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[InstCombine] Improve foldDeadPhiWeb compile time #158057

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Merged
merged 4 commits into from
Sep 15, 2025
Merged

[InstCombine] Improve foldDeadPhiWeb compile time #158057

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9a6bce6
[InstCombine] Improve `foldDeadPhiWeb` compile time
Enna1 Sep 10, 2025
e0d096f
clang format
Enna1 Sep 11, 2025
517bd7c
Merge branch 'main' into users/Enna1/perf/fold-dead-phi-web-opt-time
Enna1 Sep 11, 2025
f5657f2
fix...
Enna1 Sep 11, 2025
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15 changes: 8 additions & 7 deletions llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -60,17 +60,18 @@ bool InstCombinerImpl::foldDeadPhiWeb(PHINode &PN) {
SmallVector<PHINode *, 16> Stack;
SmallPtrSet<PHINode *, 16> Visited;
Stack.push_back(&PN);
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We should also add the initial phi node to the Visited set.

Visited.insert(&PN);
while (!Stack.empty()) {
PHINode *Phi = Stack.pop_back_val();
if (!Visited.insert(Phi).second)
continue;
// Early stop if the set of PHIs is large
if (Visited.size() == 16)
return false;
for (User *Use : Phi->users()) {
if (PHINode *PhiUse = dyn_cast<PHINode>(Use))
if (PHINode *PhiUse = dyn_cast<PHINode>(Use)) {
if (!Visited.insert(PhiUse).second)
continue;
// Early stop if the set of PHIs is large
if (Visited.size() >= 16)
return false;
Stack.push_back(PhiUse);
else
} else
return false;
}
}
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