[libc++][atomic_ref] Attempt to use __cxx_atomic_wait

Author: dalg24

libcxx/include/__atomic/atomic_ref.h

@@ -18,6 +18,7 @@
 #define _LIBCPP___ATOMIC_ATOMIC_REF_H
 
 #include <__assert>
+#include <__atomic/atomic_sync.h>
 #include <__atomic/check_memory_order.h>
 #include <__atomic/to_gcc_order.h>
 #include <__config>
@@ -143,16 +144,10 @@ struct __atomic_ref_base {
         __order == memory_order::relaxed || __order == memory_order::consume || __order == memory_order::acquire ||
             __order == memory_order::seq_cst,
         "memory order argument to atomic wait operation is invalid");
-    // FIXME
-    (void)__old;
-    (void)__order;
-  }
-  _LIBCPP_HIDE_FROM_ABI void notify_one() const noexcept {
-    // FIXME
-  }
-  _LIBCPP_HIDE_FROM_ABI void notify_all() const noexcept {
-    // FIXME
+    __cxx_atomic_wait(__ptr_, __old, __order);
   }
+  _LIBCPP_HIDE_FROM_ABI void notify_one() const noexcept { __cxx_atomic_notify_one(__ptr_); }
+  _LIBCPP_HIDE_FROM_ABI void notify_all() const noexcept { __cxx_atomic_notify_all(__ptr_); }
 
   _LIBCPP_HIDE_FROM_ABI __atomic_ref_base(_Tp& __obj) : __ptr_(&__obj) {}
 };

libcxx/include/__atomic/atomic_sync.h

@@ -27,6 +27,21 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
+template <class _Tp>
+struct __is_cxx_atomic_impl : false_type {};
+
+template <class _Tp>
+struct __is_cxx_atomic_impl<__cxx_atomic_impl<_Tp> > : true_type {};
+
+template <class _Tp>
+_LIBCPP_HIDE_FROM_ABI __enable_if_t<!__is_cxx_atomic_impl<__remove_cv_t<_Tp> >::value, _Tp>
+__cxx_atomic_load(_Tp* __ptr, memory_order __order) noexcept {
+  alignas(_Tp) unsigned char __mem[sizeof(_Tp)];
+  auto* __ret = reinterpret_cast<_Tp*>(__mem);
+  __atomic_load(__ptr, __ret, __to_gcc_order(__order));
+  return *__ret;
+}
+
 #ifndef _LIBCPP_HAS_NO_THREADS
 
 _LIBCPP_AVAILABILITY_SYNC _LIBCPP_EXPORTED_FROM_ABI void __cxx_atomic_notify_one(void const volatile*);

libcxx/test/std/atomics/atomics.ref/notify_all.pass.cpp

@@ -6,7 +6,6 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
-// XFAIL: *
 
 // void notify_all() const noexcept;
 

libcxx/test/std/atomics/atomics.ref/notify_one.pass.cpp

@@ -6,7 +6,6 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
-// XFAIL: *
 
 // void notify_one() const noexcept;
 

libcxx/test/std/atomics/atomics.ref/wait.pass.cpp

@@ -6,7 +6,6 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
-// XFAIL: *
 
 // void wait(T, memory_order = memory_order::seq_cst) const noexcept;