} else if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
if (!Inserted.insert(U)) continue;
const Value *V = U->getValue();
- if (const Instruction *Inst = dyn_cast<Instruction>(V))
+ if (const Instruction *Inst = dyn_cast<Instruction>(V)) {
+ // Look for instructions defined outside the loop.
if (L->contains(Inst)) continue;
+ } else if (isa<UndefValue>(V))
+ // Undef doesn't have a live range, so it doesn't matter.
+ continue;
for (Value::const_use_iterator UI = V->use_begin(), UE = V->use_end();
UI != UE; ++UI) {
const Instruction *UserInst = dyn_cast<Instruction>(*UI);