile noexcept;
     bool compare_exchange_strong(T& expc, T desr,
                                  memory_order m = memory_order_seq_cst) noexcept;
 
     void wait(T, memory_order = memory_order::seq_cst) const volatile noexcept;
     void wait(T, memory_order = memory_order::seq_cst) const noexcept;
     void notify_one() volatile noexcept;
     void notify_one() noexcept;
     void notify_all() volatile noexcept;
     void notify_all() noexcept;
 };
 
 template <>
 struct atomic<integral>
 {
     using value_type = integral;
 
     static constexpr bool is_always_lock_free;
     bool is_lock_free() const volatile noexcept;
     bool is_lock_free() const noexcept;
 
     atomic() noexcept = default;
     constexpr atomic(integral desr) noexcept;
     atomic(const atomic&) = delete;
     atomic& operator=(const atomic&) = delete;
     atomic& operator=(const atomic&) volatile = delete;
 
     integral load(memory_order m = memory_order_seq_cst) const volatile noexcept;
     integral load(memory_order m = memory_order_seq_cst) const noexcept;
     operator integral() const volatile noexcept;
     operator integral() const noexcept;
     void store(integral desr, memory_order m = memory_order_seq_cst) volatile noexcept;
     void store(integral desr, memory_order m = memory_order_seq_cst) noexcept;
     integral operator=(integral desr) volatile noexcept;
     integral operator=(integral desr) noexcept;
 
     integral exchange(integral desr,
                       memory_order m = memory_order_seq_cst) volatile noexcept;
     integral exchange(integral desr, memory_order m = memory_order_seq_cst) noexcept;
     bool compare_exchange_weak(integral& expc, integral desr,
                                memory_order s, memory_order f) volatile noexcept;
     bool compare_exchange_weak(integral& expc, integral desr,
                                memory_order s, memory_order f) noexcept;
     bool compare_exchange_strong(integral& expc, integral desr,
                                  memory_order s, memory_order f) volatile noexcept;
     bool compare_exchange_strong(integral& expc, integral desr,
                                  memory_order s, memory_order f) noexcept;
     bool compare_exchange_weak(integral& expc, integral desr,
                                memory_order m = memory_order_seq_cst) volatile noexcept;
     bool compare_exchange_weak(integral& expc, integral desr,
                                memory_order m = memory_order_seq_cst) noexcept;
     bool compare_exchange_strong(integral& expc, integral desr,
                                 memory_order m = memory_order_seq_cst) volatile noexcept;
     bool compare_exchange_strong(integral& expc, integral desr,
                                  memory_order m = memory_order_seq_cst) noexcept;
 
     integral fetch_add(integral op, memory_order m = memory_order_seq_cst) volatile noexcept;
     integral fetch_add(integral op, memory_order m = memory_order_seq_cst) noexcept;
     integral fetch_sub(integral op, memory_order m = memory_order_seq_cst) volatile noexcept;
     integral fetch_sub(integral op, memory_order m = memory_order_seq_cst) noexcept;
     integral fetch_and(integral op, memory_order m = memory_order_seq_cst) volatile noexcept;
     integral fetch_and(integral op, memory_order m = memory_order_seq_cst) noexcept;
     integral fetch_or(integral op, memory_order m = memory_order_seq_cst) volatile noexcept;
     integral fetch_or(integral op, memory_order m = memory_order_seq_cst) noexcept;
     integral fetch_xor(integral op, memory_order m = memory_order_seq_cst) volatile noexcept;
     integral fetch_xor(integral op, memory_order m = memory_order_seq_cst) noexcept;
 
     integral operator++(int) volatile noexcept;
     integral operator++(int) noexcept;
     integral operator--(int) volatile noexcept;
     integral operator--(int) noexcept;
     integral operator++() volatile noexcept;
     integral operator++() noexcept;
     integral operator--() volatile noexcept;
     integral operator--() noexcept;
     integral operator+=(integral op) volatile noexcept;
     integral operator+=(integral op) noexcept;
     integral operator-=(integral op) volatile noexcept;
     integral operator-=(integral op) noexcept;
     integral operator&=(integral op) volatile noexcept;
     integral operator&=(integral op) noexcept;
     integral operator|=(integral op) volatile noexcept;
     integral operator|=(integral op) noexcept;
     integral operator^=(integral op) volatile noexcept;
     integral operator^=(integral op) noexcept;
 
     void wait(integral, memory_order = memory_order::seq_cst) const volatile noexcept;
     void wait(integral, memory_order = memory_order::seq_cst) const noexcept;
     void notify_one() volatile noexcept;
     void notify_one() noexcept;
     void notify_all() volatile noexcept;
     void notify_all() noexcept;
 };
 
 template <class T>
 struct atomic<T*>
 {
     using value_type = T*;
 
     static constexpr bool is_always_lock_free;
     bool is_lock_free() const volatile noexcept;
     bool is_lock_free() const noexcept;
 
     atomic() noexcept = default;
     constexpr atomic(T* desr) noexcept;
     atomic(const atomic&) = delete;
     atomic& operator=(const atomic&) = delete;
     atomic& operator=(const atomic&) volatile = delete;
 
     T* load(memory_order m = memory_order_seq_cst) const volatile noexcept;
     T* load(memory_order m = memory_order_seq_cst) const noexcept;
     operator T*() const volatile noexcept;
     operator T*() const noexcept;
     void store(T* desr, memory_order m = memory_order_seq_cst) volatile noexcept;
     void store(T* desr, memory_order m = memory_order_seq_cst) noexcept;
     T* operator=(T*) volatile noexcept;
     T* operator=(T*) noexcept;
 
     T* exchange(T* desr, memory_order m = memory_order_seq_cst) volatile noexcept;
     T* exchange(T* desr, memory_order m = memory_order_seq_cst) noexcept;
     bool compare_exchange_weak(T*& expc, T* desr,
                                memory_order s, memory_order f) volatile noexcept;
     bool compare_exchange_weak(T*& expc, T* desr,
                                memory_order s, memory_order f) noexcept;
     bool compare_exchange_strong(T*& expc, T* desr,
                                  memory_order s, memory_order f) volatile noexcept;
     bool compare_exchange_strong(T*& expc, T* desr,
                                  memory_order s, memory_order f) noexcept;
     bool compare_exchange_weak(T*& expc, T* desr,
                                memory_order m = memory_order_seq_cst) volatile noexcept;
     bool compare_exchange_weak(T*& expc, T* desr,
                                memory_order m = memory_order_seq_cst) noexcept;
     bool compare_exchange_strong(T*& expc, T* desr,
                                 memory_order m = memory_order_seq_cst) volatile noexcept;
     bool compare_exchange_strong(T*& expc, T* desr,
                                  memory_order m = memory_order_seq_cst) noexcept;
     T* fetch_add(ptrdiff_t op, memory_order m = memory_order_seq_cst) volatile noexcept;
     T* fetch_add(ptrdiff_t op, memory_order m = memory_order_seq_cst) noexcept;
     T* fetch_sub(ptrdiff_t op, memory_order m = memory_order_seq_cst) volatile noexcept;
     T* fetch_sub(ptrdiff_t op, memory_order m = memory_order_seq_cst) noexcept;
 
     T* operator++(int) volatile noexcept;
     T* operator++(int) noexcept;
     T* operator--(int) volatile noexcept;
     T* operator--(int) noexcept;
     T* operator++() volatile noexcept;
     T* operator++() noexcept;
     T* operator--() volatile noexcept;
     T* operator--() noexcept;
     T* operator+=(ptrdiff_t op) volatile noexcept;
     T* operator+=(ptrdiff_t op) noexcept;
     T* operator-=(ptrdiff_t op) volatile noexcept;
     T* operator-=(ptrdiff_t op) noexcept;
 
     void wait(T*, memory_order = memory_order::seq_cst) const volatile noexcept;
     void wait(T*, memory_order = memory_order::seq_cst) const noexcept;
     void notify_one() volatile noexcept;
     void notify_one() noexcept;
     void notify_all() volatile noexcept;
     void notify_all() noexcept;
 };
 
 
 template <class T>
   bool atomic_is_lock_free(const volatile atomic<T>* obj) noexcept;
 
 template <class T>
   bool atomic_is_lock_free(const atomic<T>* obj) noexcept;
 
 template <class T>
   void atomic_store(volatile atomic<T>* obj, T desr) noexcept;
 
 template <class T>
   void atomic_store(atomic<T>* obj, T desr) noexcept;
 
 template <class T>
   void atomic_store_explicit(volatile atomic<T>* obj, T desr, memory_order m) noexcept;
 
 template <class T>
   void atomic_store_explicit(atomic<T>* obj, T desr, memory_order m) noexcept;
 
 template <class T>
   T atomic_load(const volatile atomic<T>* obj) noexcept;
 
 template <class T>
   T atomic_load(const atomic<T>* obj) noexcept;
 
 template <class T>
   T atomic_load_explicit(const volatile atomic<T>* obj, memory_order m) noexcept;
 
 template <class T>
   T atomic_load_explicit(const atomic<T>* obj, memory_order m) noexcept;
 
 template <class T>
   T atomic_exchange(volatile atomic<T>* obj, T desr) noexcept;
 
 template <class T>
   T atomic_exchange(atomic<T>* obj, T desr) noexcept;
 
 template <class T>
   T atomic_exchange_explicit(volatile atomic<T>* obj, T desr, memory_order m) noexcept;
 
 template <class T>
   T atomic_exchange_explicit(atomic<T>* obj, T desr, memory_order m) noexcept;
 
 template <class T>
   bool atomic_compare_exchange_weak(volatile atomic<T>* obj, T* expc, T desr) noexcept;
 
 template <class T>
   bool atomic_compare_exchange_weak(atomic<T>* obj, T* expc, T desr) noexcept;
 
 template <class T>
   bool atomic_compare_exchange_strong(volatile atomic<T>* obj, T* expc, T desr) noexcept;
 
 template <class T>
   bool atomic_compare_exchange_strong(atomic<T>* obj, T* expc, T desr) noexcept;
 
 template <class T>
   bool atomic_compare_exchange_weak_explicit(volatile atomic<T>* obj, T* expc,
                                              T desr,
                                              memory_order s, memory_order f) noexcept;
 
 template <class T>
   bool atomic_compare_exchange_weak_explicit(atomic<T>* obj, T* expc, T desr,
                                              memory_order s, memory_order f) noexcept;
 
 template <class T>
   bool atomic_compare_exchange_strong_explicit(volatile atomic<T>* obj,
                                                T* expc, T desr,
                                                memory_order s, memory_order f) noexcept;
 
 template <class T>
   bool atomic_compare_exchange_strong_explicit(atomic<T>* obj, T* expc,
                                                T desr,
                                                memory_order s, memory_order f) noexcept;
 
 template <class T>
   void atomic_wait(const volatile atomic<T>* obj, T old) noexcept;
 
 template <class T>
   void atomic_wait(const atomic<T>* obj, T old) noexcept;
 
 template <class T>
   void atomic_wait_explicit(const volatile atomic<T>* obj, T old, memory_order m) noexcept;
 
 template <class T>
   void atomic_wait_explicit(const atomic<T>* obj, T old, memory_order m) noexcept;
 
 template <class T>
   void atomic_one(volatile atomic<T>* obj) noexcept;
 
 template <class T>
   void atomic_one(atomic<T>* obj) noexcept;
 
 template <class T>
   void atomic_all(volatile atomic<T>* obj) noexcept;
 
 template <class T>
   void atomic_all(atomic<T>* obj) noexcept;
 
 template <class Integral>
   Integral atomic_fetch_add(volatile atomic<Integral>* obj, Integral op) noexcept;
 
 template <class Integral>
   Integral atomic_fetch_add(atomic<Integral>* obj, Integral op) noexcept;
 
 template <class Integral>
   Integral atomic_fetch_add_explicit(volatile atomic<Integral>* obj, Integral op,
                               memory_order m) noexcept;
 template <class Integral>
   Integral atomic_fetch_add_explicit(atomic<Integral>* obj, Integral op,
                               memory_order m) noexcept;
 template <class Integral>
   Integral atomic_fetch_sub(volatile atomic<Integral>* obj, Integral op) noexcept;
 
 template <class Integral>
   Integral atomic_fetch_sub(atomic<Integral>* obj, Integral op) noexcept;
 
 template <class Integral>
   Integral atomic_fetch_sub_explicit(volatile atomic<Integral>* obj, Integral op,
                                      memory_order m) noexcept;
 
 template <class Integral>
   Integral atomic_fetch_sub_explicit(atomic<Integral>* obj, Integral op,
                                      memory_order m) noexcept;
 
 template <class Integral>
   Integral atomic_fetch_and(volatile atomic<Integral>* obj, Integral op) noexcept;
 
 template <class Integral>
   Integral atomic_fetch_and(atomic<Integral>* obj, Integral op) noexcept;
 
 template <class Integral>
   Integral atomic_fetch_and_explicit(volatile atomic<Integral>* obj, Integral op,
                                      memory_order m) noexcept;
 
 template <class Integral>
   Integral atomic_fetch_and_explicit(atomic<Integral>* obj, Integral op,
                                      memory_order m) noexcept;
 
 template <class Integral>
   Integral atomic_fetch_or(volatile atomic<Integral>* obj, Integral op) noexcept;
 
