Fixed scalarizing an extract subvector and prevent an infinite loop
when simplify a vector.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58820 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 3210b12..743d8bb 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -1410,6 +1410,12 @@
} else if (isa<ConstantAggregateZero>(V)) {
// Simplify the CAZ to a ConstantVector where the non-demanded elements are
// set to undef.
+
+ // Check if this is identity. If so, return 0 since we are not simplifying
+ // anything.
+ if (DemandedElts == ((1ULL << VWidth) -1))
+ return 0;
+
const Type *EltTy = cast<VectorType>(V->getType())->getElementType();
Constant *Zero = Constant::getNullValue(EltTy);
Constant *Undef = UndefValue::get(EltTy);