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[SimplifyCFG] SimplifyEqualityComparisonWithOnlyPredecessor(): switch to non-permissive DomTree updates 

... which requires not deleting an edge that just got deleted.
This commit is contained in:
Roman Lebedev 2021-01-05 00:06:38 +03:00
parent a8604e3d5b
commit 110b3d7855
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GPG Key ID: 083C3EBB4A1689E0
1 changed files with 9 additions and 5 deletions
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14
llvm/lib/Transforms/Utils/SimplifyCFG.cpp
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@ -872,7 +872,6 @@ static void setBranchWeights(Instruction *I, uint32_t TrueWeight,
/// also a value comparison with the same value, and if that comparison
/// determines the outcome of this comparison. If so, simplify TI. This does a
/// very limited form of jump threading.
// FIXME: switch to non-permissive DomTreeUpdater::applyUpdates().
bool SimplifyCFGOpt::SimplifyEqualityComparisonWithOnlyPredecessor(
Instruction *TI, BasicBlock *Pred, IRBuilder<> &Builder) {
Value *PredVal = isValueEqualityComparison(Pred->getTerminator());
@ -988,14 +987,14 @@ bool SimplifyCFGOpt::SimplifyEqualityComparisonWithOnlyPredecessor(
if (!TheRealDest)
TheRealDest = ThisDef;
SmallVector<DominatorTree::UpdateType, 2> Updates;
SmallSetVector<BasicBlock *, 2> RemovedSuccs;
// Remove PHI node entries for dead edges.
BasicBlock *CheckEdge = TheRealDest;
for (BasicBlock *Succ : successors(TIBB))
if (Succ != CheckEdge) {
RemovedSuccs.insert(Succ);
Succ->removePredecessor(TIBB);
Updates.push_back({DominatorTree::Delete, TIBB, Succ});
} else
CheckEdge = nullptr;
@ -1008,8 +1007,13 @@ bool SimplifyCFGOpt::SimplifyEqualityComparisonWithOnlyPredecessor(
<< "\n");
EraseTerminatorAndDCECond(TI);
if (DTU)
DTU->applyUpdatesPermissive(Updates);
if (DTU) {
SmallVector<DominatorTree::UpdateType, 2> Updates;
Updates.reserve(RemovedSuccs.size());
for (auto *RemovedSucc : RemovedSuccs)
Updates.push_back({DominatorTree::Delete, TIBB, RemovedSucc});
DTU->applyUpdates(Updates);
}
return true;
}