 template <class Integral>
   Integral atomic_fetch_or(atomic<Integral>* obj, Integral op) noexcept;
 
 template <class Integral>
   Integral atomic_fetch_or_explicit(volatile atomic<Integral>* obj, Integral op,
                              memory_order m) noexcept;
 
 template <class Integral>
   Integral atomic_fetch_or_explicit(atomic<Integral>* obj, Integral op,
                              memory_order m) noexcept;
 
 template <class Integral>
   Integral atomic_fetch_xor(volatile atomic<Integral>* obj, Integral op) noexcept;
 
 template <class Integral>
   Integral atomic_fetch_xor(atomic<Integral>* obj, Integral op) noexcept;
 
 template <class Integral>
   Integral atomic_fetch_xor_explicit(volatile atomic<Integral>* obj, Integral op,
                                      memory_order m) noexcept;
 
 template <class Integral>
   Integral atomic_fetch_xor_explicit(atomic<Integral>* obj, Integral op,
                                      memory_order m) noexcept;
 
 template <class T>
   T* atomic_fetch_add(volatile atomic<T*>* obj, ptrdiff_t op) noexcept;
 
 template <class T>
   T* atomic_fetch_add(atomic<T*>* obj, ptrdiff_t op) noexcept;
 
 template <class T>
   T* atomic_fetch_add_explicit(volatile atomic<T*>* obj, ptrdiff_t op,
                                memory_order m) noexcept;
 
 template <class T>
   T* atomic_fetch_add_explicit(atomic<T*>* obj, ptrdiff_t op, memory_order m) noexcept;
 
 template <class T>
   T* atomic_fetch_sub(volatile atomic<T*>* obj, ptrdiff_t op) noexcept;
 
 template <class T>
   T* atomic_fetch_sub(atomic<T*>* obj, ptrdiff_t op) noexcept;
 
 template <class T>
   T* atomic_fetch_sub_explicit(volatile atomic<T*>* obj, ptrdiff_t op,
                                memory_order m) noexcept;
 
 template <class T>
   T* atomic_fetch_sub_explicit(atomic<T*>* obj, ptrdiff_t op, memory_order m) noexcept;
 
 // Atomics for standard typedef types
 
 typedef atomic<bool>               atomic_bool;
 typedef atomic<char>               atomic_char;
 typedef atomic<signed char>        atomic_schar;
 typedef atomic<unsigned char>      atomic_uchar;
 typedef atomic<short>              atomic_short;
 typedef atomic<unsigned short>     atomic_ushort;
 typedef atomic<int>                atomic_int;
 typedef atomic<unsigned int>       atomic_uint;
 typedef atomic<long>               atomic_long;
 typedef atomic<unsigned long>      atomic_ulong;
 typedef atomic<long long>          atomic_llong;
 typedef atomic<unsigned long long> atomic_ullong;
 typedef atomic<char16_t>           atomic_char16_t;
 typedef atomic<char32_t>           atomic_char32_t;
 typedef atomic<wchar_t>            atomic_wchar_t;
 
 typedef atomic<int_least8_t>   atomic_int_least8_t;
 typedef atomic<uint_least8_t>  atomic_uint_least8_t;
 typedef atomic<int_least16_t>  atomic_int_least16_t;
 typedef atomic<uint_least16_t> atomic_uint_least16_t;
 typedef atomic<int_least32_t>  atomic_int_least32_t;
 typedef atomic<uint_least32_t> atomic_uint_least32_t;
 typedef atomic<int_least64_t>  atomic_int_least64_t;
 typedef atomic<uint_least64_t> atomic_uint_least64_t;
 
 typedef atomic<int_fast8_t>   atomic_int_fast8_t;
 typedef atomic<uint_fast8_t>  atomic_uint_fast8_t;
 typedef atomic<int_fast16_t>  atomic_int_fast16_t;
 typedef atomic<uint_fast16_t> atomic_uint_fast16_t;
 typedef atomic<int_fast32_t>  atomic_int_fast32_t;    
 typedef atomic<uint_fast32_t> atomic_uint_fast32_t;
 typedef atomic<int_fast64_t>  atomic_int_fast64_t;
 typedef atomic<uint_fast64_t> atomic_uint_fast64_t;
 
 typedef atomic<int8_t>   atomic_int8_t;
 typedef atomic<uint8_t>  atomic_uint8_t;
 typedef atomic<int16_t>  atomic_int16_t;
 typedef atomic<uint16_t> atomic_uint16_t;
 typedef atomic<int32_t>  atomic_int32_t;
 typedef atomic<uint32_t> atomic_uint32_t;
 typedef atomic<int64_t>  atomic_int64_t;
 typedef atomic<uint64_t> atomic_uint64_t;
 
 typedef atomic<intptr_t>  atomic_intptr_t;
 typedef atomic<uintptr_t> atomic_uintptr_t;
 typedef atomic<size_t>    atomic_size_t;
 typedef atomic<ptrdiff_t> atomic_ptrdiff_t;
 typedef atomic<intmax_t>  atomic_intmax_t;
 typedef atomic<uintmax_t> atomic_uintmax_t;
 
 // flag type and operations
 
 typedef struct atomic_flag
 {
     atomic_flag() noexcept = default;
     atomic_flag(const atomic_flag&) = delete;
     atomic_flag& operator=(const atomic_flag&) = delete;
     atomic_flag& operator=(const atomic_flag&) volatile = delete;
 
     bool test(memory_order m = memory_order_seq_cst) volatile noexcept;
     bool test(memory_order m = memory_order_seq_cst) noexcept;
     bool test_and_set(memory_order m = memory_order_seq_cst) volatile noexcept;
     bool test_and_set(memory_order m = memory_order_seq_cst) noexcept;
     void clear(memory_order m = memory_order_seq_cst) volatile noexcept;
     void clear(memory_order m = memory_order_seq_cst) noexcept;
 
     void wait(bool, memory_order = memory_order::seq_cst) const volatile noexcept;
     void wait(bool, memory_order = memory_order::seq_cst) const noexcept;
     void notify_one() volatile noexcept;
     void notify_one() noexcept;
     void notify_all() volatile noexcept;
     void notify_all() noexcept;
 } atomic_flag;
 
 bool atomic_flag_test(volatile atomic_flag* obj) noexcept;
 bool atomic_flag_test(atomic_flag* obj) noexcept;
 bool atomic_flag_test_explicit(volatile atomic_flag* obj,
                                memory_order m) noexcept;
 bool atomic_flag_test_explicit(atomic_flag* obj, memory_order m) noexcept;
 bool atomic_flag_test_and_set(volatile atomic_flag* obj) noexcept;
 bool atomic_flag_test_and_set(atomic_flag* obj) noexcept;
 bool atomic_flag_test_and_set_explicit(volatile atomic_flag* obj,
                                        memory_order m) noexcept;
 bool atomic_flag_test_and_set_explicit(atomic_flag* obj, memory_order m) noexcept;
 void atomic_flag_clear(volatile atomic_flag* obj) noexcept;
 void atomic_flag_clear(atomic_flag* obj) noexcept;
 void atomic_flag_clear_explicit(volatile atomic_flag* obj, memory_order m) noexcept;
 void atomic_flag_clear_explicit(atomic_flag* obj, memory_order m) noexcept;
 
 void atomic_wait(const volatile atomic_flag* obj, T old) noexcept;
 void atomic_wait(const atomic_flag* obj, T old) noexcept;
 void atomic_wait_explicit(const volatile atomic_flag* obj, T old, memory_order m) noexcept;
 void atomic_wait_explicit(const atomic_flag* obj, T old, memory_order m) noexcept;
 void atomic_one(volatile atomic_flag* obj) noexcept;
 void atomic_one(atomic_flag* obj) noexcept;
 void atomic_all(volatile atomic_flag* obj) noexcept;
 void atomic_all(atomic_flag* obj) noexcept;
 
 // fences
 
 void atomic_thread_fence(memory_order m) noexcept;
 void atomic_signal_fence(memory_order m) noexcept;
 
 // deprecated
 
 template <class T>
   void atomic_init(volatile atomic<T>* obj, typename atomic<T>::value_type desr) noexcept;
 
 template <class T>
   void atomic_init(atomic<T>* obj, typename atomic<T>::value_type desr) noexcept;
 
 #define ATOMIC_VAR_INIT(value) see below
 
 #define ATOMIC_FLAG_INIT see below
 
 }  // std
 
 */
 
 #include <__config>
 #include <__threading_support>
 #include <cstddef>
 #include <cstdint>
 #include <cstring>
 #include <type_traits>
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 #ifdef _LIBCPP_HAS_NO_THREADS
 # error <atomic> is not supported on this single threaded system
 #endif
 #ifdef _LIBCPP_HAS_NO_ATOMIC_HEADER
 # error <atomic> is not implemented
 #endif
 #ifdef kill_dependency
 # error C++ standard library is incompatible with <stdatomic.h>
 #endif
 
 #define _LIBCPP_CHECK_STORE_MEMORY_ORDER(__m) \
   _LIBCPP_DIAGNOSE_WARNING(__m == memory_order_consume || \
                            __m == memory_order_acquire || \
                            __m == memory_order_acq_rel,   \
                         "memory order argument to atomic operation is invalid")
 
 #define _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m) \
   _LIBCPP_DIAGNOSE_WARNING(__m == memory_order_release || \
                            __m == memory_order_acq_rel,   \
                         "memory order argument to atomic operation is invalid")
 
 #define _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__m, __f) \
   _LIBCPP_DIAGNOSE_WARNING(__f == memory_order_release || \
                            __f == memory_order_acq_rel,   \
                         "memory order argument to atomic operation is invalid")
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 // Figure out what the underlying type for `memory_order` would be if it were
 // declared as an unscoped enum (accounting for -fshort-enums). Use this result
 // to pin the underlying type in C++20.
 enum __legacy_memory_order {
     __mo_relaxed,
     __mo_consume,
     __mo_acquire,
     __mo_release,
     __mo_acq_rel,
     __mo_seq_cst
 };
 
 typedef underlying_type<__legacy_memory_order>::type __memory_order_underlying_t;
 
 #if _LIBCPP_STD_VER > 17
 
 enum class memory_order : __memory_order_underlying_t {
   relaxed = __mo_relaxed,
   consume = __mo_consume,
   acquire = __mo_acquire,
   release = __mo_release,
   acq_rel = __mo_acq_rel,
   seq_cst = __mo_seq_cst
 };
 
 inline constexpr auto memory_order_relaxed = memory_order::relaxed;
 inline constexpr auto memory_order_consume = memory_order::consume;
 inline constexpr auto memory_order_acquire = memory_order::acquire;
 inline constexpr auto memory_order_release = memory_order::release;
 inline constexpr auto memory_order_acq_rel = memory_order::acq_rel;
 inline constexpr auto memory_order_seq_cst = memory_order::seq_cst;
 
 #else
 
 typedef enum memory_order {
   memory_order_relaxed = __mo_relaxed,
   memory_order_consume = __mo_consume,
   memory_order_acquire = __mo_acquire,
   memory_order_release = __mo_release,
   memory_order_acq_rel = __mo_acq_rel,
   memory_order_seq_cst = __mo_seq_cst,
 } memory_order;
 
 #endif // _LIBCPP_STD_VER > 17
 
 template <typename _Tp> _LIBCPP_INLINE_VISIBILITY
 bool __cxx_nonatomic_compare_equal(_Tp const& __lhs, _Tp const& __rhs) {
     return memcmp(&__lhs, &__rhs, sizeof(_Tp)) == 0;
 }
 
 static_assert((is_same<underlying_type<memory_order>::type, __memory_order_underlying_t>::value),
   "unexpected underlying type for std::memory_order");
 
 #if defined(_LIBCPP_HAS_GCC_ATOMIC_IMP) || \
 	defined(_LIBCPP_ATOMIC_ONLY_USE_BUILTINS)
 
 // [atomics.types.generic]p1 guarantees _Tp is trivially copyable. Because
 // the default operator= in an object is not volatile, a byte-by-byte copy
 // is required.
 template <typename _Tp, typename _Tv> _LIBCPP_INLINE_VISIBILITY
 typename enable_if<is_assignable<_Tp&, _Tv>::value>::type
 __cxx_atomic_assign_volatile(_Tp& __a_value, _Tv const& __val) {
   __a_value = __val;
 }
 template <typename _Tp, typename _Tv> _LIBCPP_INLINE_VISIBILITY
 typename enable_if<is_assignable<_Tp&, _Tv>::value>::type
 __cxx_atomic_assign_volatile(_Tp volatile& __a_value, _Tv volatile const& __val) {
   volatile char* __to = reinterpret_cast<volatile char*>(&__a_value);
   volatile char* __end = __to + sizeof(_Tp);
   volatile const char* __from = reinterpret_cast<volatile const char*>(&__val);
   while (__to != __end)
     *__to++ = *__from++;
 }
 
 #endif
 
 #if defined(_LIBCPP_HAS_GCC_ATOMIC_IMP)
 
 template <typename _Tp>
 struct __cxx_atomic_base_impl {
 
   _LIBCPP_INLINE_VISIBILITY
 #ifndef _LIBCPP_CXX03_LANG
     __cxx_atomic_base_impl() _NOEXCEPT = default;
 #else
     __cxx_atomic_base_impl() _NOEXCEPT : __a_value() {}
 #endif // _LIBCPP_CXX03_LANG
   _LIBCPP_CONSTEXPR explicit __cxx_atomic_base_impl(_Tp value) _NOEXCEPT
     : __a_value(value) {}
   _Tp __a_value;
 };
 
