+ template<typename _Tp>
+ struct atomic<_Tp*>;
+
+ /* The target's "set" value for test-and-set may not be exactly 1. */
+#if __GCC_ATOMIC_TEST_AND_SET_TRUEVAL == 1
+ typedef bool __atomic_flag_data_type;
+#else
+ typedef unsigned char __atomic_flag_data_type;
+#endif
+
+ /**
+ * @brief Base type for atomic_flag.
+ *
+ * Base type is POD with data, allowing atomic_flag to derive from
+ * it and meet the standard layout type requirement. In addition to
+ * compatibilty with a C interface, this allows different
+ * implementations of atomic_flag to use the same atomic operation
+ * functions, via a standard conversion to the __atomic_flag_base
+ * argument.
+ */
+ _GLIBCXX_BEGIN_EXTERN_C
+
+ struct __atomic_flag_base
+ {
+ __atomic_flag_data_type _M_i;
+ };
+
+ _GLIBCXX_END_EXTERN_C
+
+#define ATOMIC_FLAG_INIT { 0 }
+
+ /// atomic_flag
+ struct atomic_flag : public __atomic_flag_base
+ {
+ atomic_flag() noexcept = default;
+ ~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;
+
+ // Conversion to ATOMIC_FLAG_INIT.
+ constexpr atomic_flag(bool __i) noexcept
+ : __atomic_flag_base{ _S_init(__i) }
+ { }
+
+ bool
+ test_and_set(memory_order __m = memory_order_seq_cst) noexcept
+ {
+ return __atomic_test_and_set (&_M_i, __m);
+ }
+
+ bool
+ test_and_set(memory_order __m = memory_order_seq_cst) volatile noexcept
+ {
+ return __atomic_test_and_set (&_M_i, __m);
+ }
+
+ void
+ clear(memory_order __m = memory_order_seq_cst) noexcept
+ {
+ __glibcxx_assert(__m != memory_order_consume);
+ __glibcxx_assert(__m != memory_order_acquire);
+ __glibcxx_assert(__m != memory_order_acq_rel);
+
+ __atomic_clear (&_M_i, __m);
+ }
+
+ void
+ clear(memory_order __m = memory_order_seq_cst) volatile noexcept
+ {
+ __glibcxx_assert(__m != memory_order_consume);
+ __glibcxx_assert(__m != memory_order_acquire);
+ __glibcxx_assert(__m != memory_order_acq_rel);
+
+ __atomic_clear (&_M_i, __m);
+ }
+
+ private:
+ static constexpr __atomic_flag_data_type
+ _S_init(bool __i)
+ { return __i ? __GCC_ATOMIC_TEST_AND_SET_TRUEVAL : 0; }
+ };
+
+
+ /// Base class for atomic integrals.
+ //
+ // For each of the integral types, define atomic_[integral type] struct
+ //
+ // atomic_bool bool
+ // atomic_char char
+ // atomic_schar signed char
+ // atomic_uchar unsigned char
+ // atomic_short short
+ // atomic_ushort unsigned short
+ // atomic_int int
+ // atomic_uint unsigned int
+ // atomic_long long
+ // atomic_ulong unsigned long
+ // atomic_llong long long
+ // atomic_ullong unsigned long long
+ // atomic_char16_t char16_t
+ // atomic_char32_t char32_t
+ // atomic_wchar_t wchar_t
+ //
+ // NB: Assuming _ITp is an integral scalar type that is 1, 2, 4, or
+ // 8 bytes, since that is what GCC built-in functions for atomic
+ // memory access expect.
+ template<typename _ITp>
+ struct __atomic_base
+ {
+ private:
+ typedef _ITp __int_type;
+
+ __int_type _M_i;
+
+ public:
+ __atomic_base() noexcept = default;
+ ~__atomic_base() noexcept = default;
+ __atomic_base(const __atomic_base&) = delete;
+ __atomic_base& operator=(const __atomic_base&) = delete;
+ __atomic_base& operator=(const __atomic_base&) volatile = delete;
+
+ // Requires __int_type convertible to _M_i.
