// foo(a + b);
// if (p2)
// bar(a + b);
- DenseMap<const SCEV *, SmallVector<Instruction *, 2>> SeenExprs;
+ DenseMap<const SCEV *, SmallVector<WeakVH, 2>> SeenExprs;
};
} // anonymous namespace
Node != GraphTraits<DominatorTree *>::nodes_end(DT); ++Node) {
BasicBlock *BB = Node->getBlock();
for (auto I = BB->begin(); I != BB->end(); ++I) {
- if (SE->isSCEVable(I->getType()) && isPotentiallyNaryReassociable(I)) {
- const SCEV *OldSCEV = SE->getSCEV(I);
- if (Instruction *NewI = tryReassociate(I)) {
+ if (SE->isSCEVable(I->getType()) && isPotentiallyNaryReassociable(&*I)) {
+ const SCEV *OldSCEV = SE->getSCEV(&*I);
+ if (Instruction *NewI = tryReassociate(&*I)) {
Changed = true;
- SE->forgetValue(I);
+ SE->forgetValue(&*I);
I->replaceAllUsesWith(NewI);
- RecursivelyDeleteTriviallyDeadInstructions(I, TLI);
- I = NewI;
+ // If SeenExprs constains I's WeakVH, that entry will be replaced with
+ // nullptr.
+ RecursivelyDeleteTriviallyDeadInstructions(&*I, TLI);
+ I = NewI->getIterator();
}
// Add the rewritten instruction to SeenExprs; the original instruction
// is deleted.
- const SCEV *NewSCEV = SE->getSCEV(I);
- SeenExprs[NewSCEV].push_back(I);
+ const SCEV *NewSCEV = SE->getSCEV(&*I);
+ SeenExprs[NewSCEV].push_back(WeakVH(&*I));
// Ideally, NewSCEV should equal OldSCEV because tryReassociate(I)
// is equivalent to I. However, ScalarEvolution::getSCEV may
// weaken nsw causing NewSCEV not to equal OldSCEV. For example, suppose
//
// This improvement is exercised in @reassociate_gep_nsw in nary-gep.ll.
if (NewSCEV != OldSCEV)
- SeenExprs[OldSCEV].push_back(I);
+ SeenExprs[OldSCEV].push_back(WeakVH(&*I));
}
}
}
// future instruction either. Therefore, we pop it out of the stack. This
// optimization makes the algorithm O(n).
while (!Candidates.empty()) {
- Instruction *Candidate = Candidates.back();
- if (DT->dominates(Candidate, Dominatee))
- return Candidate;
+ // Candidates stores WeakVHs, so a candidate can be nullptr if it's removed
+ // during rewriting.
+ if (Value *Candidate = Candidates.back()) {
+ Instruction *CandidateInstruction = cast<Instruction>(Candidate);
+ if (DT->dominates(CandidateInstruction, Dominatee))
+ return CandidateInstruction;
+ }
Candidates.pop_back();
}
return nullptr;