 _LIBCPP_INLINE_VISIBILITY inline _LIBCPP_CONSTEXPR int __to_gcc_order(memory_order __order) {
   // Avoid switch statement to make this a constexpr.
   return __order == memory_order_relaxed ? __ATOMIC_RELAXED:
          (__order == memory_order_acquire ? __ATOMIC_ACQUIRE:
           (__order == memory_order_release ? __ATOMIC_RELEASE:
            (__order == memory_order_seq_cst ? __ATOMIC_SEQ_CST:
             (__order == memory_order_acq_rel ? __ATOMIC_ACQ_REL:
               __ATOMIC_CONSUME))));
 }
 
 _LIBCPP_INLINE_VISIBILITY inline _LIBCPP_CONSTEXPR int __to_gcc_failure_order(memory_order __order) {
   // Avoid switch statement to make this a constexpr.
   return __order == memory_order_relaxed ? __ATOMIC_RELAXED:
          (__order == memory_order_acquire ? __ATOMIC_ACQUIRE:
           (__order == memory_order_release ? __ATOMIC_RELAXED:
            (__order == memory_order_seq_cst ? __ATOMIC_SEQ_CST:
             (__order == memory_order_acq_rel ? __ATOMIC_ACQUIRE:
               __ATOMIC_CONSUME))));
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 void __cxx_atomic_init(volatile __cxx_atomic_base_impl<_Tp>* __a,  _Tp __val) {
   __cxx_atomic_assign_volatile(__a->__a_value, __val);
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 void __cxx_atomic_init(__cxx_atomic_base_impl<_Tp>* __a,  _Tp __val) {
   __a->__a_value = __val;
 }
 
 _LIBCPP_INLINE_VISIBILITY inline
 void __cxx_atomic_thread_fence(memory_order __order) {
   __atomic_thread_fence(__to_gcc_order(__order));
 }
 
 _LIBCPP_INLINE_VISIBILITY inline
 void __cxx_atomic_signal_fence(memory_order __order) {
   __atomic_signal_fence(__to_gcc_order(__order));
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 void __cxx_atomic_store(volatile __cxx_atomic_base_impl<_Tp>* __a,  _Tp __val,
                         memory_order __order) {
   __atomic_store(&__a->__a_value, &__val,
                  __to_gcc_order(__order));
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 void __cxx_atomic_store(__cxx_atomic_base_impl<_Tp>* __a,  _Tp __val,
                         memory_order __order) {
   __atomic_store(&__a->__a_value, &__val,
                  __to_gcc_order(__order));
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_load(const volatile __cxx_atomic_base_impl<_Tp>* __a,
                       memory_order __order) {
   _Tp __ret;
   __atomic_load(&__a->__a_value, &__ret,
                 __to_gcc_order(__order));
   return __ret;
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_load(const __cxx_atomic_base_impl<_Tp>* __a, memory_order __order) {
   _Tp __ret;
   __atomic_load(&__a->__a_value, &__ret,
                 __to_gcc_order(__order));
   return __ret;
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_exchange(volatile __cxx_atomic_base_impl<_Tp>* __a,
                           _Tp __value, memory_order __order) {
   _Tp __ret;
   __atomic_exchange(&__a->__a_value, &__value, &__ret,
                     __to_gcc_order(__order));
   return __ret;
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_exchange(__cxx_atomic_base_impl<_Tp>* __a, _Tp __value,
                           memory_order __order) {
   _Tp __ret;
   __atomic_exchange(&__a->__a_value, &__value, &__ret,
                     __to_gcc_order(__order));
   return __ret;
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool __cxx_atomic_compare_exchange_strong(
     volatile __cxx_atomic_base_impl<_Tp>* __a, _Tp* __expected, _Tp __value,
     memory_order __success, memory_order __failure) {
   return __atomic_compare_exchange(&__a->__a_value, __expected, &__value,
                                    false,
                                    __to_gcc_order(__success),
                                    __to_gcc_failure_order(__failure));
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool __cxx_atomic_compare_exchange_strong(
     __cxx_atomic_base_impl<_Tp>* __a, _Tp* __expected, _Tp __value, memory_order __success,
     memory_order __failure) {
   return __atomic_compare_exchange(&__a->__a_value, __expected, &__value,
                                    false,
                                    __to_gcc_order(__success),
                                    __to_gcc_failure_order(__failure));
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool __cxx_atomic_compare_exchange_weak(
     volatile __cxx_atomic_base_impl<_Tp>* __a, _Tp* __expected, _Tp __value,
     memory_order __success, memory_order __failure) {
   return __atomic_compare_exchange(&__a->__a_value, __expected, &__value,
                                    true,
                                    __to_gcc_order(__success),
                                    __to_gcc_failure_order(__failure));
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool __cxx_atomic_compare_exchange_weak(
     __cxx_atomic_base_impl<_Tp>* __a, _Tp* __expected, _Tp __value, memory_order __success,
     memory_order __failure) {
   return __atomic_compare_exchange(&__a->__a_value, __expected, &__value,
                                    true,
                                    __to_gcc_order(__success),
                                    __to_gcc_failure_order(__failure));
 }
 
 template <typename _Tp>
 struct __skip_amt { enum {value = 1}; };
 
 template <typename _Tp>
 struct __skip_amt<_Tp*> { enum {value = sizeof(_Tp)}; };
 
 // FIXME: Haven't figured out what the spec says about using arrays with
 // atomic_fetch_add. Force a failure rather than creating bad behavior.
 template <typename _Tp>
 struct __skip_amt<_Tp[]> { };
 template <typename _Tp, int n>
 struct __skip_amt<_Tp[n]> { };
 
 template <typename _Tp, typename _Td>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_add(volatile __cxx_atomic_base_impl<_Tp>* __a,
                            _Td __delta, memory_order __order) {
   return __atomic_fetch_add(&__a->__a_value, __delta * __skip_amt<_Tp>::value,
                             __to_gcc_order(__order));
 }
 
 template <typename _Tp, typename _Td>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_add(__cxx_atomic_base_impl<_Tp>* __a, _Td __delta,
                            memory_order __order) {
   return __atomic_fetch_add(&__a->__a_value, __delta * __skip_amt<_Tp>::value,
                             __to_gcc_order(__order));
 }
 
 template <typename _Tp, typename _Td>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_sub(volatile __cxx_atomic_base_impl<_Tp>* __a,
                            _Td __delta, memory_order __order) {
   return __atomic_fetch_sub(&__a->__a_value, __delta * __skip_amt<_Tp>::value,
                             __to_gcc_order(__order));
 }
 
 template <typename _Tp, typename _Td>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_sub(__cxx_atomic_base_impl<_Tp>* __a, _Td __delta,
                            memory_order __order) {
   return __atomic_fetch_sub(&__a->__a_value, __delta * __skip_amt<_Tp>::value,
                             __to_gcc_order(__order));
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_and(volatile __cxx_atomic_base_impl<_Tp>* __a,
                            _Tp __pattern, memory_order __order) {
   return __atomic_fetch_and(&__a->__a_value, __pattern,
                             __to_gcc_order(__order));
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_and(__cxx_atomic_base_impl<_Tp>* __a,
                            _Tp __pattern, memory_order __order) {
   return __atomic_fetch_and(&__a->__a_value, __pattern,
                             __to_gcc_order(__order));
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_or(volatile __cxx_atomic_base_impl<_Tp>* __a,
                           _Tp __pattern, memory_order __order) {
   return __atomic_fetch_or(&__a->__a_value, __pattern,
                            __to_gcc_order(__order));
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_or(__cxx_atomic_base_impl<_Tp>* __a, _Tp __pattern,
                           memory_order __order) {
   return __atomic_fetch_or(&__a->__a_value, __pattern,
                            __to_gcc_order(__order));
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_xor(volatile __cxx_atomic_base_impl<_Tp>* __a,
                            _Tp __pattern, memory_order __order) {
   return __atomic_fetch_xor(&__a->__a_value, __pattern,
                             __to_gcc_order(__order));
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_xor(__cxx_atomic_base_impl<_Tp>* __a, _Tp __pattern,
                            memory_order __order) {
   return __atomic_fetch_xor(&__a->__a_value, __pattern,
                             __to_gcc_order(__order));
 }
 
 #define __cxx_atomic_is_lock_free(__s) __atomic_is_lock_free(__s, 0)
 
 #elif defined(_LIBCPP_HAS_C_ATOMIC_IMP)
 
 template <typename _Tp>
 struct __cxx_atomic_base_impl {
 
   _LIBCPP_INLINE_VISIBILITY
 #ifndef _LIBCPP_CXX03_LANG
     __cxx_atomic_base_impl() _NOEXCEPT = default;
 #else
     __cxx_atomic_base_impl() _NOEXCEPT : __a_value() {}
 #endif // _LIBCPP_CXX03_LANG
   _LIBCPP_CONSTEXPR explicit __cxx_atomic_base_impl(_Tp value) _NOEXCEPT
     : __a_value(value) {}
   _LIBCPP_DISABLE_EXTENSION_WARNING _Atomic(_Tp) __a_value;
 };
 
 #define __cxx_atomic_is_lock_free(__s) __c11_atomic_is_lock_free(__s)
 
 _LIBCPP_INLINE_VISIBILITY inline
 void __cxx_atomic_thread_fence(memory_order __order) _NOEXCEPT {
     __c11_atomic_thread_fence(static_cast<__memory_order_underlying_t>(__order));
 }
 
 _LIBCPP_INLINE_VISIBILITY inline
 void __cxx_atomic_signal_fence(memory_order __order) _NOEXCEPT {
     __c11_atomic_signal_fence(static_cast<__memory_order_underlying_t>(__order));
 }
 
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 void __cxx_atomic_init(__cxx_atomic_base_impl<_Tp> volatile* __a, _Tp __val) _NOEXCEPT {
     __c11_atomic_init(&__a->__a_value, __val);
 }
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 void __cxx_atomic_init(__cxx_atomic_base_impl<_Tp> * __a, _Tp __val) _NOEXCEPT {
     __c11_atomic_init(&__a->__a_value, __val);
 }
 
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 void __cxx_atomic_store(__cxx_atomic_base_impl<_Tp> volatile* __a, _Tp __val, memory_order __order) _NOEXCEPT {
     __c11_atomic_store(&__a->__a_value, __val, static_cast<__memory_order_underlying_t>(__order));
 }
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 void __cxx_atomic_store(__cxx_atomic_base_impl<_Tp> * __a, _Tp __val, memory_order __order) _NOEXCEPT {
     __c11_atomic_store(&__a->__a_value, __val, static_cast<__memory_order_underlying_t>(__order));
 }
 
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_load(__cxx_atomic_base_impl<_Tp> const volatile* __a, memory_order __order) _NOEXCEPT {
     using __ptr_type = typename remove_const<decltype(__a->__a_value)>::type*;
     return __c11_atomic_load(const_cast<__ptr_type>(&__a->__a_value), static_cast<__memory_order_underlying_t>(__order));
 }
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_load(__cxx_atomic_base_impl<_Tp> const* __a, memory_order __order) _NOEXCEPT {
     using __ptr_type = typename remove_const<decltype(__a->__a_value)>::type*;
     return __c11_atomic_load(const_cast<__ptr_type>(&__a->__a_value), static_cast<__memory_order_underlying_t>(__order));
 }
 
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_exchange(__cxx_atomic_base_impl<_Tp> volatile* __a, _Tp __value, memory_order __order) _NOEXCEPT {
     return __c11_atomic_exchange(&__a->__a_value, __value, static_cast<__memory_order_underlying_t>(__order));
 }
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_exchange(__cxx_atomic_base_impl<_Tp> * __a, _Tp __value, memory_order __order) _NOEXCEPT {
     return __c11_atomic_exchange(&__a->__a_value, __value, static_cast<__memory_order_underlying_t>(__order));
 }
 
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool __cxx_atomic_compare_exchange_strong(__cxx_atomic_base_impl<_Tp> volatile* __a, _Tp* __expected, _Tp __value, memory_order __success, memory_order __failure) _NOEXCEPT {
     return __c11_atomic_compare_exchange_strong(&__a->__a_value, __expected, __value, static_cast<__memory_order_underlying_t>(__success), static_cast<__memory_order_underlying_t>(__failure));
 }
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool __cxx_atomic_compare_exchange_strong(__cxx_atomic_base_impl<_Tp> * __a, _Tp* __expected, _Tp __value, memory_order __success, memory_order __failure) _NOEXCEPT {
     return __c11_atomic_compare_exchange_strong(&__a->__a_value, __expected, __value, static_cast<__memory_order_underlying_t>(__success), static_cast<__memory_order_underlying_t>(__failure));
 }
 
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool __cxx_atomic_compare_exchange_weak(__cxx_atomic_base_impl<_Tp> volatile* __a, _Tp* __expected, _Tp __value, memory_order __success, memory_order __failure) _NOEXCEPT {
     return __c11_atomic_compare_exchange_weak(&__a->__a_value, __expected, __value, static_cast<__memory_order_underlying_t>(__success), static_cast<__memory_order_underlying_t>(__failure));
 }
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool __cxx_atomic_compare_exchange_weak(__cxx_atomic_base_impl<_Tp> * __a, _Tp* __expected, _Tp __value, memory_order __success, memory_order __failure) _NOEXCEPT {
     return __c11_atomic_compare_exchange_weak(&__a->__a_value, __expected, __value,  static_cast<__memory_order_underlying_t>(__success), static_cast<__memory_order_underlying_t>(__failure));
 }
 
