eliminate warning

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@42892 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 9e29057..2c88279 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -8643,7 +8643,7 @@
       // converted to match the type of the cast, don't touch this.
       if (isa<AllocationInst>(BCI->getOperand(0))) {
         // See if the bitcast simplifies, if so, don't nuke this GEP yet.
-        if (Instruction *I = visitBitCast(*BCI))
+        if (visitBitCast(*BCI))
           return &GEP;
       }
       return new BitCastInst(BCI->getOperand(0), GEP.getType());