+ constexpr __atomic_base(__int_type __i) noexcept : _M_i (__i) { }
+
+ operator __int_type() const noexcept
+ { return load(); }
+
+ operator __int_type() const volatile noexcept
+ { return load(); }
+
+ __int_type
+ operator=(__int_type __i) noexcept
+ {
+ store(__i);
+ return __i;
+ }
+
+ __int_type
+ operator=(__int_type __i) volatile noexcept
+ {
+ store(__i);
+ return __i;
+ }
+
+ __int_type
+ operator++(int) noexcept
+ { return fetch_add(1); }
+
+ __int_type
+ operator++(int) volatile noexcept
+ { return fetch_add(1); }
+
+ __int_type
+ operator--(int) noexcept
+ { return fetch_sub(1); }
+
+ __int_type
+ operator--(int) volatile noexcept
+ { return fetch_sub(1); }
+
+ __int_type
+ operator++() noexcept
+ { return __atomic_add_fetch(&_M_i, 1, memory_order_seq_cst); }
+
+ __int_type
+ operator++() volatile noexcept
+ { return __atomic_add_fetch(&_M_i, 1, memory_order_seq_cst); }
+
+ __int_type
+ operator--() noexcept
+ { return __atomic_sub_fetch(&_M_i, 1, memory_order_seq_cst); }
+
+ __int_type
+ operator--() volatile noexcept
+ { return __atomic_sub_fetch(&_M_i, 1, memory_order_seq_cst); }
+
+ __int_type
+ operator+=(__int_type __i) noexcept
+ { return __atomic_add_fetch(&_M_i, __i, memory_order_seq_cst); }
+
+ __int_type
+ operator+=(__int_type __i) volatile noexcept
+ { return __atomic_add_fetch(&_M_i, __i, memory_order_seq_cst); }
+
+ __int_type
+ operator-=(__int_type __i) noexcept
+ { return __atomic_sub_fetch(&_M_i, __i, memory_order_seq_cst); }
+
+ __int_type
+ operator-=(__int_type __i) volatile noexcept
+ { return __atomic_sub_fetch(&_M_i, __i, memory_order_seq_cst); }
+
+ __int_type
+ operator&=(__int_type __i) noexcept
+ { return __atomic_and_fetch(&_M_i, __i, memory_order_seq_cst); }
+
+ __int_type
+ operator&=(__int_type __i) volatile noexcept
+ { return __atomic_and_fetch(&_M_i, __i, memory_order_seq_cst); }
+
+ __int_type
+ operator|=(__int_type __i) noexcept
+ { return __atomic_or_fetch(&_M_i, __i, memory_order_seq_cst); }
+
+ __int_type
+ operator|=(__int_type __i) volatile noexcept
+ { return __atomic_or_fetch(&_M_i, __i, memory_order_seq_cst); }
+
+ __int_type
+ operator^=(__int_type __i) noexcept
+ { return __atomic_xor_fetch(&_M_i, __i, memory_order_seq_cst); }
+
+ __int_type
+ operator^=(__int_type __i) volatile noexcept
+ { return __atomic_xor_fetch(&_M_i, __i, memory_order_seq_cst); }
+
+ bool
+ is_lock_free() const noexcept
+ { return __atomic_is_lock_free (sizeof (_M_i), &_M_i); }
+
+ bool
+ is_lock_free() const volatile noexcept
+ { return __atomic_is_lock_free (sizeof (_M_i), &_M_i); }
+
+ void
+ store(__int_type __i, memory_order __m = memory_order_seq_cst) noexcept
+ {
+ __glibcxx_assert(__m != memory_order_acquire);
+ __glibcxx_assert(__m != memory_order_acq_rel);
+ __glibcxx_assert(__m != memory_order_consume);
+
+ __atomic_store_n(&_M_i, __i, __m);
+ }
+
+ void
+ store(__int_type __i,
+ memory_order __m = memory_order_seq_cst) volatile noexcept
+ {
+ __glibcxx_assert(__m != memory_order_acquire);
+ __glibcxx_assert(__m != memory_order_acq_rel);
+ __glibcxx_assert(__m != memory_order_consume);
+
+ __atomic_store_n(&_M_i, __i, __m);
+ }
+
+ __int_type
+ load(memory_order __m = memory_order_seq_cst) const noexcept
+ {
+ __glibcxx_assert(__m != memory_order_release);
