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[DSE] Avoid calling isRemovable() on non-analyzable location (NFC) 

At this point the instruction may either have an analyzable
write or be a terminator. For terminators, isRemovable() is not
necessarily well-defined. Move the check until after we have ensured
that it is not a terminator.
This commit is contained in:
Nikita Popov 2021-12-24 10:14:55 +01:00
parent 81d69e1bda
commit 2b8a703858
1 changed files with 10 additions and 5 deletions
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15
llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
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@ -1704,13 +1704,19 @@ struct DSEState {
/// \returns true if \p Def is a no-op store, either because it
/// directly stores back a loaded value or stores zero to a calloced object.
bool storeIsNoop(MemoryDef *Def, const Value *DefUO) {
StoreInst *Store = dyn_cast<StoreInst>(Def->getMemoryInst());
MemSetInst *MemSet = dyn_cast<MemSetInst>(Def->getMemoryInst());
Instruction *DefI = Def->getMemoryInst();
StoreInst *Store = dyn_cast<StoreInst>(DefI);
MemSetInst *MemSet = dyn_cast<MemSetInst>(DefI);
Constant *StoredConstant = nullptr;
if (Store)
StoredConstant = dyn_cast<Constant>(Store->getOperand(0));
if (MemSet)
else if (MemSet)
StoredConstant = dyn_cast<Constant>(MemSet->getValue());
else
return false;
if (!isRemovable(DefI))
return false;
if (StoredConstant && StoredConstant->isNullValue()) {
auto *DefUOInst = dyn_cast<Instruction>(DefUO);
@ -2065,8 +2071,7 @@ static bool eliminateDeadStores(Function &F, AliasAnalysis &AA, MemorySSA &MSSA,
}
// Check if the store is a no-op.
if (!Shortend && isRemovable(KillingI) &&
State.storeIsNoop(KillingDef, KillingUndObj)) {
if (!Shortend && State.storeIsNoop(KillingDef, KillingUndObj)) {
LLVM_DEBUG(dbgs() << "DSE: Remove No-Op Store:\n DEAD: " << *KillingI
<< '\n');
State.deleteDeadInstruction(KillingI);