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[AMDGPU] Improve StructurizeCFG pass performance by using SSAUpdaterBulk. #150937

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Merged
merged 1 commit into from
Oct 14, 2025
+15 −10
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[AMDGPU] Improve StructurizeCFG pass performance by using SSAUpdaterBulk. #150937

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25 changes: 15 additions & 10 deletions llvm/lib/Transforms/Scalar/StructurizeCFG.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,7 @@
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/SSAUpdater.h"
#include "llvm/Transforms/Utils/SSAUpdaterBulk.h"
#include <cassert>
#include <utility>

Expand Down Expand Up @@ -321,7 +322,7 @@ class StructurizeCFG {

void collectInfos();

void insertConditions(bool Loops);
void insertConditions(bool Loops, SSAUpdaterBulk &PhiInserter);

void simplifyConditions();

Expand Down Expand Up @@ -671,10 +672,9 @@ void StructurizeCFG::collectInfos() {
}

/// Insert the missing branch conditions
void StructurizeCFG::insertConditions(bool Loops) {
void StructurizeCFG::insertConditions(bool Loops, SSAUpdaterBulk &PhiInserter) {
BranchVector &Conds = Loops ? LoopConds : Conditions;
Value *Default = Loops ? BoolTrue : BoolFalse;
SSAUpdater PhiInserter;

for (BranchInst *Term : Conds) {
assert(Term->isConditional());
Expand All @@ -683,8 +683,9 @@ void StructurizeCFG::insertConditions(bool Loops) {
BasicBlock *SuccTrue = Term->getSuccessor(0);
BasicBlock *SuccFalse = Term->getSuccessor(1);

PhiInserter.Initialize(Boolean, "");
PhiInserter.AddAvailableValue(Loops ? SuccFalse : Parent, Default);
unsigned Variable = PhiInserter.AddVariable("", Boolean);
PhiInserter.AddAvailableValue(Variable, Loops ? SuccFalse : Parent,
Default);

BBPredicates &Preds = Loops ? LoopPreds[SuccFalse] : Predicates[SuccTrue];

Expand All @@ -697,7 +698,7 @@ void StructurizeCFG::insertConditions(bool Loops) {
ParentInfo = PI;
break;
}
PhiInserter.AddAvailableValue(BB, PI.Pred);
PhiInserter.AddAvailableValue(Variable, BB, PI.Pred);
Dominator.addAndRememberBlock(BB);
}

Expand All @@ -706,9 +707,9 @@ void StructurizeCFG::insertConditions(bool Loops) {
CondBranchWeights::setMetadata(*Term, ParentInfo.Weights);
} else {
if (!Dominator.resultIsRememberedBlock())
PhiInserter.AddAvailableValue(Dominator.result(), Default);
PhiInserter.AddAvailableValue(Variable, Dominator.result(), Default);

Term->setCondition(PhiInserter.GetValueInMiddleOfBlock(Parent));
PhiInserter.AddUse(Variable, &Term->getOperandUse(0));
}
}
}
Expand Down Expand Up @@ -1414,8 +1415,12 @@ bool StructurizeCFG::run(Region *R, DominatorTree *DT,
orderNodes();
collectInfos();
createFlow();
insertConditions(false);
insertConditions(true);

SSAUpdaterBulk PhiInserter;
insertConditions(false, PhiInserter);
insertConditions(true, PhiInserter);
PhiInserter.RewriteAndOptimizeAllUses(*DT);

setPhiValues();
simplifyHoistedPhis();
simplifyConditions();
Expand Down