+ __glibcxx_assert(__m != memory_order_acq_rel);
+
+ return __atomic_load_n(&_M_i, __m);
+ }
+
+ __int_type
+ load(memory_order __m = memory_order_seq_cst) const volatile noexcept
+ {
+ __glibcxx_assert(__m != memory_order_release);
+ __glibcxx_assert(__m != memory_order_acq_rel);
+
+ return __atomic_load_n(&_M_i, __m);
+ }
+
+ __int_type
+ exchange(__int_type __i,
+ memory_order __m = memory_order_seq_cst) noexcept
+ {
+ return __atomic_exchange_n(&_M_i, __i, __m);
+ }
+
+
+ __int_type
+ exchange(__int_type __i,
+ memory_order __m = memory_order_seq_cst) volatile noexcept
+ {
+ return __atomic_exchange_n(&_M_i, __i, __m);
+ }
+
+ bool
+ compare_exchange_weak(__int_type& __i1, __int_type __i2,
+ memory_order __m1, memory_order __m2) noexcept
+ {
+ __glibcxx_assert(__m2 != memory_order_release);
+ __glibcxx_assert(__m2 != memory_order_acq_rel);
+ __glibcxx_assert(__m2 <= __m1);
+
+ return __atomic_compare_exchange_n(&_M_i, &__i1, __i2, 1, __m1, __m2);
+ }
+
+ bool
+ compare_exchange_weak(__int_type& __i1, __int_type __i2,
+ memory_order __m1,
+ memory_order __m2) volatile noexcept
+ {
+ __glibcxx_assert(__m2 != memory_order_release);
+ __glibcxx_assert(__m2 != memory_order_acq_rel);
+ __glibcxx_assert(__m2 <= __m1);
+
+ return __atomic_compare_exchange_n(&_M_i, &__i1, __i2, 1, __m1, __m2);
+ }
+
+ bool
+ compare_exchange_weak(__int_type& __i1, __int_type __i2,
+ memory_order __m = memory_order_seq_cst) noexcept
+ {
+ return compare_exchange_weak(__i1, __i2, __m,
+ __cmpexch_failure_order(__m));
+ }
+
+ bool
+ compare_exchange_weak(__int_type& __i1, __int_type __i2,
+ memory_order __m = memory_order_seq_cst) volatile noexcept
+ {
+ return compare_exchange_weak(__i1, __i2, __m,
+ __cmpexch_failure_order(__m));
+ }
+
+ bool
+ compare_exchange_strong(__int_type& __i1, __int_type __i2,
+ memory_order __m1, memory_order __m2) noexcept
+ {
+ __glibcxx_assert(__m2 != memory_order_release);
+ __glibcxx_assert(__m2 != memory_order_acq_rel);
+ __glibcxx_assert(__m2 <= __m1);
+
+ return __atomic_compare_exchange_n(&_M_i, &__i1, __i2, 0, __m1, __m2);
+ }
+
+ bool
+ compare_exchange_strong(__int_type& __i1, __int_type __i2,
+ memory_order __m1,
+ memory_order __m2) volatile noexcept
+ {
+ __glibcxx_assert(__m2 != memory_order_release);
+ __glibcxx_assert(__m2 != memory_order_acq_rel);
+ __glibcxx_assert(__m2 <= __m1);
+
+ return __atomic_compare_exchange_n(&_M_i, &__i1, __i2, 0, __m1, __m2);
+ }
+
+ bool
+ compare_exchange_strong(__int_type& __i1, __int_type __i2,
+ memory_order __m = memory_order_seq_cst) noexcept
+ {
+ return compare_exchange_strong(__i1, __i2, __m,
+ __cmpexch_failure_order(__m));
+ }
+
+ bool
+ compare_exchange_strong(__int_type& __i1, __int_type __i2,
+ memory_order __m = memory_order_seq_cst) volatile noexcept
+ {
+ return compare_exchange_strong(__i1, __i2, __m,
+ __cmpexch_failure_order(__m));
+ }
+
+ __int_type
+ fetch_add(__int_type __i,
+ memory_order __m = memory_order_seq_cst) noexcept
+ { return __atomic_fetch_add(&_M_i, __i, __m); }
+
+ __int_type
+ fetch_add(__int_type __i,
+ memory_order __m = memory_order_seq_cst) volatile noexcept
+ { return __atomic_fetch_add(&_M_i, __i, __m); }
+
+ __int_type
+ fetch_sub(__int_type __i,
+ memory_order __m = memory_order_seq_cst) noexcept
+ { return __atomic_fetch_sub(&_M_i, __i, __m); }
