[libc++] constexpr atomic and atomic_ref

Author: hanickadot

libcxx/include/__atomic/atomic.h

@@ -40,38 +40,40 @@ struct __atomic_base // false
     return __cxx_atomic_is_lock_free(sizeof(__cxx_atomic_impl<_Tp>));
   }
   _LIBCPP_HIDE_FROM_ABI bool is_lock_free() const _NOEXCEPT {
-    return static_cast<__atomic_base const volatile*>(this)->is_lock_free();
+    return __cxx_atomic_is_lock_free(sizeof(__cxx_atomic_impl<_Tp>));
   }
   _LIBCPP_HIDE_FROM_ABI void store(_Tp __d, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
       _LIBCPP_CHECK_STORE_MEMORY_ORDER(__m) {
     std::__cxx_atomic_store(std::addressof(__a_), __d, __m);
   }
-  _LIBCPP_HIDE_FROM_ABI void store(_Tp __d, memory_order __m = memory_order_seq_cst) _NOEXCEPT
-      _LIBCPP_CHECK_STORE_MEMORY_ORDER(__m) {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void
+  store(_Tp __d, memory_order __m = memory_order_seq_cst) _NOEXCEPT _LIBCPP_CHECK_STORE_MEMORY_ORDER(__m) {
     std::__cxx_atomic_store(std::addressof(__a_), __d, __m);
   }
   _LIBCPP_HIDE_FROM_ABI _Tp load(memory_order __m = memory_order_seq_cst) const volatile _NOEXCEPT
       _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m) {
     return std::__cxx_atomic_load(std::addressof(__a_), __m);
   }
-  _LIBCPP_HIDE_FROM_ABI _Tp load(memory_order __m = memory_order_seq_cst) const _NOEXCEPT
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp load(memory_order __m = memory_order_seq_cst) const _NOEXCEPT
       _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m) {
     return std::__cxx_atomic_load(std::addressof(__a_), __m);
   }
   _LIBCPP_HIDE_FROM_ABI operator _Tp() const volatile _NOEXCEPT { return load(); }
-  _LIBCPP_HIDE_FROM_ABI operator _Tp() const _NOEXCEPT { return load(); }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 operator _Tp() const _NOEXCEPT { return load(); }
   _LIBCPP_HIDE_FROM_ABI _Tp exchange(_Tp __d, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT {
     return std::__cxx_atomic_exchange(std::addressof(__a_), __d, __m);
   }
-  _LIBCPP_HIDE_FROM_ABI _Tp exchange(_Tp __d, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp
+  exchange(_Tp __d, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
     return std::__cxx_atomic_exchange(std::addressof(__a_), __d, __m);
   }
   _LIBCPP_HIDE_FROM_ABI bool
   compare_exchange_weak(_Tp& __e, _Tp __d, memory_order __s, memory_order __f) volatile _NOEXCEPT
       _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f) {
     return std::__cxx_atomic_compare_exchange_weak(std::addressof(__a_), std::addressof(__e), __d, __s, __f);
   }
-  _LIBCPP_HIDE_FROM_ABI bool compare_exchange_weak(_Tp& __e, _Tp __d, memory_order __s, memory_order __f) _NOEXCEPT
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 bool
+  compare_exchange_weak(_Tp& __e, _Tp __d, memory_order __s, memory_order __f) _NOEXCEPT
       _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f) {
     return std::__cxx_atomic_compare_exchange_weak(std::addressof(__a_), std::addressof(__e), __d, __s, __f);
   }
@@ -80,23 +82,24 @@ struct __atomic_base // false
       _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f) {
     return std::__cxx_atomic_compare_exchange_strong(std::addressof(__a_), std::addressof(__e), __d, __s, __f);
   }
-  _LIBCPP_HIDE_FROM_ABI bool compare_exchange_strong(_Tp& __e, _Tp __d, memory_order __s, memory_order __f) _NOEXCEPT
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 bool
+  compare_exchange_strong(_Tp& __e, _Tp __d, memory_order __s, memory_order __f) _NOEXCEPT
       _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f) {
     return std::__cxx_atomic_compare_exchange_strong(std::addressof(__a_), std::addressof(__e), __d, __s, __f);
   }
   _LIBCPP_HIDE_FROM_ABI bool
   compare_exchange_weak(_Tp& __e, _Tp __d, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT {
     return std::__cxx_atomic_compare_exchange_weak(std::addressof(__a_), std::addressof(__e), __d, __m, __m);
   }
-  _LIBCPP_HIDE_FROM_ABI bool
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 bool
   compare_exchange_weak(_Tp& __e, _Tp __d, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
     return std::__cxx_atomic_compare_exchange_weak(std::addressof(__a_), std::addressof(__e), __d, __m, __m);
   }
   _LIBCPP_HIDE_FROM_ABI bool
   compare_exchange_strong(_Tp& __e, _Tp __d, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT {
     return std::__cxx_atomic_compare_exchange_strong(std::addressof(__a_), std::addressof(__e), __d, __m, __m);
   }
-  _LIBCPP_HIDE_FROM_ABI bool
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 bool
   compare_exchange_strong(_Tp& __e, _Tp __d, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
     return std::__cxx_atomic_compare_exchange_strong(std::addressof(__a_), std::addressof(__e), __d, __m, __m);
   }
@@ -105,23 +108,37 @@ struct __atomic_base // false
       volatile _NOEXCEPT {
     std::__atomic_wait(*this, __v, __m);
   }
-  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void
+  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void
   wait(_Tp __v, memory_order __m = memory_order_seq_cst) const _NOEXCEPT {
-    std::__atomic_wait(*this, __v, __m);
+    if (__libcpp_is_constant_evaluated()) {
+      if (this->load(__m) != __v) {
+        __builtin_trap();
+      }
+    } else {
+      std::__atomic_wait(*this, __v, __m);
+    }
   }
   _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void notify_one() volatile _NOEXCEPT {
     std::__atomic_notify_one(*this);
   }
-  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void notify_one() _NOEXCEPT { std::__atomic_notify_one(*this); }
+  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void notify_one() _NOEXCEPT {
+    if !consteval {
+      std::__atomic_notify_one(*this);
+    }
+  }
   _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void notify_all() volatile _NOEXCEPT {
     std::__atomic_notify_all(*this);
   }
-  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void notify_all() _NOEXCEPT { std::__atomic_notify_all(*this); }
+  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void notify_all() _NOEXCEPT {
+    if !consteval {
+      std::__atomic_notify_all(*this);
+    }
+  }
 
