1 files changed, 7 insertions, 0 deletions
diff --git a/clang/lib/Basic/TargetInfo.cpp b/clang/lib/Basic/TargetInfo.cpp
index f2dc84fa034..aabb70dd6b1 100644
--- a/clang/lib/Basic/TargetInfo.cpp
+++ b/clang/lib/Basic/TargetInfo.cpp
@@ -459,7 +459,9 @@ bool TargetInfo::validateOutputConstraint(ConstraintInfo &Info) const {
         // Eventually, an unknown constraint should just be treated as 'g'.
         return false;
       }
+      break;
     case '&': // early clobber.
+      Info.setEarlyClobber();
       break;
     case '%': // commutative.
       // FIXME: Check that there is a another register after this one.
@@ -494,6 +496,11 @@ bool TargetInfo::validateOutputConstraint(ConstraintInfo &Info) const {
     Name++;
   }
 
+  // Early clobber with a read-write constraint which doesn't permit registers
+  // is invalid.
+  if (Info.earlyClobber() && Info.isReadWrite() && !Info.allowsRegister())
+    return false;
+
   // If a constraint allows neither memory nor register operands it contains
   // only modifiers. Reject it.
   return Info.allowsMemory() || Info.allowsRegister();