for completeness, allow undef also.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112351 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/InstCombine/InstCombineCasts.cpp b/lib/Transforms/InstCombine/InstCombineCasts.cpp
index 0434d6b..6c2477d 100644
--- a/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -1381,6 +1381,9 @@
static bool CollectInsertionElements(Value *V, unsigned ElementIndex,
SmallVectorImpl<Value*> &Elements,
const Type *VecEltTy) {
+ // Undef values never contribute useful bits to the result.
+ if (isa<UndefValue>(V)) return true;
+
// If we got down to a value of the right type, we win, try inserting into the
// right element.
if (V->getType() == VecEltTy) {