> // Can we eliminate this phi node now?
> if (Value *V = PN->hasConstantValue(true)) {
> - if (!isa<Instruction>(V) ||
> - getAnalysis<DominatorSet>().dominates(cast<Instruction>
> (V), PN)) {
> + Instruction *I = dyn_cast<Instruction>(V);
> + if (!I || (I->getParent() != NewBB &&
> + getAnalysis<ETForest>().dominates(I, PN))) {
Please add a comment that describes what is going on here, this is
subtle/non-obvious.
> @@ -727,14 +700,16 @@
> bool NewBBDominatesNewBBSucc = true;
> {
> BasicBlock *OnePred = PredBlocks[0];
> - unsigned i, e = PredBlocks.size();
> - for (i = 1; !DS.isReachable(OnePred); ++i) {
> + unsigned i = 1, e = PredBlocks.size();
> + for (i = 1; !ETF.dominates(&OnePred->getParent()->getEntryBlock
> (), OnePred);
> + ++i) {
Please add a ETForest::isReachableFromEntry(x).
> @@ -885,8 +844,14 @@
> for (unsigned i = 0, e = PredBlocks.size(); i != e; ++i) {
> BasicBlock *Pred = PredBlocks[i];
> // Get all of the dominators of the predecessor...
> - const DominatorSet::DomSetType &PredDoms = DS.getDominators
> (Pred);
> + // FIXME: There's probably a better way to do this...
> + std::vector<BasicBlock*> PredDoms;
> + for (Function::iterator I = Pred->getParent()->begin(),
> + E = Pred->getParent()->end(); I != E; ++I)
> + if (ETF.dominates(&(*I), Pred))
> + PredDoms.push_back(I);
> +
> - for (DominatorSet::DomSetType::const_iterator PDI =
> PredDoms.begin(),
> + for (std::vector<BasicBlock*>::const_iterator PDI =
> PredDoms.begin(),
> PDE = PredDoms.end(); PDI != PDE; ++PDI) {
> BasicBlock *PredDom = *PDI;
This does need to be fixed, it is not very efficient. Minor things:
(&(*I)) -> (I).
I would suggest an approach like this, if it works:
foreach BB in function:
if (NewBBSucc is in DF(BB))
if (any BB dominates any of Preds)
.. inner check for 'shouldremove' etc ..
-Chris
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