 #if _LIBCPP_STD_VER >= 20
   _LIBCPP_HIDE_FROM_ABI constexpr __atomic_base() noexcept(is_nothrow_default_constructible_v<_Tp>) : __a_(_Tp()) {}
 #else
-  _LIBCPP_HIDE_FROM_ABI __atomic_base() _NOEXCEPT = default;
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __atomic_base() _NOEXCEPT = default;
 #endif
 
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __atomic_base(_Tp __d) _NOEXCEPT : __a_(__d) {}
@@ -142,52 +159,67 @@ struct __atomic_base<_Tp, true> : public __atomic_base<_Tp, false> {
   _LIBCPP_HIDE_FROM_ABI _Tp fetch_add(_Tp __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT {
     return std::__cxx_atomic_fetch_add(std::addressof(this->__a_), __op, __m);
   }
-  _LIBCPP_HIDE_FROM_ABI _Tp fetch_add(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp
+  fetch_add(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
     return std::__cxx_atomic_fetch_add(std::addressof(this->__a_), __op, __m);
   }
   _LIBCPP_HIDE_FROM_ABI _Tp fetch_sub(_Tp __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT {
     return std::__cxx_atomic_fetch_sub(std::addressof(this->__a_), __op, __m);
   }
-  _LIBCPP_HIDE_FROM_ABI _Tp fetch_sub(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp
+  fetch_sub(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
     return std::__cxx_atomic_fetch_sub(std::addressof(this->__a_), __op, __m);
   }
   _LIBCPP_HIDE_FROM_ABI _Tp fetch_and(_Tp __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT {
     return std::__cxx_atomic_fetch_and(std::addressof(this->__a_), __op, __m);
   }
-  _LIBCPP_HIDE_FROM_ABI _Tp fetch_and(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp
+  fetch_and(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
     return std::__cxx_atomic_fetch_and(std::addressof(this->__a_), __op, __m);
   }
   _LIBCPP_HIDE_FROM_ABI _Tp fetch_or(_Tp __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT {
     return std::__cxx_atomic_fetch_or(std::addressof(this->__a_), __op, __m);
   }
-  _LIBCPP_HIDE_FROM_ABI _Tp fetch_or(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp
+  fetch_or(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
     return std::__cxx_atomic_fetch_or(std::addressof(this->__a_), __op, __m);
   }
   _LIBCPP_HIDE_FROM_ABI _Tp fetch_xor(_Tp __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT {
     return std::__cxx_atomic_fetch_xor(std::addressof(this->__a_), __op, __m);
   }
-  _LIBCPP_HIDE_FROM_ABI _Tp fetch_xor(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp
+  fetch_xor(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
     return std::__cxx_atomic_fetch_xor(std::addressof(this->__a_), __op, __m);
   }
 
