1 files changed, 6 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
index ca1885a6128..9187c70fb84 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
@@ -934,6 +934,12 @@ Instruction *InstCombiner::visitShl(BinaryOperator &I) {
     return BinaryOperator::CreateLShr(
         ConstantInt::get(Ty, APInt::getSignMask(BitWidth)), X);
 
+  // shl (zext (i1 X)), C1 --> select (X, 1 << C1, 0)
+  if (match(Op0, m_ZExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)) {
+    auto *NewC = ConstantExpr::getShl(ConstantInt::get(Ty, 1), C1);
+    return SelectInst::Create(X, NewC, ConstantInt::getNullValue(Ty));
+  }
+
   return nullptr;
 }