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_add(__cxx_atomic_base_impl<_Tp> volatile* __a, _Tp __delta, memory_order __order) _NOEXCEPT {
     return __c11_atomic_fetch_add(&__a->__a_value, __delta, static_cast<__memory_order_underlying_t>(__order));
 }
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_add(__cxx_atomic_base_impl<_Tp> * __a, _Tp __delta, memory_order __order) _NOEXCEPT {
     return __c11_atomic_fetch_add(&__a->__a_value, __delta, static_cast<__memory_order_underlying_t>(__order));
 }
 
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp* __cxx_atomic_fetch_add(__cxx_atomic_base_impl<_Tp*> volatile* __a, ptrdiff_t __delta, memory_order __order) _NOEXCEPT {
     return __c11_atomic_fetch_add(&__a->__a_value, __delta, static_cast<__memory_order_underlying_t>(__order));
 }
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp* __cxx_atomic_fetch_add(__cxx_atomic_base_impl<_Tp*> * __a, ptrdiff_t __delta, memory_order __order) _NOEXCEPT {
     return __c11_atomic_fetch_add(&__a->__a_value, __delta, static_cast<__memory_order_underlying_t>(__order));
 }
 
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_sub(__cxx_atomic_base_impl<_Tp> volatile* __a, _Tp __delta, memory_order __order) _NOEXCEPT {
     return __c11_atomic_fetch_sub(&__a->__a_value, __delta, static_cast<__memory_order_underlying_t>(__order));
 }
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_sub(__cxx_atomic_base_impl<_Tp> * __a, _Tp __delta, memory_order __order) _NOEXCEPT {
     return __c11_atomic_fetch_sub(&__a->__a_value, __delta, static_cast<__memory_order_underlying_t>(__order));
 }
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp* __cxx_atomic_fetch_sub(__cxx_atomic_base_impl<_Tp*> volatile* __a, ptrdiff_t __delta, memory_order __order) _NOEXCEPT {
     return __c11_atomic_fetch_sub(&__a->__a_value, __delta, static_cast<__memory_order_underlying_t>(__order));
 }
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp* __cxx_atomic_fetch_sub(__cxx_atomic_base_impl<_Tp*> * __a, ptrdiff_t __delta, memory_order __order) _NOEXCEPT {
     return __c11_atomic_fetch_sub(&__a->__a_value, __delta, static_cast<__memory_order_underlying_t>(__order));
 }
 
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_and(__cxx_atomic_base_impl<_Tp> volatile* __a, _Tp __pattern, memory_order __order) _NOEXCEPT {
     return __c11_atomic_fetch_and(&__a->__a_value, __pattern, static_cast<__memory_order_underlying_t>(__order));
 }
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_and(__cxx_atomic_base_impl<_Tp> * __a, _Tp __pattern, memory_order __order) _NOEXCEPT {
     return __c11_atomic_fetch_and(&__a->__a_value, __pattern, static_cast<__memory_order_underlying_t>(__order));
 }
 
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_or(__cxx_atomic_base_impl<_Tp> volatile* __a, _Tp __pattern, memory_order __order) _NOEXCEPT {
     return __c11_atomic_fetch_or(&__a->__a_value, __pattern, static_cast<__memory_order_underlying_t>(__order));
 }
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_or(__cxx_atomic_base_impl<_Tp> * __a, _Tp __pattern, memory_order __order) _NOEXCEPT {
     return __c11_atomic_fetch_or(&__a->__a_value, __pattern, static_cast<__memory_order_underlying_t>(__order));
 }
 
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_xor(__cxx_atomic_base_impl<_Tp> volatile* __a, _Tp __pattern, memory_order __order) _NOEXCEPT {
     return __c11_atomic_fetch_xor(&__a->__a_value, __pattern, static_cast<__memory_order_underlying_t>(__order));
 }
 template<class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_xor(__cxx_atomic_base_impl<_Tp> * __a, _Tp __pattern, memory_order __order) _NOEXCEPT {
     return __c11_atomic_fetch_xor(&__a->__a_value, __pattern, static_cast<__memory_order_underlying_t>(__order));
 }
 
 #endif // _LIBCPP_HAS_GCC_ATOMIC_IMP, _LIBCPP_HAS_C_ATOMIC_IMP
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp kill_dependency(_Tp __y) _NOEXCEPT
 {
     return __y;
 }
 
 #if defined(__CLANG_ATOMIC_BOOL_LOCK_FREE)
 # define ATOMIC_BOOL_LOCK_FREE      __CLANG_ATOMIC_BOOL_LOCK_FREE
 # define ATOMIC_CHAR_LOCK_FREE      __CLANG_ATOMIC_CHAR_LOCK_FREE
 # define ATOMIC_CHAR16_T_LOCK_FREE  __CLANG_ATOMIC_CHAR16_T_LOCK_FREE
 # define ATOMIC_CHAR32_T_LOCK_FREE  __CLANG_ATOMIC_CHAR32_T_LOCK_FREE
 # define ATOMIC_WCHAR_T_LOCK_FREE   __CLANG_ATOMIC_WCHAR_T_LOCK_FREE
 # define ATOMIC_SHORT_LOCK_FREE     __CLANG_ATOMIC_SHORT_LOCK_FREE
 # define ATOMIC_INT_LOCK_FREE       __CLANG_ATOMIC_INT_LOCK_FREE
 # define ATOMIC_LONG_LOCK_FREE      __CLANG_ATOMIC_LONG_LOCK_FREE
 # define ATOMIC_LLONG_LOCK_FREE     __CLANG_ATOMIC_LLONG_LOCK_FREE
 # define ATOMIC_POINTER_LOCK_FREE   __CLANG_ATOMIC_POINTER_LOCK_FREE
 #elif defined(__GCC_ATOMIC_BOOL_LOCK_FREE)
 # define ATOMIC_BOOL_LOCK_FREE      __GCC_ATOMIC_BOOL_LOCK_FREE
 # define ATOMIC_CHAR_LOCK_FREE      __GCC_ATOMIC_CHAR_LOCK_FREE
 # define ATOMIC_CHAR16_T_LOCK_FREE  __GCC_ATOMIC_CHAR16_T_LOCK_FREE
 # define ATOMIC_CHAR32_T_LOCK_FREE  __GCC_ATOMIC_CHAR32_T_LOCK_FREE
 # define ATOMIC_WCHAR_T_LOCK_FREE   __GCC_ATOMIC_WCHAR_T_LOCK_FREE
 # define ATOMIC_SHORT_LOCK_FREE     __GCC_ATOMIC_SHORT_LOCK_FREE
 # define ATOMIC_INT_LOCK_FREE       __GCC_ATOMIC_INT_LOCK_FREE
 # define ATOMIC_LONG_LOCK_FREE      __GCC_ATOMIC_LONG_LOCK_FREE
 # define ATOMIC_LLONG_LOCK_FREE     __GCC_ATOMIC_LLONG_LOCK_FREE
 # define ATOMIC_POINTER_LOCK_FREE   __GCC_ATOMIC_POINTER_LOCK_FREE
 #endif
 
 #ifdef _LIBCPP_ATOMIC_ONLY_USE_BUILTINS
 
 template<typename _Tp>
 struct __cxx_atomic_lock_impl {
 
   _LIBCPP_INLINE_VISIBILITY
   __cxx_atomic_lock_impl() _NOEXCEPT
     : __a_value(), __a_lock(0) {}
   _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR explicit
   __cxx_atomic_lock_impl(_Tp value) _NOEXCEPT
     : __a_value(value), __a_lock(0) {}
 
   _Tp __a_value;
   mutable __cxx_atomic_base_impl<_LIBCPP_ATOMIC_FLAG_TYPE> __a_lock;
 
   _LIBCPP_INLINE_VISIBILITY void __lock() const volatile {
     while(1 == __cxx_atomic_exchange(&__a_lock, _LIBCPP_ATOMIC_FLAG_TYPE(true), memory_order_acquire))
         /*spin*/;
   }
   _LIBCPP_INLINE_VISIBILITY void __lock() const {
     while(1 == __cxx_atomic_exchange(&__a_lock, _LIBCPP_ATOMIC_FLAG_TYPE(true), memory_order_acquire))
         /*spin*/;
   }
   _LIBCPP_INLINE_VISIBILITY void __unlock() const volatile {
     __cxx_atomic_store(&__a_lock, _LIBCPP_ATOMIC_FLAG_TYPE(false), memory_order_release);
   }
   _LIBCPP_INLINE_VISIBILITY void __unlock() const {
     __cxx_atomic_store(&__a_lock, _LIBCPP_ATOMIC_FLAG_TYPE(false), memory_order_release);
   }
   _LIBCPP_INLINE_VISIBILITY _Tp __read() const volatile {
     __lock();
     _Tp __old;
     __cxx_atomic_assign_volatile(__old, __a_value);
     __unlock();
     return __old;
   }
   _LIBCPP_INLINE_VISIBILITY _Tp __read() const {
     __lock();
     _Tp __old = __a_value;
     __unlock();
     return __old;
   }
 };
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 void __cxx_atomic_init(volatile __cxx_atomic_lock_impl<_Tp>* __a,  _Tp __val) {
   __cxx_atomic_assign_volatile(__a->__a_value, __val);
 }
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 void __cxx_atomic_init(__cxx_atomic_lock_impl<_Tp>* __a,  _Tp __val) {
   __a->__a_value = __val;
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 void __cxx_atomic_store(volatile __cxx_atomic_lock_impl<_Tp>* __a,  _Tp __val, memory_order) {
   __a->__lock();
   __cxx_atomic_assign_volatile(__a->__a_value, __val);
   __a->__unlock();
 }
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 void __cxx_atomic_store(__cxx_atomic_lock_impl<_Tp>* __a,  _Tp __val, memory_order) {
   __a->__lock();
   __a->__a_value = __val;
   __a->__unlock();
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_load(const volatile __cxx_atomic_lock_impl<_Tp>* __a, memory_order) {
   return __a->__read();
 }
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_load(const __cxx_atomic_lock_impl<_Tp>* __a, memory_order) {
   return __a->__read();
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_exchange(volatile __cxx_atomic_lock_impl<_Tp>* __a, _Tp __value, memory_order) {
   __a->__lock();
   _Tp __old;
   __cxx_atomic_assign_volatile(__old, __a->__a_value);
   __cxx_atomic_assign_volatile(__a->__a_value, __value);
   __a->__unlock();
   return __old;
 }
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_exchange(__cxx_atomic_lock_impl<_Tp>* __a, _Tp __value, memory_order) {
   __a->__lock();
   _Tp __old = __a->__a_value;
   __a->__a_value = __value;
   __a->__unlock();
   return __old;
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool __cxx_atomic_compare_exchange_strong(volatile __cxx_atomic_lock_impl<_Tp>* __a,
                                           _Tp* __expected, _Tp __value, memory_order, memory_order) {
   __a->__lock();
   _Tp __temp;
   __cxx_atomic_assign_volatile(__temp, __a->__a_value);
   bool __ret = __temp == *__expected;
   if(__ret)
     __cxx_atomic_assign_volatile(__a->__a_value, __value);
   else
     __cxx_atomic_assign_volatile(*__expected, __a->__a_value);
   __a->__unlock();
   return __ret;
 }
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool __cxx_atomic_compare_exchange_strong(__cxx_atomic_lock_impl<_Tp>* __a,
                                           _Tp* __expected, _Tp __value, memory_order, memory_order) {
   __a->__lock();
   bool __ret = __a->__a_value == *__expected;
   if(__ret)
     __a->__a_value = __value;
   else
     *__expected = __a->__a_value;
   __a->__unlock();
   return __ret;
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool __cxx_atomic_compare_exchange_weak(volatile __cxx_atomic_lock_impl<_Tp>* __a,
                                         _Tp* __expected, _Tp __value, memory_order, memory_order) {
   __a->__lock();
   _Tp __temp;
   __cxx_atomic_assign_volatile(__temp, __a->__a_value);
   bool __ret = __temp == *__expected;
   if(__ret)
     __cxx_atomic_assign_volatile(__a->__a_value, __value);
   else
     __cxx_atomic_assign_volatile(*__expected, __a->__a_value);
   __a->__unlock();
   return __ret;
 }
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool __cxx_atomic_compare_exchange_weak(__cxx_atomic_lock_impl<_Tp>* __a,
                                         _Tp* __expected, _Tp __value, memory_order, memory_order) {
   __a->__lock();
   bool __ret = __a->__a_value == *__expected;
   if(__ret)
     __a->__a_value = __value;
   else
     *__expected = __a->__a_value;
   __a->__unlock();
   return __ret;
 }
 
 template <typename _Tp, typename _Td>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_add(volatile __cxx_atomic_lock_impl<_Tp>* __a,
                            _Td __delta, memory_order) {
   __a->__lock();
   _Tp __old;
   __cxx_atomic_assign_volatile(__old, __a->__a_value);
   __cxx_atomic_assign_volatile(__a->__a_value, _Tp(__old + __delta));
   __a->__unlock();
   return __old;
 }
 template <typename _Tp, typename _Td>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_add(__cxx_atomic_lock_impl<_Tp>* __a,
                            _Td __delta, memory_order) {
   __a->__lock();
   _Tp __old = __a->__a_value;
   __a->__a_value += __delta;
   __a->__unlock();
   return __old;
 }
 
