[SimplifyCFG] Update (AND) IR flags when CSE'ing instructions
We were updating metadata but not IR flags. Because we pick an arbitrary instruction to be the CSE candidate, it comes down to luck (50% or less chance) if this results in broken codegen or not, which is why PR30373 which is actually not the fault of the commit it was bisected down to.
Fixes PR30373.
llvm-svn: 281889
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 877e559..90ce672 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1527,10 +1527,12 @@
I0->getOperandUse(O).set(NewOperands[O]);
I0->moveBefore(&*BBEnd->getFirstInsertionPt());
- // Update metadata.
+ // Update metadata and IR flags.
for (auto *I : Insts)
- if (I != I0)
+ if (I != I0) {
combineMetadataForCSE(I0, I);
+ I0->andIRFlags(I);
+ }
if (!isa<StoreInst>(I0)) {
// canSinkLastInstruction checked that all instructions were used by