TargetLowering: Don't index into empty string.

(This is triggered by current lit tests) git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192549 91177308-0d34-0410-b5e6-96231b3b80d8
Bigcheese · Oct 13, 2013 · 833a29c · 833a29c
1 parent 6dd7893
commit 833a29c
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -2012,7 +2012,7 @@ void TargetLowering::LowerAsmOperandForConstraint(SDValue Op,
 std::pair<unsigned, const TargetRegisterClass*> TargetLowering::
 getRegForInlineAsmConstraint(const std::string &Constraint,
                              MVT VT) const {
-  if (Constraint[0] != '{')
+  if (Constraint.empty() || Constraint[0] != '{')
     return std::make_pair(0u, static_cast<TargetRegisterClass*>(0));
   assert(*(Constraint.end()-1) == '}' && "Not a brace enclosed constraint?");