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
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 05b025c..17631c0 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -2012,7 +2012,7 @@
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?");