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Fix LoopSimplify/2004-04-13-LoopSimplifyUpdateDomFrontier.ll

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LoopSimplify was not updating dominator frontiers correctly in some cases.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12890 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-04-13 16:23:25 +00:00
parent 4acd51a1c1
commit 4b66242c54
1 changed files with 41 additions and 25 deletions
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66
lib/Transforms/Utils/LoopSimplify.cpp
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@ -509,7 +509,6 @@ static PHINode *FindPHIToPartitionLoops(Loop *L) {
/// created.
///
Loop *LoopSimplify::SeparateNestedLoop(Loop *L) {
BasicBlock *Header = L->getHeader();
PHINode *PN = FindPHIToPartitionLoops(L);
if (PN == 0) return 0; // No known way to partition.
@ -522,6 +521,7 @@ Loop *LoopSimplify::SeparateNestedLoop(Loop *L) {
!L->contains(PN->getIncomingBlock(i)))
OuterLoopPreds.push_back(PN->getIncomingBlock(i));
BasicBlock *Header = L->getHeader();
BasicBlock *NewBB = SplitBlockPredecessors(Header, ".outer", OuterLoopPreds);
// Update dominator information (set, immdom, domtree, and domfrontier)
@ -830,9 +830,9 @@ void LoopSimplify::UpdateDomInfoForRevectoredPreds(BasicBlock *NewBB,
// Update dominance frontier information...
if (DominanceFrontier *DF = getAnalysisToUpdate<DominanceFrontier>()) {
// If NewBB dominates NewBBSucc, then the global dominance frontiers are not
// changed. DF(NewBB) is now going to be the DF(PredBlocks[0]) without the
// stuff that the new block does not dominate a predecessor of.
// If NewBB dominates NewBBSucc, then DF(NewBB) is now going to be the
// DF(PredBlocks[0]) without the stuff that the new block does not dominate
// a predecessor of.
if (NewBBDominatesNewBBSucc) {
DominanceFrontier::iterator DFI = DF->find(PredBlocks[0]);
if (DFI != DF->end()) {
@ -861,29 +861,45 @@ void LoopSimplify::UpdateDomInfoForRevectoredPreds(BasicBlock *NewBB,
DominanceFrontier::DomSetType NewDFSet;
NewDFSet.insert(NewBBSucc);
DF->addBasicBlock(NewBB, NewDFSet);
// Now we must loop over all of the dominance frontiers in the function,
// replacing occurrences of NewBBSucc with NewBB in some cases. All
// blocks that dominate a block in PredBlocks and contained NewBBSucc in
// their dominance frontier must be updated to contain NewBB instead.
//
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);
for (DominatorSet::DomSetType::const_iterator PDI = PredDoms.begin(),
PDE = PredDoms.end(); PDI != PDE; ++PDI) {
BasicBlock *PredDom = *PDI;
}
// If the NewBBSucc node is in DF(PredDom), then PredDom didn't
// dominate NewBBSucc but did dominate a predecessor of it. Now we
// change this entry to include NewBB in the DF instead of NewBBSucc.
DominanceFrontier::iterator DFI = DF->find(PredDom);
assert(DFI != DF->end() && "No dominance frontier for node?");
if (DFI->second.count(NewBBSucc)) {
DF->removeFromFrontier(DFI, NewBBSucc);
DF->addToFrontier(DFI, NewBB);
// Now we must loop over all of the dominance frontiers in the function,
// replacing occurrences of NewBBSucc with NewBB in some cases. All
// blocks that dominate a block in PredBlocks and contained NewBBSucc in
// their dominance frontier must be updated to contain NewBB instead.
//
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);
for (DominatorSet::DomSetType::const_iterator PDI = PredDoms.begin(),
PDE = PredDoms.end(); PDI != PDE; ++PDI) {
BasicBlock *PredDom = *PDI;
// If the NewBBSucc node is in DF(PredDom), then PredDom didn't
// dominate NewBBSucc but did dominate a predecessor of it. Now we
// change this entry to include NewBB in the DF instead of NewBBSucc.
DominanceFrontier::iterator DFI = DF->find(PredDom);
assert(DFI != DF->end() && "No dominance frontier for node?");
if (DFI->second.count(NewBBSucc)) {
// If NewBBSucc should not stay in our dominator frontier, remove it.
// We remove it unless there is a predecessor of NewBBSucc that we
// dominate, but we don't strictly dominate NewBBSucc.
bool ShouldRemove = true;
if (PredDom == NewBBSucc || !DS.dominates(PredDom, NewBBSucc)) {
// Okay, we know that PredDom does not strictly dominate NewBBSucc.
// Check to see if it dominates any predecessors of NewBBSucc.
for (pred_iterator PI = pred_begin(NewBBSucc),
E = pred_end(NewBBSucc); PI != E; ++PI)
if (DS.dominates(PredDom, *PI)) {
ShouldRemove = false;
break;
}
}
if (ShouldRemove)
DF->removeFromFrontier(DFI, NewBBSucc);
DF->addToFrontier(DFI, NewBB);
}
}
}