InstCombine: Don't create an unused instruction

We would create an instruction but not inserting it.
Not inserting the unused instruction would lead us to verification
failure.

This fixes PR21653.

llvm-svn: 222659

1 files changed, 1 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index d7847ca5ccd..3956869e2d3 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -300,8 +300,7 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) {
     if (match(Op0, m_Shl(m_One(), m_Value(Y)))) {
       BO = BinaryOperator::CreateShl(Op1, Y);
       ShlNSW = cast<BinaryOperator>(Op0)->hasNoSignedWrap();
-    }
-    if (match(Op1, m_Shl(m_One(), m_Value(Y)))) {
+    } else if (match(Op1, m_Shl(m_One(), m_Value(Y)))) {
       BO = BinaryOperator::CreateShl(Op0, Y);
       ShlNSW = cast<BinaryOperator>(Op1)->hasNoSignedWrap();
     }