 template <typename _Tp, typename _Td>
 _LIBCPP_INLINE_VISIBILITY
 _Tp* __cxx_atomic_fetch_add(volatile __cxx_atomic_lock_impl<_Tp*>* __a,
                            ptrdiff_t __delta, memory_order) {
   __a->__lock();
   _Tp* __old;
   __cxx_atomic_assign_volatile(__old, __a->__a_value);
   __cxx_atomic_assign_volatile(__a->__a_value, __old + __delta);
   __a->__unlock();
   return __old;
 }
 template <typename _Tp, typename _Td>
 _LIBCPP_INLINE_VISIBILITY
 _Tp* __cxx_atomic_fetch_add(__cxx_atomic_lock_impl<_Tp*>* __a,
                            ptrdiff_t __delta, memory_order) {
   __a->__lock();
   _Tp* __old = __a->__a_value;
   __a->__a_value += __delta;
   __a->__unlock();
   return __old;
 }
 
 template <typename _Tp, typename _Td>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_sub(volatile __cxx_atomic_lock_impl<_Tp>* __a,
                            _Td __delta, memory_order) {
   __a->__lock();
   _Tp __old;
   __cxx_atomic_assign_volatile(__old, __a->__a_value);
   __cxx_atomic_assign_volatile(__a->__a_value, _Tp(__old - __delta));
   __a->__unlock();
   return __old;
 }
 template <typename _Tp, typename _Td>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_sub(__cxx_atomic_lock_impl<_Tp>* __a,
                            _Td __delta, memory_order) {
   __a->__lock();
   _Tp __old = __a->__a_value;
   __a->__a_value -= __delta;
   __a->__unlock();
   return __old;
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_and(volatile __cxx_atomic_lock_impl<_Tp>* __a,
                            _Tp __pattern, memory_order) {
   __a->__lock();
   _Tp __old;
   __cxx_atomic_assign_volatile(__old, __a->__a_value);
   __cxx_atomic_assign_volatile(__a->__a_value, _Tp(__old & __pattern));
   __a->__unlock();
   return __old;
 }
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_and(__cxx_atomic_lock_impl<_Tp>* __a,
                            _Tp __pattern, memory_order) {
   __a->__lock();
   _Tp __old = __a->__a_value;
   __a->__a_value &= __pattern;
   __a->__unlock();
   return __old;
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_or(volatile __cxx_atomic_lock_impl<_Tp>* __a,
                           _Tp __pattern, memory_order) {
   __a->__lock();
   _Tp __old;
   __cxx_atomic_assign_volatile(__old, __a->__a_value);
   __cxx_atomic_assign_volatile(__a->__a_value, _Tp(__old | __pattern));
   __a->__unlock();
   return __old;
 }
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_or(__cxx_atomic_lock_impl<_Tp>* __a,
                           _Tp __pattern, memory_order) {
   __a->__lock();
   _Tp __old = __a->__a_value;
   __a->__a_value |= __pattern;
   __a->__unlock();
   return __old;
 }
 
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_xor(volatile __cxx_atomic_lock_impl<_Tp>* __a,
                            _Tp __pattern, memory_order) {
   __a->__lock();
   _Tp __old;
   __cxx_atomic_assign_volatile(__old, __a->__a_value);
   __cxx_atomic_assign_volatile(__a->__a_value, _Tp(__old ^ __pattern));
   __a->__unlock();
   return __old;
 }
 template <typename _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp __cxx_atomic_fetch_xor(__cxx_atomic_lock_impl<_Tp>* __a,
                            _Tp __pattern, memory_order) {
   __a->__lock();
   _Tp __old = __a->__a_value;
   __a->__a_value ^= __pattern;
   __a->__unlock();
   return __old;
 }
 
 #ifdef __cpp_lib_atomic_is_always_lock_free
 
 template<typename _Tp> struct __cxx_is_always_lock_free {
     enum { __value = __atomic_always_lock_free(sizeof(_Tp), 0) }; };
 
 #else
 
 template<typename _Tp> struct __cxx_is_always_lock_free { enum { __value = false }; };
 // Implementations must match the C ATOMIC_*_LOCK_FREE macro values.
 template<> struct __cxx_is_always_lock_free<bool> { enum { __value = 2 == ATOMIC_BOOL_LOCK_FREE }; };
 template<> struct __cxx_is_always_lock_free<char> { enum { __value = 2 == ATOMIC_CHAR_LOCK_FREE }; };
 template<> struct __cxx_is_always_lock_free<signed char> { enum { __value = 2 == ATOMIC_CHAR_LOCK_FREE }; };
 template<> struct __cxx_is_always_lock_free<unsigned char> { enum { __value = 2 == ATOMIC_CHAR_LOCK_FREE }; };
 template<> struct __cxx_is_always_lock_free<char16_t> { enum { __value = 2 == ATOMIC_CHAR16_T_LOCK_FREE }; };
 template<> struct __cxx_is_always_lock_free<char32_t> { enum { __value = 2 == ATOMIC_CHAR32_T_LOCK_FREE }; };
 template<> struct __cxx_is_always_lock_free<wchar_t> { enum { __value = 2 == ATOMIC_WCHAR_T_LOCK_FREE }; };
 template<> struct __cxx_is_always_lock_free<short> { enum { __value = 2 == ATOMIC_SHORT_LOCK_FREE }; };
 template<> struct __cxx_is_always_lock_free<unsigned short> { enum { __value = 2 == ATOMIC_SHORT_LOCK_FREE }; };
 template<> struct __cxx_is_always_lock_free<int> { enum { __value = 2 == ATOMIC_INT_LOCK_FREE }; };
 template<> struct __cxx_is_always_lock_free<unsigned int> { enum { __value = 2 == ATOMIC_INT_LOCK_FREE }; };
 template<> struct __cxx_is_always_lock_free<long> { enum { __value = 2 == ATOMIC_LONG_LOCK_FREE }; };
 template<> struct __cxx_is_always_lock_free<unsigned long> { enum { __value = 2 == ATOMIC_LONG_LOCK_FREE }; };
 template<> struct __cxx_is_always_lock_free<long long> { enum { __value = 2 == ATOMIC_LLONG_LOCK_FREE }; };
 template<> struct __cxx_is_always_lock_free<unsigned long long> { enum { __value = 2 == ATOMIC_LLONG_LOCK_FREE }; };
 template<typename _Tp> struct __cxx_is_always_lock_free<_Tp*> { enum { __value = 2 == ATOMIC_POINTER_LOCK_FREE }; };
 template<> struct __cxx_is_always_lock_free<std::nullptr_t> { enum { __value = 2 == ATOMIC_POINTER_LOCK_FREE }; };
 
 #endif //__cpp_lib_atomic_is_always_lock_free
 
 template <typename _Tp,
           typename _Base = typename conditional<__cxx_is_always_lock_free<_Tp>::__value,
                                                 __cxx_atomic_base_impl<_Tp>,
                                                 __cxx_atomic_lock_impl<_Tp> >::type>
 #else
 template <typename _Tp,
           typename _Base = __cxx_atomic_base_impl<_Tp> >
 #endif //_LIBCPP_ATOMIC_ONLY_USE_BUILTINS
 struct __cxx_atomic_impl : public _Base {
 
 #if _GNUC_VER >= 501
     static_assert(is_trivially_copyable<_Tp>::value,
       "std::atomic<Tp> requires that 'Tp' be a trivially copyable type");
 #endif
 
   _LIBCPP_INLINE_VISIBILITY __cxx_atomic_impl() _NOEXCEPT _LIBCPP_DEFAULT
   _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR explicit __cxx_atomic_impl(_Tp value) _NOEXCEPT
     : _Base(value) {}
 };
 
-#ifdef __linux__
+#if defined(__linux__) || (defined(__FreeBSD__) && defined(__mips__))
     using __cxx_contention_t = int32_t;
 #else
     using __cxx_contention_t = int64_t;
-#endif //__linux__
+#endif
 
 #if _LIBCPP_STD_VER >= 11
 
 using __cxx_atomic_contention_t = __cxx_atomic_impl<__cxx_contention_t>;
 
 #ifndef _LIBCPP_HAS_NO_PLATFORM_WAIT
 
 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI void __cxx_atomic_notify_one(void const volatile*);
 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI void __cxx_atomic_notify_all(void const volatile*);
 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI __cxx_contention_t __libcpp_atomic_monitor(void const volatile*);
 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI void __libcpp_atomic_wait(void const volatile*, __cxx_contention_t);
 
 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI void __cxx_atomic_notify_one(__cxx_atomic_contention_t const volatile*);
 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI void __cxx_atomic_notify_all(__cxx_atomic_contention_t const volatile*);
 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI __cxx_contention_t __libcpp_atomic_monitor(__cxx_atomic_contention_t const volatile*);
 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI void __libcpp_atomic_wait(__cxx_atomic_contention_t const volatile*, __cxx_contention_t);
 
 template <class _Atp, class _Fn>
 struct __libcpp_atomic_wait_backoff_impl {
     _Atp* __a;
     _Fn __test_fn;
     _LIBCPP_AVAILABILITY_SYNC
     _LIBCPP_INLINE_VISIBILITY bool operator()(chrono::nanoseconds __elapsed) const
     {
         if(__elapsed > chrono::microseconds(64))
         {
             auto const __monitor = __libcpp_atomic_monitor(__a);
             if(__test_fn())
                 return true;
             __libcpp_atomic_wait(__a, __monitor);
         }
         else if(__elapsed > chrono::microseconds(4))
             __libcpp_thread_yield();
         else
             ; // poll
         return false;
     }
 };
 
 template <class _Atp, class _Fn>
 _LIBCPP_AVAILABILITY_SYNC
 _LIBCPP_INLINE_VISIBILITY bool __cxx_atomic_wait(_Atp* __a, _Fn && __test_fn)
 {
     __libcpp_atomic_wait_backoff_impl<_Atp, typename decay<_Fn>::type> __backoff_fn = {__a, __test_fn};
     return __libcpp_thread_poll_with_backoff(__test_fn, __backoff_fn);
 }
 
 #else // _LIBCPP_HAS_NO_PLATFORM_WAIT
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY void __cxx_atomic_notify_all(__cxx_atomic_impl<_Tp> const volatile*) { }
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY void __cxx_atomic_notify_one(__cxx_atomic_impl<_Tp> const volatile*) { }
 template <class _Atp, class _Fn>
 _LIBCPP_INLINE_VISIBILITY bool __cxx_atomic_wait(_Atp*, _Fn && __test_fn)
 {
     return __libcpp_thread_poll_with_backoff(__test_fn, __libcpp_timed_backoff_policy());
 }
 
 #endif // _LIBCPP_HAS_NO_PLATFORM_WAIT
 
 template <class _Atp, class _Tp>
 struct __cxx_atomic_wait_test_fn_impl {
     _Atp* __a;
     _Tp __val;
     memory_order __order;
     _LIBCPP_INLINE_VISIBILITY bool operator()() const
     {
         return !__cxx_nonatomic_compare_equal(__cxx_atomic_load(__a, __order), __val);
     }
 };
 
 template <class _Atp, class _Tp>
 _LIBCPP_AVAILABILITY_SYNC
 _LIBCPP_INLINE_VISIBILITY bool __cxx_atomic_wait(_Atp* __a, _Tp const __val, memory_order __order)
 {
     __cxx_atomic_wait_test_fn_impl<_Atp, _Tp> __test_fn = {__a, __val, __order};
     return __cxx_atomic_wait(__a, __test_fn);
 }
 
 #endif //_LIBCPP_STD_VER >= 11
 
 // general atomic<T>
 
 template <class _Tp, bool = is_integral<_Tp>::value && !is_same<_Tp, bool>::value>
 struct __atomic_base  // false
 {
     mutable __cxx_atomic_impl<_Tp> __a_;
 
 #if defined(__cpp_lib_atomic_is_always_lock_free)
   static _LIBCPP_CONSTEXPR bool is_always_lock_free = __atomic_always_lock_free(sizeof(__a_), 0);
 #endif
 
