InstSimplify: Don't simplify gep X, (Y-X) to Y if types differ

It's incorrect to perform this simplification if the types differ.
A bitcast would need to be inserted for this to work.

This fixes PR20771.

llvm-svn: 216597

1 files changed, 2 insertions, 1 deletions

diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 118579d..9f3b2876 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -2837,7 +2837,8 @@ static Value *SimplifyGEPInst(ArrayRef<Value *> Ops, const Query &Q, unsigned) {
             return Constant::getNullValue(GEPTy);
           Value *Temp;
           if (match(P, m_PtrToInt(m_Value(Temp))))
-            return Temp;
+            if (Temp->getType() == GEPTy)
+              return Temp;
           return nullptr;
         };