Fix rdar://6505632, an llc crash on 483.xalancbmk


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62470 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/CodeGenPrepare.cpp b/lib/Transforms/Scalar/CodeGenPrepare.cpp
index be7ed9c..59c6586 100644
--- a/lib/Transforms/Scalar/CodeGenPrepare.cpp
+++ b/lib/Transforms/Scalar/CodeGenPrepare.cpp
@@ -688,7 +688,8 @@
   // to see if ScaleReg is actually X+C.  If so, we can turn this into adding
   // X*Scale + C*Scale to addr mode.
   ConstantInt *CI; Value *AddLHS;
-  if (match(ScaleReg, m_Add(m_Value(AddLHS), m_ConstantInt(CI)))) {
+  if (isa<Instruction>(ScaleReg) &&  // not a constant expr.
+      match(ScaleReg, m_Add(m_Value(AddLHS), m_ConstantInt(CI)))) {
     TestAddrMode.ScaledReg = AddLHS;
     TestAddrMode.BaseOffs += CI->getSExtValue()*TestAddrMode.Scale;