     _LIBCPP_INLINE_VISIBILITY
     bool is_lock_free() const volatile _NOEXCEPT
         {return __cxx_atomic_is_lock_free(sizeof(_Tp));}
     _LIBCPP_INLINE_VISIBILITY
     bool is_lock_free() const _NOEXCEPT
         {return static_cast<__atomic_base const volatile*>(this)->is_lock_free();}
     _LIBCPP_INLINE_VISIBILITY
     void store(_Tp __d, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
       _LIBCPP_CHECK_STORE_MEMORY_ORDER(__m)
         {__cxx_atomic_store(&__a_, __d, __m);}
     _LIBCPP_INLINE_VISIBILITY
     void store(_Tp __d, memory_order __m = memory_order_seq_cst) _NOEXCEPT
       _LIBCPP_CHECK_STORE_MEMORY_ORDER(__m)
         {__cxx_atomic_store(&__a_, __d, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp load(memory_order __m = memory_order_seq_cst) const volatile _NOEXCEPT
       _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m)
         {return __cxx_atomic_load(&__a_, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp load(memory_order __m = memory_order_seq_cst) const _NOEXCEPT
       _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m)
         {return __cxx_atomic_load(&__a_, __m);}
     _LIBCPP_INLINE_VISIBILITY
     operator _Tp() const volatile _NOEXCEPT {return load();}
     _LIBCPP_INLINE_VISIBILITY
     operator _Tp() const _NOEXCEPT          {return load();}
     _LIBCPP_INLINE_VISIBILITY
     _Tp exchange(_Tp __d, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
         {return __cxx_atomic_exchange(&__a_, __d, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp exchange(_Tp __d, memory_order __m = memory_order_seq_cst) _NOEXCEPT
         {return __cxx_atomic_exchange(&__a_, __d, __m);}
     _LIBCPP_INLINE_VISIBILITY
     bool compare_exchange_weak(_Tp& __e, _Tp __d,
                                memory_order __s, memory_order __f) volatile _NOEXCEPT
       _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f)
         {return __cxx_atomic_compare_exchange_weak(&__a_, &__e, __d, __s, __f);}
     _LIBCPP_INLINE_VISIBILITY
     bool compare_exchange_weak(_Tp& __e, _Tp __d,
                                memory_order __s, memory_order __f) _NOEXCEPT
       _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f)
         {return __cxx_atomic_compare_exchange_weak(&__a_, &__e, __d, __s, __f);}
     _LIBCPP_INLINE_VISIBILITY
     bool compare_exchange_strong(_Tp& __e, _Tp __d,
                                  memory_order __s, memory_order __f) volatile _NOEXCEPT
       _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f)
         {return __cxx_atomic_compare_exchange_strong(&__a_, &__e, __d, __s, __f);}
     _LIBCPP_INLINE_VISIBILITY
     bool compare_exchange_strong(_Tp& __e, _Tp __d,
                                  memory_order __s, memory_order __f) _NOEXCEPT
       _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f)
         {return __cxx_atomic_compare_exchange_strong(&__a_, &__e, __d, __s, __f);}
     _LIBCPP_INLINE_VISIBILITY
     bool compare_exchange_weak(_Tp& __e, _Tp __d,
                               memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
         {return __cxx_atomic_compare_exchange_weak(&__a_, &__e, __d, __m, __m);}
     _LIBCPP_INLINE_VISIBILITY
     bool compare_exchange_weak(_Tp& __e, _Tp __d,
                                memory_order __m = memory_order_seq_cst) _NOEXCEPT
         {return __cxx_atomic_compare_exchange_weak(&__a_, &__e, __d, __m, __m);}
     _LIBCPP_INLINE_VISIBILITY
     bool compare_exchange_strong(_Tp& __e, _Tp __d,
                               memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
         {return __cxx_atomic_compare_exchange_strong(&__a_, &__e, __d, __m, __m);}
     _LIBCPP_INLINE_VISIBILITY
     bool compare_exchange_strong(_Tp& __e, _Tp __d,
                                  memory_order __m = memory_order_seq_cst) _NOEXCEPT
         {return __cxx_atomic_compare_exchange_strong(&__a_, &__e, __d, __m, __m);}
 
     _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY void wait(_Tp __v, memory_order __m = memory_order_seq_cst) const volatile _NOEXCEPT
         {__cxx_atomic_wait(&__a_, __v, __m);}
     _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY void wait(_Tp __v, memory_order __m = memory_order_seq_cst) const _NOEXCEPT
         {__cxx_atomic_wait(&__a_, __v, __m);}
     _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY void notify_one() volatile _NOEXCEPT
         {__cxx_atomic_notify_one(&__a_);}
     _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY void notify_one() _NOEXCEPT
         {__cxx_atomic_notify_one(&__a_);}
     _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY void notify_all() volatile _NOEXCEPT
         {__cxx_atomic_notify_all(&__a_);}
     _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY void notify_all() _NOEXCEPT
         {__cxx_atomic_notify_all(&__a_);}
 
     _LIBCPP_INLINE_VISIBILITY
     __atomic_base() _NOEXCEPT _LIBCPP_DEFAULT
 
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     __atomic_base(_Tp __d) _NOEXCEPT : __a_(__d) {}
 
 #ifndef _LIBCPP_CXX03_LANG
     __atomic_base(const __atomic_base&) = delete;
     __atomic_base& operator=(const __atomic_base&) = delete;
     __atomic_base& operator=(const __atomic_base&) volatile = delete;
 #else
 private:
     _LIBCPP_INLINE_VISIBILITY
     __atomic_base(const __atomic_base&);
     _LIBCPP_INLINE_VISIBILITY
     __atomic_base& operator=(const __atomic_base&);
     _LIBCPP_INLINE_VISIBILITY
     __atomic_base& operator=(const __atomic_base&) volatile;
 #endif
 };
 
 #if defined(__cpp_lib_atomic_is_always_lock_free)
 template <class _Tp, bool __b>
 _LIBCPP_CONSTEXPR bool __atomic_base<_Tp, __b>::is_always_lock_free;
 #endif
 
 // atomic<Integral>
 
 template <class _Tp>
 struct __atomic_base<_Tp, true>
     : public __atomic_base<_Tp, false>
 {
     typedef __atomic_base<_Tp, false> __base;
     _LIBCPP_INLINE_VISIBILITY
     __atomic_base() _NOEXCEPT _LIBCPP_DEFAULT
     _LIBCPP_INLINE_VISIBILITY
     _LIBCPP_CONSTEXPR __atomic_base(_Tp __d) _NOEXCEPT : __base(__d) {}
 
     _LIBCPP_INLINE_VISIBILITY
     _Tp fetch_add(_Tp __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
         {return __cxx_atomic_fetch_add(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp fetch_add(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT
         {return __cxx_atomic_fetch_add(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp fetch_sub(_Tp __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
         {return __cxx_atomic_fetch_sub(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp fetch_sub(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT
         {return __cxx_atomic_fetch_sub(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp fetch_and(_Tp __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
         {return __cxx_atomic_fetch_and(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp fetch_and(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT
         {return __cxx_atomic_fetch_and(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp fetch_or(_Tp __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
         {return __cxx_atomic_fetch_or(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp fetch_or(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT
         {return __cxx_atomic_fetch_or(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp fetch_xor(_Tp __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
         {return __cxx_atomic_fetch_xor(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp fetch_xor(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT
         {return __cxx_atomic_fetch_xor(&this->__a_, __op, __m);}
 
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator++(int) volatile _NOEXCEPT      {return fetch_add(_Tp(1));}
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator++(int) _NOEXCEPT               {return fetch_add(_Tp(1));}
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator--(int) volatile _NOEXCEPT      {return fetch_sub(_Tp(1));}
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator--(int) _NOEXCEPT               {return fetch_sub(_Tp(1));}
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator++() volatile _NOEXCEPT         {return fetch_add(_Tp(1)) + _Tp(1);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator++() _NOEXCEPT                  {return fetch_add(_Tp(1)) + _Tp(1);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator--() volatile _NOEXCEPT         {return fetch_sub(_Tp(1)) - _Tp(1);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator--() _NOEXCEPT                  {return fetch_sub(_Tp(1)) - _Tp(1);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator+=(_Tp __op) volatile _NOEXCEPT {return fetch_add(__op) + __op;}
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator+=(_Tp __op) _NOEXCEPT          {return fetch_add(__op) + __op;}
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator-=(_Tp __op) volatile _NOEXCEPT {return fetch_sub(__op) - __op;}
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator-=(_Tp __op) _NOEXCEPT          {return fetch_sub(__op) - __op;}
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator&=(_Tp __op) volatile _NOEXCEPT {return fetch_and(__op) & __op;}
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator&=(_Tp __op) _NOEXCEPT          {return fetch_and(__op) & __op;}
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator|=(_Tp __op) volatile _NOEXCEPT {return fetch_or(__op) | __op;}
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator|=(_Tp __op) _NOEXCEPT          {return fetch_or(__op) | __op;}
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator^=(_Tp __op) volatile _NOEXCEPT {return fetch_xor(__op) ^ __op;}
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator^=(_Tp __op) _NOEXCEPT          {return fetch_xor(__op) ^ __op;}
 };
 
 // atomic<T>
 
 template <class _Tp>
 struct atomic
     : public __atomic_base<_Tp>
 {
     typedef __atomic_base<_Tp> __base;
     typedef _Tp value_type;
     _LIBCPP_INLINE_VISIBILITY
     atomic() _NOEXCEPT _LIBCPP_DEFAULT
     _LIBCPP_INLINE_VISIBILITY
     _LIBCPP_CONSTEXPR atomic(_Tp __d) _NOEXCEPT : __base(__d) {}
 
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator=(_Tp __d) volatile _NOEXCEPT
         {__base::store(__d); return __d;}
     _LIBCPP_INLINE_VISIBILITY
     _Tp operator=(_Tp __d) _NOEXCEPT
         {__base::store(__d); return __d;}
 };
 
 // atomic<T*>
 
 template <class _Tp>
 struct atomic<_Tp*>
     : public __atomic_base<_Tp*>
 {
     typedef __atomic_base<_Tp*> __base;
     typedef _Tp* value_type;
     _LIBCPP_INLINE_VISIBILITY
     atomic() _NOEXCEPT _LIBCPP_DEFAULT
     _LIBCPP_INLINE_VISIBILITY
     _LIBCPP_CONSTEXPR atomic(_Tp* __d) _NOEXCEPT : __base(__d) {}
 
     _LIBCPP_INLINE_VISIBILITY
     _Tp* operator=(_Tp* __d) volatile _NOEXCEPT
         {__base::store(__d); return __d;}
     _LIBCPP_INLINE_VISIBILITY
     _Tp* operator=(_Tp* __d) _NOEXCEPT
         {__base::store(__d); return __d;}
 
     _LIBCPP_INLINE_VISIBILITY
     _Tp* fetch_add(ptrdiff_t __op, memory_order __m = memory_order_seq_cst)
                                                                         volatile _NOEXCEPT
         {return __cxx_atomic_fetch_add(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp* fetch_add(ptrdiff_t __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT
         {return __cxx_atomic_fetch_add(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp* fetch_sub(ptrdiff_t __op, memory_order __m = memory_order_seq_cst)
                                                                         volatile _NOEXCEPT
         {return __cxx_atomic_fetch_sub(&this->__a_, __op, __m);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp* fetch_sub(ptrdiff_t __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT
         {return __cxx_atomic_fetch_sub(&this->__a_, __op, __m);}
 
     _LIBCPP_INLINE_VISIBILITY
     _Tp* operator++(int) volatile _NOEXCEPT            {return fetch_add(1);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp* operator++(int) _NOEXCEPT                     {return fetch_add(1);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp* operator--(int) volatile _NOEXCEPT            {return fetch_sub(1);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp* operator--(int) _NOEXCEPT                     {return fetch_sub(1);}
     _LIBCPP_INLINE_VISIBILITY
     _Tp* operator++() volatile _NOEXCEPT               {return fetch_add(1) + 1;}
     _LIBCPP_INLINE_VISIBILITY
     _Tp* operator++() _NOEXCEPT                        {return fetch_add(1) + 1;}
     _LIBCPP_INLINE_VISIBILITY
     _Tp* operator--() volatile _NOEXCEPT               {return fetch_sub(1) - 1;}
     _LIBCPP_INLINE_VISIBILITY
     _Tp* operator--() _NOEXCEPT                        {return fetch_sub(1) - 1;}
     _LIBCPP_INLINE_VISIBILITY
     _Tp* operator+=(ptrdiff_t __op) volatile _NOEXCEPT {return fetch_add(__op) + __op;}
     _LIBCPP_INLINE_VISIBILITY
     _Tp* operator+=(ptrdiff_t __op) _NOEXCEPT          {return fetch_add(__op) + __op;}
     _LIBCPP_INLINE_VISIBILITY
     _Tp* operator-=(ptrdiff_t __op) volatile _NOEXCEPT {return fetch_sub(__op) - __op;}
     _LIBCPP_INLINE_VISIBILITY
     _Tp* operator-=(ptrdiff_t __op) _NOEXCEPT          {return fetch_sub(__op) - __op;}
 };
 
 // atomic_is_lock_free
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool
 atomic_is_lock_free(const volatile atomic<_Tp>* __o) _NOEXCEPT
 {
     return __o->is_lock_free();
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool
 atomic_is_lock_free(const atomic<_Tp>* __o) _NOEXCEPT
 {
     return __o->is_lock_free();
 }
 
 // atomic_init
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 void
 atomic_init(volatile atomic<_Tp>* __o, _Tp __d) _NOEXCEPT
 {
     __cxx_atomic_init(&__o->__a_, __d);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 void
 atomic_init(atomic<_Tp>* __o, _Tp __d) _NOEXCEPT
 {
     __cxx_atomic_init(&__o->__a_, __d);
 }
 
 // atomic_store
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 void
 atomic_store(volatile atomic<_Tp>* __o, _Tp __d) _NOEXCEPT
 {
     __o->store(__d);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 void
 atomic_store(atomic<_Tp>* __o, _Tp __d) _NOEXCEPT
 {
     __o->store(__d);
 }
 
