indvars -disable-iv-rewrite: just because SCEV ignores casts doesn't
mean they can be removed.

llvm-svn: 134054
diff --git a/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp b/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
index 8986dbb..919da35 100644
--- a/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
+++ b/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
@@ -1007,6 +1007,7 @@
 
   // Eliminate any operation that SCEV can prove is an identity function.
   if (!SE->isSCEVable(UseInst->getType()) ||
+      (UseInst->getType() != IVOperand->getType()) ||
       (SE->getSCEV(UseInst) != SE->getSCEV(IVOperand)))
     return false;