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[constant-folding] Eliminate complexity introducing pre-mature optimization. #27997

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Merged
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Oct 31, 2019
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[constant-folding] Eliminate complexity introducing pre-mature optimization. #27997

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45 changes: 1 addition & 44 deletions lib/SILOptimizer/Utils/ConstantFolding.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1939,51 +1939,8 @@ ConstantFolder::processWorkList() {
// Ok, we have succeeded. Add user to the FoldedUsers list and perform
// the necessary cleanups, RAUWs, etc.
FoldedUsers.insert(User);
++NumInstFolded;

InvalidateInstructions = true;

// If the constant produced a tuple, be smarter than RAUW: explicitly
// nuke any tuple_extract instructions using the apply. This is a
// common case for functions returning multiple values.
if (auto *TI = dyn_cast<TupleInst>(C)) {
for (SILValue Result : User->getResults()) {
for (auto UI = Result->use_begin(), UE = Result->use_end();
UI != UE;) {
Operand *O = *UI++;

// If the user is a tuple_extract, just substitute the right
// value in.
if (auto *TEI = dyn_cast<TupleExtractInst>(O->getUser())) {
SILValue NewVal = TI->getOperand(TEI->getFieldNo());
TEI->replaceAllUsesWith(NewVal);
TEI->dropAllReferences();
FoldedUsers.insert(TEI);
if (auto *Inst = NewVal->getDefiningInstruction())
WorkList.insert(Inst);
continue;
}

if (auto *DTI = dyn_cast<DestructureTupleInst>(O->getUser())) {
SILValue NewVal = TI->getOperand(O->getOperandNumber());
auto OwnershipKind = NewVal.getOwnershipKind();
if (OwnershipKind.isCompatibleWith(
ValueOwnershipKind::Guaranteed)) {
SILValue DTIResult = DTI->getResult(O->getOperandNumber());
DTIResult->replaceAllUsesWith(NewVal);
FoldedUsers.insert(DTI);
if (auto *Inst = NewVal->getDefiningInstruction())
WorkList.insert(Inst);
continue;
}
}
}
}

if (llvm::all_of(User->getResults(),
[](SILValue v) { return v->use_empty(); }))
FoldedUsers.insert(TI);
}
++NumInstFolded;

// We were able to fold, so all users should use the new folded
// value. If we don't have any such users, continue.
Expand Down