[AggressiveInstCombine] Create zext during store merge (#181125)

The top extracted value can include shifted-in zero bits. In that case
we should emit a zext before the new store.

Fixes https://github.com/llvm/llvm-project/issues/181117.

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp b/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
index 3341368208c2..797fabde3f25 100644
--- a/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
+++ b/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
@@ -915,7 +915,7 @@ static bool mergeConsecutivePartStores(ArrayRef<PartStore> Parts,
   Value *Val = First.Val;
   if (First.ValOffset != 0)
     Val = Builder.CreateLShr(Val, First.ValOffset);
-  Val = Builder.CreateTrunc(Val, NewTy);
+  Val = Builder.CreateZExtOrTrunc(Val, NewTy);
   StoreInst *Store = Builder.CreateAlignedStore(
       Val, First.Store->getPointerOperand(), First.Store->getAlign());