   _LIBCPP_HIDE_FROM_ABI _Tp operator++(int) volatile _NOEXCEPT { return fetch_add(_Tp(1)); }
-  _LIBCPP_HIDE_FROM_ABI _Tp operator++(int) _NOEXCEPT { return fetch_add(_Tp(1)); }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp operator++(int) _NOEXCEPT { return fetch_add(_Tp(1)); }
   _LIBCPP_HIDE_FROM_ABI _Tp operator--(int) volatile _NOEXCEPT { return fetch_sub(_Tp(1)); }
-  _LIBCPP_HIDE_FROM_ABI _Tp operator--(int) _NOEXCEPT { return fetch_sub(_Tp(1)); }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp operator--(int) _NOEXCEPT { return fetch_sub(_Tp(1)); }
   _LIBCPP_HIDE_FROM_ABI _Tp operator++() volatile _NOEXCEPT { return fetch_add(_Tp(1)) + _Tp(1); }
-  _LIBCPP_HIDE_FROM_ABI _Tp operator++() _NOEXCEPT { return fetch_add(_Tp(1)) + _Tp(1); }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp operator++() _NOEXCEPT { return fetch_add(_Tp(1)) + _Tp(1); }
   _LIBCPP_HIDE_FROM_ABI _Tp operator--() volatile _NOEXCEPT { return fetch_sub(_Tp(1)) - _Tp(1); }
-  _LIBCPP_HIDE_FROM_ABI _Tp operator--() _NOEXCEPT { return fetch_sub(_Tp(1)) - _Tp(1); }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp operator--() _NOEXCEPT { return fetch_sub(_Tp(1)) - _Tp(1); }
   _LIBCPP_HIDE_FROM_ABI _Tp operator+=(_Tp __op) volatile _NOEXCEPT { return fetch_add(__op) + __op; }
-  _LIBCPP_HIDE_FROM_ABI _Tp operator+=(_Tp __op) _NOEXCEPT { return fetch_add(__op) + __op; }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp operator+=(_Tp __op) _NOEXCEPT {
+    return fetch_add(__op) + __op;
+  }
   _LIBCPP_HIDE_FROM_ABI _Tp operator-=(_Tp __op) volatile _NOEXCEPT { return fetch_sub(__op) - __op; }
-  _LIBCPP_HIDE_FROM_ABI _Tp operator-=(_Tp __op) _NOEXCEPT { return fetch_sub(__op) - __op; }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp operator-=(_Tp __op) _NOEXCEPT {
+    return fetch_sub(__op) - __op;
+  }
   _LIBCPP_HIDE_FROM_ABI _Tp operator&=(_Tp __op) volatile _NOEXCEPT { return fetch_and(__op) & __op; }
-  _LIBCPP_HIDE_FROM_ABI _Tp operator&=(_Tp __op) _NOEXCEPT { return fetch_and(__op) & __op; }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp operator&=(_Tp __op) _NOEXCEPT {
+    return fetch_and(__op) & __op;
+  }
   _LIBCPP_HIDE_FROM_ABI _Tp operator|=(_Tp __op) volatile _NOEXCEPT { return fetch_or(__op) | __op; }
-  _LIBCPP_HIDE_FROM_ABI _Tp operator|=(_Tp __op) _NOEXCEPT { return fetch_or(__op) | __op; }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp operator|=(_Tp __op) _NOEXCEPT {
+    return fetch_or(__op) | __op;
+  }
   _LIBCPP_HIDE_FROM_ABI _Tp operator^=(_Tp __op) volatile _NOEXCEPT { return fetch_xor(__op) ^ __op; }
-  _LIBCPP_HIDE_FROM_ABI _Tp operator^=(_Tp __op) _NOEXCEPT { return fetch_xor(__op) ^ __op; }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp operator^=(_Tp __op) _NOEXCEPT {
+    return fetch_xor(__op) ^ __op;
+  }
 };
 
 // Here we need _IsIntegral because the default template argument is not enough
@@ -196,7 +228,8 @@ struct __atomic_base<_Tp, true> : public __atomic_base<_Tp, false> {
 // __atomic_base<int, false>. So specializing __atomic_base<_Tp> does not work
 template <class _Tp, bool _IsIntegral>
 struct __atomic_waitable_traits<__atomic_base<_Tp, _IsIntegral> > {
-  static _LIBCPP_HIDE_FROM_ABI _Tp __atomic_load(const __atomic_base<_Tp, _IsIntegral>& __a, memory_order __order) {
+  static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 _Tp
+  __atomic_load(const __atomic_base<_Tp, _IsIntegral>& __a, memory_order __order) {
     return __a.load(__order);
   }
 
@@ -205,7 +238,7 @@ struct __atomic_waitable_traits<__atomic_base<_Tp, _IsIntegral> > {
     return __this.load(__order);
   }
 
-  static _LIBCPP_HIDE_FROM_ABI const __cxx_atomic_impl<_Tp>*
+  static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 const __cxx_atomic_impl<_Tp>*
   __atomic_contention_address(const __atomic_base<_Tp, _IsIntegral>& __a) {
     return std::addressof(__a.__a_);
   }