 // atomic_store_explicit
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 void
 atomic_store_explicit(volatile atomic<_Tp>* __o, _Tp __d, memory_order __m) _NOEXCEPT
   _LIBCPP_CHECK_STORE_MEMORY_ORDER(__m)
 {
     __o->store(__d, __m);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 void
 atomic_store_explicit(atomic<_Tp>* __o, _Tp __d, memory_order __m) _NOEXCEPT
   _LIBCPP_CHECK_STORE_MEMORY_ORDER(__m)
 {
     __o->store(__d, __m);
 }
 
 // atomic_load
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp
 atomic_load(const volatile atomic<_Tp>* __o) _NOEXCEPT
 {
     return __o->load();
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp
 atomic_load(const atomic<_Tp>* __o) _NOEXCEPT
 {
     return __o->load();
 }
 
 // atomic_load_explicit
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp
 atomic_load_explicit(const volatile atomic<_Tp>* __o, memory_order __m) _NOEXCEPT
   _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m)
 {
     return __o->load(__m);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp
 atomic_load_explicit(const atomic<_Tp>* __o, memory_order __m) _NOEXCEPT
   _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m)
 {
     return __o->load(__m);
 }
 
 // atomic_exchange
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp
 atomic_exchange(volatile atomic<_Tp>* __o, _Tp __d) _NOEXCEPT
 {
     return __o->exchange(__d);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp
 atomic_exchange(atomic<_Tp>* __o, _Tp __d) _NOEXCEPT
 {
     return __o->exchange(__d);
 }
 
 // atomic_exchange_explicit
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp
 atomic_exchange_explicit(volatile atomic<_Tp>* __o, _Tp __d, memory_order __m) _NOEXCEPT
 {
     return __o->exchange(__d, __m);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp
 atomic_exchange_explicit(atomic<_Tp>* __o, _Tp __d, memory_order __m) _NOEXCEPT
 {
     return __o->exchange(__d, __m);
 }
 
 // atomic_compare_exchange_weak
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool
 atomic_compare_exchange_weak(volatile atomic<_Tp>* __o, _Tp* __e, _Tp __d) _NOEXCEPT
 {
     return __o->compare_exchange_weak(*__e, __d);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool
 atomic_compare_exchange_weak(atomic<_Tp>* __o, _Tp* __e, _Tp __d) _NOEXCEPT
 {
     return __o->compare_exchange_weak(*__e, __d);
 }
 
 // atomic_compare_exchange_strong
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool
 atomic_compare_exchange_strong(volatile atomic<_Tp>* __o, _Tp* __e, _Tp __d) _NOEXCEPT
 {
     return __o->compare_exchange_strong(*__e, __d);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool
 atomic_compare_exchange_strong(atomic<_Tp>* __o, _Tp* __e, _Tp __d) _NOEXCEPT
 {
     return __o->compare_exchange_strong(*__e, __d);
 }
 
 // atomic_compare_exchange_weak_explicit
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool
 atomic_compare_exchange_weak_explicit(volatile atomic<_Tp>* __o, _Tp* __e,
                                       _Tp __d,
                                       memory_order __s, memory_order __f) _NOEXCEPT
   _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f)
 {
     return __o->compare_exchange_weak(*__e, __d, __s, __f);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool
 atomic_compare_exchange_weak_explicit(atomic<_Tp>* __o, _Tp* __e, _Tp __d,
                                       memory_order __s, memory_order __f) _NOEXCEPT
   _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f)
 {
     return __o->compare_exchange_weak(*__e, __d, __s, __f);
 }
 
 // atomic_compare_exchange_strong_explicit
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool
 atomic_compare_exchange_strong_explicit(volatile atomic<_Tp>* __o,
                                         _Tp* __e, _Tp __d,
                                         memory_order __s, memory_order __f) _NOEXCEPT
   _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f)
 {
     return __o->compare_exchange_strong(*__e, __d, __s, __f);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 bool
 atomic_compare_exchange_strong_explicit(atomic<_Tp>* __o, _Tp* __e,
                                         _Tp __d,
                                         memory_order __s, memory_order __f) _NOEXCEPT
   _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f)
 {
     return __o->compare_exchange_strong(*__e, __d, __s, __f);
 }
 
 // atomic_wait
 
 template <class _Tp>
 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY
 void atomic_wait(const volatile atomic<_Tp>* __o,
                  typename atomic<_Tp>::value_type __v) _NOEXCEPT
 {
     return __o->wait(__v);
 }
 
 template <class _Tp>
 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY
 void atomic_wait(const atomic<_Tp>* __o,
                  typename atomic<_Tp>::value_type __v) _NOEXCEPT
 {
     return __o->wait(__v);
 }
 
 // atomic_wait_explicit
 
 template <class _Tp>
 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY
 void atomic_wait_explicit(const volatile atomic<_Tp>* __o,
                           typename atomic<_Tp>::value_type __v,
                           memory_order __m) _NOEXCEPT
   _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m)
 {
     return __o->wait(__v, __m);
 }
 
 template <class _Tp>
 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY
 void atomic_wait_explicit(const atomic<_Tp>* __o,
                           typename atomic<_Tp>::value_type __v,
                           memory_order __m) _NOEXCEPT
   _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m)
 {
     return __o->wait(__v, __m);
 }
 
 // atomic_notify_one
 
 template <class _Tp>
 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY
 void atomic_notify_one(volatile atomic<_Tp>* __o) _NOEXCEPT
 {
     __o->notify_one();
 }
 template <class _Tp>
 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY
 void atomic_notify_one(atomic<_Tp>* __o) _NOEXCEPT
 {
     __o->notify_one();
 }
 
 // atomic_notify_one
 
 template <class _Tp>
 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY
 void atomic_notify_all(volatile atomic<_Tp>* __o) _NOEXCEPT
 {
     __o->notify_all();
 }
 template <class _Tp>
 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY
 void atomic_notify_all(atomic<_Tp>* __o) _NOEXCEPT
 {
     __o->notify_all();
 }
 
 // atomic_fetch_add
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
     is_integral<_Tp>::value && !is_same<_Tp, bool>::value,
     _Tp
 >::type
 atomic_fetch_add(volatile atomic<_Tp>* __o, _Tp __op) _NOEXCEPT
 {
     return __o->fetch_add(__op);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
     is_integral<_Tp>::value && !is_same<_Tp, bool>::value,
     _Tp
 >::type
 atomic_fetch_add(atomic<_Tp>* __o, _Tp __op) _NOEXCEPT
 {
     return __o->fetch_add(__op);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp*
 atomic_fetch_add(volatile atomic<_Tp*>* __o, ptrdiff_t __op) _NOEXCEPT
 {
     return __o->fetch_add(__op);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp*
 atomic_fetch_add(atomic<_Tp*>* __o, ptrdiff_t __op) _NOEXCEPT
 {
     return __o->fetch_add(__op);
 }
 
 // atomic_fetch_add_explicit
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
     is_integral<_Tp>::value && !is_same<_Tp, bool>::value,
     _Tp
 >::type
 atomic_fetch_add_explicit(volatile atomic<_Tp>* __o, _Tp __op, memory_order __m) _NOEXCEPT
 {
     return __o->fetch_add(__op, __m);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
     is_integral<_Tp>::value && !is_same<_Tp, bool>::value,
     _Tp
 >::type
 atomic_fetch_add_explicit(atomic<_Tp>* __o, _Tp __op, memory_order __m) _NOEXCEPT
 {
     return __o->fetch_add(__op, __m);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp*
 atomic_fetch_add_explicit(volatile atomic<_Tp*>* __o, ptrdiff_t __op,
                           memory_order __m) _NOEXCEPT
 {
     return __o->fetch_add(__op, __m);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp*
 atomic_fetch_add_explicit(atomic<_Tp*>* __o, ptrdiff_t __op, memory_order __m) _NOEXCEPT
 {
     return __o->fetch_add(__op, __m);
 }
 
 // atomic_fetch_sub
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
     is_integral<_Tp>::value && !is_same<_Tp, bool>::value,
     _Tp
 >::type
 atomic_fetch_sub(volatile atomic<_Tp>* __o, _Tp __op) _NOEXCEPT
 {
     return __o->fetch_sub(__op);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
     is_integral<_Tp>::value && !is_same<_Tp, bool>::value,
     _Tp
 >::type
 atomic_fetch_sub(atomic<_Tp>* __o, _Tp __op) _NOEXCEPT
 {
     return __o->fetch_sub(__op);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp*
 atomic_fetch_sub(volatile atomic<_Tp*>* __o, ptrdiff_t __op) _NOEXCEPT
 {
     return __o->fetch_sub(__op);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp*
 atomic_fetch_sub(atomic<_Tp*>* __o, ptrdiff_t __op) _NOEXCEPT
 {
     return __o->fetch_sub(__op);
 }
 
 // atomic_fetch_sub_explicit
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
     is_integral<_Tp>::value && !is_same<_Tp, bool>::value,
     _Tp
 >::type
 atomic_fetch_sub_explicit(volatile atomic<_Tp>* __o, _Tp __op, memory_order __m) _NOEXCEPT
 {
     return __o->fetch_sub(__op, __m);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
     is_integral<_Tp>::value && !is_same<_Tp, bool>::value,
     _Tp
 >::type
 atomic_fetch_sub_explicit(atomic<_Tp>* __o, _Tp __op, memory_order __m) _NOEXCEPT
 {
     return __o->fetch_sub(__op, __m);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp*
 atomic_fetch_sub_explicit(volatile atomic<_Tp*>* __o, ptrdiff_t __op,
                           memory_order __m) _NOEXCEPT
 {
     return __o->fetch_sub(__op, __m);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 _Tp*
 atomic_fetch_sub_explicit(atomic<_Tp*>* __o, ptrdiff_t __op, memory_order __m) _NOEXCEPT
 {
     return __o->fetch_sub(__op, __m);
 }
 
 // atomic_fetch_and
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
     is_integral<_Tp>::value && !is_same<_Tp, bool>::value,
     _Tp
 >::type
 atomic_fetch_and(volatile atomic<_Tp>* __o, _Tp __op) _NOEXCEPT
 {
     return __o->fetch_and(__op);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
     is_integral<_Tp>::value && !is_same<_Tp, bool>::value,
     _Tp
 >::type
 atomic_fetch_and(atomic<_Tp>* __o, _Tp __op) _NOEXCEPT
 {
     return __o->fetch_and(__op);
 }
 
 // atomic_fetch_and_explicit
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
     is_integral<_Tp>::value && !is_same<_Tp, bool>::value,
     _Tp
 >::type
 atomic_fetch_and_explicit(volatile atomic<_Tp>* __o, _Tp __op, memory_order __m) _NOEXCEPT
 {
     return __o->fetch_and(__op, __m);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
     is_integral<_Tp>::value && !is_same<_Tp, bool>::value,
     _Tp
 >::type
 atomic_fetch_and_explicit(atomic<_Tp>* __o, _Tp __op, memory_order __m) _NOEXCEPT
 {
     return __o->fetch_and(__op, __m);
 }
 
 // atomic_fetch_or
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
     is_integral<_Tp>::value && !is_same<_Tp, bool>::value,
     _Tp
 >::type
 atomic_fetch_or(volatile atomic<_Tp>* __o, _Tp __op) _NOEXCEPT
 {
     return __o->fetch_or(__op);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
     is_integral<_Tp>::value && !is_same<_Tp, bool>::value,
     _Tp
 >::type
 atomic_fetch_or(atomic<_Tp>* __o, _Tp __op) _NOEXCEPT
 {
     return __o->fetch_or(__op);
 }
 
 // atomic_fetch_or_explicit
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
     is_integral<_Tp>::value && !is_same<_Tp, bool>::value,
     _Tp
 >::type
 atomic_fetch_or_explicit(volatile atomic<_Tp>* __o, _Tp __op, memory_order __m) _NOEXCEPT
 {
     return __o->fetch_or(__op, __m);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
     is_integral<_Tp>::value && !is_same<_Tp, bool>::value,
     _Tp
 >::type
 atomic_fetch_or_explicit(atomic<_Tp>* __o, _Tp __op, memory_order __m) _NOEXCEPT
 {
     return __o->fetch_or(__op, __m);
 }
 
 // atomic_fetch_xor
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
     is_integral<_Tp>::value && !is_same<_Tp, bool>::value,
     _Tp
 >::type
 atomic_fetch_xor(volatile atomic<_Tp>* __o, _Tp __op) _NOEXCEPT
 {
     return __o->fetch_xor(__op);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
     is_integral<_Tp>::value && !is_same<_Tp, bool>::value,
     _Tp
 >::type
 atomic_fetch_xor(atomic<_Tp>* __o, _Tp __op) _NOEXCEPT
 {
     return __o->fetch_xor(__op);
 }
 
 // atomic_fetch_xor_explicit
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
     is_integral<_Tp>::value && !is_same<_Tp, bool>::value,
     _Tp
 >::type
 atomic_fetch_xor_explicit(volatile atomic<_Tp>* __o, _Tp __op, memory_order __m) _NOEXCEPT
 {
     return __o->fetch_xor(__op, __m);
 }
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
     is_integral<_Tp>::value && !is_same<_Tp, bool>::value,
     _Tp
 >::type
 atomic_fetch_xor_explicit(atomic<_Tp>* __o, _Tp __op, memory_order __m) _NOEXCEPT
 {
     return __o->fetch_xor(__op, __m);
 }
 
