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[StructurizeCFG] Introduce struct PredInfo. NFC. #115457

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Nov 8, 2024
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[StructurizeCFG] Introduce struct PredInfo. NFC. #115457

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57 changes: 25 additions & 32 deletions llvm/lib/Transforms/Scalar/StructurizeCFG.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -120,9 +120,12 @@ class CondBranchWeights {
}
};

using ValueWeightPair = std::pair<Value *, MaybeCondBranchWeights>;
struct PredInfo {
Value *Pred;
MaybeCondBranchWeights Weights;
};

using BBPredicates = DenseMap<BasicBlock *, ValueWeightPair>;
using BBPredicates = DenseMap<BasicBlock *, PredInfo>;
using PredMap = DenseMap<BasicBlock *, BBPredicates>;
using BB2BBMap = DenseMap<BasicBlock *, BasicBlock *>;

Expand Down Expand Up @@ -308,7 +311,7 @@ class StructurizeCFG {

void analyzeLoops(RegionNode *N);

ValueWeightPair buildCondition(BranchInst *Term, unsigned Idx, bool Invert);
PredInfo buildCondition(BranchInst *Term, unsigned Idx, bool Invert);

void gatherPredicates(RegionNode *N);

Expand Down Expand Up @@ -490,8 +493,8 @@ void StructurizeCFG::analyzeLoops(RegionNode *N) {
}

/// Build the condition for one edge
ValueWeightPair StructurizeCFG::buildCondition(BranchInst *Term, unsigned Idx,
bool Invert) {
PredInfo StructurizeCFG::buildCondition(BranchInst *Term, unsigned Idx,
bool Invert) {
Value *Cond = Invert ? BoolFalse : BoolTrue;
MaybeCondBranchWeights Weights;

Expand Down Expand Up @@ -624,24 +627,19 @@ void StructurizeCFG::insertConditions(bool Loops) {
NearestCommonDominator Dominator(DT);
Dominator.addBlock(Parent);

Value *ParentValue = nullptr;
MaybeCondBranchWeights ParentWeights = std::nullopt;
for (std::pair<BasicBlock *, ValueWeightPair> BBAndPred : Preds) {
BasicBlock *BB = BBAndPred.first;
auto [Pred, Weight] = BBAndPred.second;

PredInfo ParentInfo{nullptr, std::nullopt};
for (auto [BB, PI] : Preds) {
if (BB == Parent) {
ParentValue = Pred;
ParentWeights = Weight;
ParentInfo = PI;
break;
}
PhiInserter.AddAvailableValue(BB, Pred);
PhiInserter.AddAvailableValue(BB, PI.Pred);
Dominator.addAndRememberBlock(BB);
}

if (ParentValue) {
Term->setCondition(ParentValue);
CondBranchWeights::setMetadata(*Term, ParentWeights);
if (ParentInfo.Pred) {
Term->setCondition(ParentInfo.Pred);
CondBranchWeights::setMetadata(*Term, ParentInfo.Weights);
} else {
if (!Dominator.resultIsRememberedBlock())
PhiInserter.AddAvailableValue(Dominator.result(), Default);
Expand All @@ -656,15 +654,14 @@ void StructurizeCFG::simplifyConditions() {
SmallVector<Instruction *> InstToErase;
for (auto &I : concat<PredMap::value_type>(Predicates, LoopPreds)) {
auto &Preds = I.second;
for (auto &J : Preds) {
Value *Cond = J.second.first;
for (auto [BB, PI] : Preds) {
Instruction *Inverted;
if (match(Cond, m_Not(m_OneUse(m_Instruction(Inverted)))) &&
!Cond->use_empty()) {
if (match(PI.Pred, m_Not(m_OneUse(m_Instruction(Inverted)))) &&
!PI.Pred->use_empty()) {
if (auto *InvertedCmp = dyn_cast<CmpInst>(Inverted)) {
InvertedCmp->setPredicate(InvertedCmp->getInversePredicate());
Cond->replaceAllUsesWith(InvertedCmp);
InstToErase.push_back(cast<Instruction>(Cond));
PI.Pred->replaceAllUsesWith(InvertedCmp);
InstToErase.push_back(cast<Instruction>(PI.Pred));
}
}
}
Expand Down Expand Up @@ -1046,10 +1043,9 @@ void StructurizeCFG::setPrevNode(BasicBlock *BB) {
/// Does BB dominate all the predicates of Node?
bool StructurizeCFG::dominatesPredicates(BasicBlock *BB, RegionNode *Node) {
BBPredicates &Preds = Predicates[Node->getEntry()];
return llvm::all_of(Preds,
[&](std::pair<BasicBlock *, ValueWeightPair> Pred) {
return DT->dominates(BB, Pred.first);
});
return llvm::all_of(Preds, [&](std::pair<BasicBlock *, PredInfo> Pred) {
return DT->dominates(BB, Pred.first);
});
}

/// Can we predict that this node will always be called?
Expand All @@ -1061,11 +1057,8 @@ bool StructurizeCFG::isPredictableTrue(RegionNode *Node) {
if (!PrevNode)
return true;

for (std::pair<BasicBlock *, ValueWeightPair> Pred : Preds) {
BasicBlock *BB = Pred.first;
Value *V = Pred.second.first;

if (V != BoolTrue)
for (auto [BB, PI] : Preds) {
if (PI.Pred != BoolTrue)
return false;

if (!Dominated && DT->dominates(BB, PrevNode->getEntry()))
Expand Down
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