+
+ __int_type
+ fetch_sub(__int_type __i,
+ memory_order __m = memory_order_seq_cst) volatile noexcept
+ { return __atomic_fetch_sub(&_M_i, __i, __m); }
+
+ __int_type
+ fetch_and(__int_type __i,
+ memory_order __m = memory_order_seq_cst) noexcept
+ { return __atomic_fetch_and(&_M_i, __i, __m); }
+
+ __int_type
+ fetch_and(__int_type __i,
+ memory_order __m = memory_order_seq_cst) volatile noexcept
+ { return __atomic_fetch_and(&_M_i, __i, __m); }
+
+ __int_type
+ fetch_or(__int_type __i,
+ memory_order __m = memory_order_seq_cst) noexcept
+ { return __atomic_fetch_or(&_M_i, __i, __m); }
+
+ __int_type
+ fetch_or(__int_type __i,
+ memory_order __m = memory_order_seq_cst) volatile noexcept
+ { return __atomic_fetch_or(&_M_i, __i, __m); }
+
+ __int_type
+ fetch_xor(__int_type __i,
+ memory_order __m = memory_order_seq_cst) noexcept
+ { return __atomic_fetch_xor(&_M_i, __i, __m); }
+
+ __int_type
+ fetch_xor(__int_type __i,
+ memory_order __m = memory_order_seq_cst) volatile noexcept
+ { return __atomic_fetch_xor(&_M_i, __i, __m); }
+ };
+
+
+ /// Partial specialization for pointer types.
+ template<typename _PTp>
+ struct __atomic_base<_PTp*>
+ {
+ private:
+ typedef _PTp* __pointer_type;
+
+ __pointer_type _M_p;
+
+ // Factored out to facilitate explicit specialization.
+ constexpr ptrdiff_t
+ _M_type_size(ptrdiff_t __d) { return __d * sizeof(_PTp); }
+
+ constexpr ptrdiff_t
+ _M_type_size(ptrdiff_t __d) volatile { return __d * sizeof(_PTp); }
+
+ public:
+ __atomic_base() noexcept = default;
+ ~__atomic_base() noexcept = default;
+ __atomic_base(const __atomic_base&) = delete;
+ __atomic_base& operator=(const __atomic_base&) = delete;
+ __atomic_base& operator=(const __atomic_base&) volatile = delete;
+
+ // Requires __pointer_type convertible to _M_p.
+ constexpr __atomic_base(__pointer_type __p) noexcept : _M_p (__p) { }
+
+ operator __pointer_type() const noexcept
+ { return load(); }
+
+ operator __pointer_type() const volatile noexcept
+ { return load(); }
+
+ __pointer_type
+ operator=(__pointer_type __p) noexcept
+ {
+ store(__p);
+ return __p;
+ }
+
+ __pointer_type
+ operator=(__pointer_type __p) volatile noexcept
+ {
+ store(__p);
+ return __p;
+ }
+
+ __pointer_type
+ operator++(int) noexcept
+ { return fetch_add(1); }
+
+ __pointer_type
+ operator++(int) volatile noexcept
+ { return fetch_add(1); }
+
+ __pointer_type
+ operator--(int) noexcept
+ { return fetch_sub(1); }
+
+ __pointer_type
+ operator--(int) volatile noexcept
+ { return fetch_sub(1); }
+
+ __pointer_type
+ operator++() noexcept
+ { return __atomic_add_fetch(&_M_p, _M_type_size(1),
+ memory_order_seq_cst); }
+
+ __pointer_type
+ operator++() volatile noexcept
+ { return __atomic_add_fetch(&_M_p, _M_type_size(1),
+ memory_order_seq_cst); }
+
+ __pointer_type
+ operator--() noexcept
+ { return __atomic_sub_fetch(&_M_p, _M_type_size(1),
+ memory_order_seq_cst); }
+
+ __pointer_type
+ operator--() volatile noexcept
+ { return __atomic_sub_fetch(&_M_p, _M_type_size(1),
+ memory_order_seq_cst); }
+
+ __pointer_type
+ operator+=(ptrdiff_t __d) noexcept
+ { return __atomic_add_fetch(&_M_p, _M_type_size(__d),
+ memory_order_seq_cst); }
+
+ __pointer_type
+ operator+=(ptrdiff_t __d) volatile noexcept
+ { return __atomic_add_fetch(&_M_p, _M_type_size(__d),
