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

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... which requires not deleting an edge that just got deleted.
This commit is contained in:
Roman Lebedev 2021-01-04 23:13:07 +03:00
parent 3715f53732
commit 435c195959
1 changed files with 9 additions and 6 deletions
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15
lib/Transforms/Utils/SimplifyCFG.cpp
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@ -6218,19 +6218,18 @@ bool SimplifyCFGOpt::simplifySwitch(SwitchInst *SI, IRBuilder<> &Builder) {
return false;
}
// FIXME: switch to non-permissive DomTreeUpdater::applyUpdates().
bool SimplifyCFGOpt::simplifyIndirectBr(IndirectBrInst *IBI) {
BasicBlock *BB = IBI->getParent();
bool Changed = false;
// Eliminate redundant destinations.
std::vector<DominatorTree::UpdateType> Updates;
SmallPtrSet<Value *, 8> Succs;
SmallSetVector<BasicBlock *, 8> RemovedSuccs;
for (unsigned i = 0, e = IBI->getNumDestinations(); i != e; ++i) {
BasicBlock *Dest = IBI->getDestination(i);
if (!Dest->hasAddressTaken() || !Succs.insert(Dest).second) {
if (!Dest->hasAddressTaken())
Updates.push_back({DominatorTree::Delete, BB, Dest});
RemovedSuccs.insert(Dest);
Dest->removePredecessor(BB);
IBI->removeDestination(i);
--i;
@ -6239,9 +6238,13 @@ bool SimplifyCFGOpt::simplifyIndirectBr(IndirectBrInst *IBI) {
}
}
if (DTU)
DTU->applyUpdatesPermissive(Updates);
Updates.clear();
if (DTU) {
std::vector<DominatorTree::UpdateType> Updates;
Updates.reserve(RemovedSuccs.size());
for (auto *RemovedSucc : RemovedSuccs)
Updates.push_back({DominatorTree::Delete, BB, RemovedSucc});
DTU->applyUpdates(Updates);
}
if (IBI->getNumDestinations() == 0) {
// If the indirectbr has no successors, change it to unreachable.