 // flag type and operations
 
 typedef struct atomic_flag
 {
     __cxx_atomic_impl<_LIBCPP_ATOMIC_FLAG_TYPE> __a_;
 
     _LIBCPP_INLINE_VISIBILITY
     bool test(memory_order __m = memory_order_seq_cst) const volatile _NOEXCEPT
         {return _LIBCPP_ATOMIC_FLAG_TYPE(true) == __cxx_atomic_load(&__a_, __m);}
     _LIBCPP_INLINE_VISIBILITY
     bool test(memory_order __m = memory_order_seq_cst) const _NOEXCEPT
         {return _LIBCPP_ATOMIC_FLAG_TYPE(true) == __cxx_atomic_load(&__a_, __m);}
 
     _LIBCPP_INLINE_VISIBILITY
     bool test_and_set(memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
         {return __cxx_atomic_exchange(&__a_, _LIBCPP_ATOMIC_FLAG_TYPE(true), __m);}
     _LIBCPP_INLINE_VISIBILITY
     bool test_and_set(memory_order __m = memory_order_seq_cst) _NOEXCEPT
         {return __cxx_atomic_exchange(&__a_, _LIBCPP_ATOMIC_FLAG_TYPE(true), __m);}
     _LIBCPP_INLINE_VISIBILITY
     void clear(memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
         {__cxx_atomic_store(&__a_, _LIBCPP_ATOMIC_FLAG_TYPE(false), __m);}
     _LIBCPP_INLINE_VISIBILITY
     void clear(memory_order __m = memory_order_seq_cst) _NOEXCEPT
         {__cxx_atomic_store(&__a_, _LIBCPP_ATOMIC_FLAG_TYPE(false), __m);}
 
     _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY
     void wait(bool __v, memory_order __m = memory_order_seq_cst) const volatile _NOEXCEPT
         {__cxx_atomic_wait(&__a_, _LIBCPP_ATOMIC_FLAG_TYPE(__v), __m);}
     _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY
     void wait(bool __v, memory_order __m = memory_order_seq_cst) const _NOEXCEPT
         {__cxx_atomic_wait(&__a_, _LIBCPP_ATOMIC_FLAG_TYPE(__v), __m);}
     _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY
     void notify_one() volatile _NOEXCEPT
         {__cxx_atomic_notify_one(&__a_);}
     _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY
     void notify_one() _NOEXCEPT
         {__cxx_atomic_notify_one(&__a_);}
     _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY
     void notify_all() volatile _NOEXCEPT
         {__cxx_atomic_notify_all(&__a_);}
     _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY
     void notify_all() _NOEXCEPT
         {__cxx_atomic_notify_all(&__a_);}
 
     _LIBCPP_INLINE_VISIBILITY
     atomic_flag() _NOEXCEPT _LIBCPP_DEFAULT
 
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     atomic_flag(bool __b) _NOEXCEPT : __a_(__b) {} // EXTENSION
 
 #ifndef _LIBCPP_CXX03_LANG
     atomic_flag(const atomic_flag&) = delete;
     atomic_flag& operator=(const atomic_flag&) = delete;
     atomic_flag& operator=(const atomic_flag&) volatile = delete;
 #else
 private:
     _LIBCPP_INLINE_VISIBILITY
     atomic_flag(const atomic_flag&);
     _LIBCPP_INLINE_VISIBILITY
     atomic_flag& operator=(const atomic_flag&);
     _LIBCPP_INLINE_VISIBILITY
     atomic_flag& operator=(const atomic_flag&) volatile;
 #endif
 } atomic_flag;
 
 
 inline _LIBCPP_INLINE_VISIBILITY
 bool
 atomic_flag_test(const volatile atomic_flag* __o) _NOEXCEPT
 {
     return __o->test();
 }
 
 inline _LIBCPP_INLINE_VISIBILITY
 bool
 atomic_flag_test(const atomic_flag* __o) _NOEXCEPT
 {
     return __o->test();
 }
 
 inline _LIBCPP_INLINE_VISIBILITY
 bool
 atomic_flag_test_explicit(const volatile atomic_flag* __o, memory_order __m) _NOEXCEPT
 {
     return __o->test(__m);
 }
 
 inline _LIBCPP_INLINE_VISIBILITY
 bool
 atomic_flag_test_explicit(const atomic_flag* __o, memory_order __m) _NOEXCEPT
 {
     return __o->test(__m);
 }
 
 inline _LIBCPP_INLINE_VISIBILITY
 bool
 atomic_flag_test_and_set(volatile atomic_flag* __o) _NOEXCEPT
 {
     return __o->test_and_set();
 }
 
 inline _LIBCPP_INLINE_VISIBILITY
 bool
 atomic_flag_test_and_set(atomic_flag* __o) _NOEXCEPT
 {
     return __o->test_and_set();
 }
 
 inline _LIBCPP_INLINE_VISIBILITY
 bool
 atomic_flag_test_and_set_explicit(volatile atomic_flag* __o, memory_order __m) _NOEXCEPT
 {
     return __o->test_and_set(__m);
 }
 
 inline _LIBCPP_INLINE_VISIBILITY
 bool
 atomic_flag_test_and_set_explicit(atomic_flag* __o, memory_order __m) _NOEXCEPT
 {
     return __o->test_and_set(__m);
 }
 
 inline _LIBCPP_INLINE_VISIBILITY
 void
 atomic_flag_clear(volatile atomic_flag* __o) _NOEXCEPT
 {
     __o->clear();
 }
 
 inline _LIBCPP_INLINE_VISIBILITY
 void
 atomic_flag_clear(atomic_flag* __o) _NOEXCEPT
 {
     __o->clear();
 }
 
 inline _LIBCPP_INLINE_VISIBILITY
 void
 atomic_flag_clear_explicit(volatile atomic_flag* __o, memory_order __m) _NOEXCEPT
 {
     __o->clear(__m);
 }
 
 inline _LIBCPP_INLINE_VISIBILITY
 void
 atomic_flag_clear_explicit(atomic_flag* __o, memory_order __m) _NOEXCEPT
 {
     __o->clear(__m);
 }
 
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_AVAILABILITY_SYNC
 void
 atomic_flag_wait(const volatile atomic_flag* __o, bool __v) _NOEXCEPT
 {
     __o->wait(__v);
 }
 
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_AVAILABILITY_SYNC
 void
 atomic_flag_wait(const atomic_flag* __o, bool __v) _NOEXCEPT
 {
     __o->wait(__v);
 }
 
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_AVAILABILITY_SYNC
 void
 atomic_flag_wait_explicit(const volatile atomic_flag* __o,
                           bool __v, memory_order __m) _NOEXCEPT
 {
     __o->wait(__v, __m);
 }
 
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_AVAILABILITY_SYNC
 void
 atomic_flag_wait_explicit(const atomic_flag* __o,
                           bool __v, memory_order __m) _NOEXCEPT
 {
     __o->wait(__v, __m);
 }
 
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_AVAILABILITY_SYNC
 void
 atomic_flag_notify_one(volatile atomic_flag* __o) _NOEXCEPT
 {
     __o->notify_one();
 }
 
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_AVAILABILITY_SYNC
 void
 atomic_flag_notify_one(atomic_flag* __o) _NOEXCEPT
 {
     __o->notify_one();
 }
 
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_AVAILABILITY_SYNC
 void
 atomic_flag_notify_all(volatile atomic_flag* __o) _NOEXCEPT
 {
     __o->notify_all();
 }
 
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_AVAILABILITY_SYNC
 void
 atomic_flag_notify_all(atomic_flag* __o) _NOEXCEPT
 {
     __o->notify_all();
 }
 
 // fences
 
 inline _LIBCPP_INLINE_VISIBILITY
 void
 atomic_thread_fence(memory_order __m) _NOEXCEPT
 {
     __cxx_atomic_thread_fence(__m);
 }
 
 inline _LIBCPP_INLINE_VISIBILITY
 void
 atomic_signal_fence(memory_order __m) _NOEXCEPT
 {
     __cxx_atomic_signal_fence(__m);
 }
 
 // Atomics for standard typedef types
 
 typedef atomic<bool>               atomic_bool;
 typedef atomic<char>               atomic_char;
 typedef atomic<signed char>        atomic_schar;
 typedef atomic<unsigned char>      atomic_uchar;
 typedef atomic<short>              atomic_short;
 typedef atomic<unsigned short>     atomic_ushort;
 typedef atomic<int>                atomic_int;
 typedef atomic<unsigned int>       atomic_uint;
 typedef atomic<long>               atomic_long;
 typedef atomic<unsigned long>      atomic_ulong;
 typedef atomic<long long>          atomic_llong;
 typedef atomic<unsigned long long> atomic_ullong;
 typedef atomic<char16_t>           atomic_char16_t;
 typedef atomic<char32_t>           atomic_char32_t;
 typedef atomic<wchar_t>            atomic_wchar_t;
 
 typedef atomic<int_least8_t>   atomic_int_least8_t;
 typedef atomic<uint_least8_t>  atomic_uint_least8_t;
 typedef atomic<int_least16_t>  atomic_int_least16_t;
 typedef atomic<uint_least16_t> atomic_uint_least16_t;
 typedef atomic<int_least32_t>  atomic_int_least32_t;
 typedef atomic<uint_least32_t> atomic_uint_least32_t;
 typedef atomic<int_least64_t>  atomic_int_least64_t;
 typedef atomic<uint_least64_t> atomic_uint_least64_t;
 
 typedef atomic<int_fast8_t>   atomic_int_fast8_t;
 typedef atomic<uint_fast8_t>  atomic_uint_fast8_t;
 typedef atomic<int_fast16_t>  atomic_int_fast16_t;
 typedef atomic<uint_fast16_t> atomic_uint_fast16_t;
 typedef atomic<int_fast32_t>  atomic_int_fast32_t;
 typedef atomic<uint_fast32_t> atomic_uint_fast32_t;
 typedef atomic<int_fast64_t>  atomic_int_fast64_t;
 typedef atomic<uint_fast64_t> atomic_uint_fast64_t;
 
 typedef atomic< int8_t>  atomic_int8_t;
 typedef atomic<uint8_t>  atomic_uint8_t;
 typedef atomic< int16_t> atomic_int16_t;
 typedef atomic<uint16_t> atomic_uint16_t;
 typedef atomic< int32_t> atomic_int32_t;
 typedef atomic<uint32_t> atomic_uint32_t;
 typedef atomic< int64_t> atomic_int64_t;
 typedef atomic<uint64_t> atomic_uint64_t;
 
 typedef atomic<intptr_t>  atomic_intptr_t;
 typedef atomic<uintptr_t> atomic_uintptr_t;
 typedef atomic<size_t>    atomic_size_t;
 typedef atomic<ptrdiff_t> atomic_ptrdiff_t;
 typedef atomic<intmax_t>  atomic_intmax_t;
 typedef atomic<uintmax_t> atomic_uintmax_t;
 
 // atomic_*_lock_free : prefer the contention type most highly, then the largest lock-free type
 
 #ifdef __cpp_lib_atomic_is_always_lock_free
 # define _LIBCPP_CONTENTION_LOCK_FREE __atomic_always_lock_free(sizeof(__cxx_contention_t), 0)
 #else
 # define _LIBCPP_CONTENTION_LOCK_FREE false
 #endif
 
 #if ATOMIC_LLONG_LOCK_FREE == 2
 typedef conditional<_LIBCPP_CONTENTION_LOCK_FREE, __cxx_contention_t, long long>::type          __libcpp_signed_lock_free;
 typedef conditional<_LIBCPP_CONTENTION_LOCK_FREE, __cxx_contention_t, unsigned long long>::type __libcpp_unsigned_lock_free;
 #elif ATOMIC_INT_LOCK_FREE == 2
 typedef conditional<_LIBCPP_CONTENTION_LOCK_FREE, __cxx_contention_t, int>::type                __libcpp_signed_lock_free;
 typedef conditional<_LIBCPP_CONTENTION_LOCK_FREE, __cxx_contention_t, unsigned int>::type       __libcpp_unsigned_lock_free;
 #elif ATOMIC_SHORT_LOCK_FREE == 2
 typedef conditional<_LIBCPP_CONTENTION_LOCK_FREE, __cxx_contention_t, short>::type              __libcpp_signed_lock_free;
 typedef conditional<_LIBCPP_CONTENTION_LOCK_FREE, __cxx_contention_t, unsigned short>::type     __libcpp_unsigned_lock_free;
 #elif ATOMIC_CHAR_LOCK_FREE == 2
 typedef conditional<_LIBCPP_CONTENTION_LOCK_FREE, __cxx_contention_t, char>::type               __libcpp_signed_lock_free;
 typedef conditional<_LIBCPP_CONTENTION_LOCK_FREE, __cxx_contention_t, unsigned char>::type      __libcpp_unsigned_lock_free;
 #else
     // No signed/unsigned lock-free types
 #endif
 
 typedef atomic<__libcpp_signed_lock_free> atomic_signed_lock_free;
 typedef atomic<__libcpp_unsigned_lock_free> atomic_unsigned_lock_free;
 
 #define ATOMIC_FLAG_INIT {false}
 #define ATOMIC_VAR_INIT(__v) {__v}
 
 _LIBCPP_END_NAMESPACE_STD
 
 #endif  // _LIBCPP_ATOMIC