+ memory_order_seq_cst); }
+
+ __pointer_type
+ operator-=(ptrdiff_t __d) noexcept
+ { return __atomic_sub_fetch(&_M_p, _M_type_size(__d),
+ memory_order_seq_cst); }
+
+ __pointer_type
+ operator-=(ptrdiff_t __d) volatile noexcept
+ { return __atomic_sub_fetch(&_M_p, _M_type_size(__d),
+ memory_order_seq_cst); }
+
+ bool
+ is_lock_free() const noexcept
+ { return __atomic_is_lock_free(_M_type_size(1), &_M_p); }
+
+ bool
+ is_lock_free() const volatile noexcept
+ { return __atomic_is_lock_free(_M_type_size(1), &_M_p); }
+
+ void
+ store(__pointer_type __p,
+ memory_order __m = memory_order_seq_cst) noexcept
+ {
+ __glibcxx_assert(__m != memory_order_acquire);
+ __glibcxx_assert(__m != memory_order_acq_rel);
+ __glibcxx_assert(__m != memory_order_consume);
+
+ __atomic_store_n(&_M_p, __p, __m);
+ }
+
+ void
+ store(__pointer_type __p,
+ memory_order __m = memory_order_seq_cst) volatile noexcept
+ {
+ __glibcxx_assert(__m != memory_order_acquire);
+ __glibcxx_assert(__m != memory_order_acq_rel);
+ __glibcxx_assert(__m != memory_order_consume);
+
+ __atomic_store_n(&_M_p, __p, __m);
+ }
+
+ __pointer_type
+ load(memory_order __m = memory_order_seq_cst) const noexcept
+ {
+ __glibcxx_assert(__m != memory_order_release);
+ __glibcxx_assert(__m != memory_order_acq_rel);
+
+ return __atomic_load_n(&_M_p, __m);
+ }
+
+ __pointer_type
+ load(memory_order __m = memory_order_seq_cst) const volatile noexcept
+ {
+ __glibcxx_assert(__m != memory_order_release);
+ __glibcxx_assert(__m != memory_order_acq_rel);
+
+ return __atomic_load_n(&_M_p, __m);
+ }
+
+ __pointer_type
+ exchange(__pointer_type __p,
+ memory_order __m = memory_order_seq_cst) noexcept
+ {
+ return __atomic_exchange_n(&_M_p, __p, __m);
+ }
+
+
+ __pointer_type
+ exchange(__pointer_type __p,
+ memory_order __m = memory_order_seq_cst) volatile noexcept
+ {
+ return __atomic_exchange_n(&_M_p, __p, __m);
+ }
+
+ bool
+ compare_exchange_strong(__pointer_type& __p1, __pointer_type __p2,
+ memory_order __m1,
+ memory_order __m2) noexcept
+ {
+ __glibcxx_assert(__m2 != memory_order_release);
+ __glibcxx_assert(__m2 != memory_order_acq_rel);
+ __glibcxx_assert(__m2 <= __m1);
+
+ return __atomic_compare_exchange_n(&_M_p, &__p1, __p2, 0, __m1, __m2);
+ }
+
+ bool
+ compare_exchange_strong(__pointer_type& __p1, __pointer_type __p2,
+ memory_order __m1,
+ memory_order __m2) volatile noexcept
+ {
+ __glibcxx_assert(__m2 != memory_order_release);
+ __glibcxx_assert(__m2 != memory_order_acq_rel);
+ __glibcxx_assert(__m2 <= __m1);
+
+ return __atomic_compare_exchange_n(&_M_p, &__p1, __p2, 0, __m1, __m2);
+ }
+
+ __pointer_type
+ fetch_add(ptrdiff_t __d,
+ memory_order __m = memory_order_seq_cst) noexcept
+ { return __atomic_fetch_add(&_M_p, _M_type_size(__d), __m); }
+
+ __pointer_type
+ fetch_add(ptrdiff_t __d,
+ memory_order __m = memory_order_seq_cst) volatile noexcept
+ { return __atomic_fetch_add(&_M_p, _M_type_size(__d), __m); }
+
+ __pointer_type
+ fetch_sub(ptrdiff_t __d,
+ memory_order __m = memory_order_seq_cst) noexcept
+ { return __atomic_fetch_sub(&_M_p, _M_type_size(__d), __m); }
+
+ __pointer_type
+ fetch_sub(ptrdiff_t __d,
+ memory_order __m = memory_order_seq_cst) volatile noexcept
+ { return __atomic_fetch_sub(&_M_p, _M_type_size(__d), __m); }
+ };
+