1 files changed, 9 insertions, 4 deletions
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 7748b8c8a66..104134cdb0e 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -374,10 +374,6 @@ ExprResult Sema::DefaultLvalueConversion(Expr *E) {
   QualType T = E->getType();
   assert(!T.isNull() && "r-value conversion on typeless expression?");
 
-  // We can't do lvalue-to-rvalue on atomics yet.
-  if (T->isAtomicType())
-    return Owned(E);
-
   // We don't want to throw lvalue-to-rvalue casts on top of
   // expressions of certain types in C++.
   if (getLangOpts().CPlusPlus &&
@@ -413,6 +409,15 @@ ExprResult Sema::DefaultLvalueConversion(Expr *E) {
   ExprResult Res = Owned(ImplicitCastExpr::Create(Context, T, CK_LValueToRValue,
                                                   E, 0, VK_RValue));
 
+  // C11 6.3.2.1p2:
+  //   ... if the lvalue has atomic type, the value has the non-atomic version 
+  //   of the type of the lvalue ...
+  if (const AtomicType *Atomic = T->getAs<AtomicType>()) {
+    T = Atomic->getValueType().getUnqualifiedType();
+    Res = Owned(ImplicitCastExpr::Create(Context, T, CK_AtomicToNonAtomic,
+                                         Res.get(), 0, VK_RValue));
+  }
+  
   return Res;
 }