/// CloneDominatorInfo - Clone basicblock's dominator tree and, if available,
/// dominance info. It is expected that basic block is already cloned.
static void CloneDominatorInfo(BasicBlock *BB,
DenseMap<const Value *, Value *> &ValueMap,
DominatorTree *DT,
DominanceFrontier *DF) {
assert (DT && "DominatorTree is not available");
DenseMap<const Value *, Value*>::iterator BI = ValueMap.find(BB);
assert (BI != ValueMap.end() && "BasicBlock clone is missing");
BasicBlock *NewBB = cast<BasicBlock>(BI->second);
// NewBB already got dominator info.
if (DT->getNode(NewBB))
return;
assert (DT->getNode(BB) && "BasicBlock does not have dominator info");
// Entry block is not expected here. Infinite loops are not to cloned.
assert (DT->getNode(BB)->getIDom() && "BasicBlock does not have immediate dominator");
BasicBlock *BBDom = DT->getNode(BB)->getIDom()->getBlock();
// NewBB's dominator is either BB's dominator or BB's dominator's clone.
BasicBlock *NewBBDom = BBDom;
DenseMap<const Value *, Value*>::iterator BBDomI = ValueMap.find(BBDom);
if (BBDomI != ValueMap.end()) {
NewBBDom = cast<BasicBlock>(BBDomI->second);
if (!DT->getNode(NewBBDom))
CloneDominatorInfo(BBDom, ValueMap, DT, DF);
}
DT->addNewBlock(NewBB, NewBBDom);
// Copy cloned dominance frontiner set
if (DF) {
DominanceFrontier::DomSetType NewDFSet;
DominanceFrontier::iterator DFI = DF->find(BB);
if ( DFI != DF->end()) {
DominanceFrontier::DomSetType S = DFI->second;
for (DominanceFrontier::DomSetType::iterator I = S.begin(), E = S.end();
I != E; ++I) {
BasicBlock *DB = *I;
DenseMap<const Value*, Value*>::iterator IDM = ValueMap.find(DB);
if (IDM != ValueMap.end())
NewDFSet.insert(cast<BasicBlock>(IDM->second));
else
NewDFSet.insert(DB);
}
}
DF->addBasicBlock(NewBB, NewDFSet);
}
}
// NewBB is split and now it has one successor. Update dominace frontier to
// reflect this change.
void DominanceFrontier::splitBlock(BasicBlock *NewBB) {
assert(NewBB->getTerminator()->getNumSuccessors() == 1
&& "NewBB should have a single successor!");
BasicBlock *NewBBSucc = NewBB->getTerminator()->getSuccessor(0);
SmallVector<BasicBlock*, 8> PredBlocks;
for (pred_iterator PI = pred_begin(NewBB), PE = pred_end(NewBB);
PI != PE; ++PI)
PredBlocks.push_back(*PI);
if (PredBlocks.empty())
// If NewBB does not have any predecessors then it is a entry block.
// In this case, NewBB and its successor NewBBSucc dominates all
// other blocks.
return;
// NewBBSucc inherits original NewBB frontier.
DominanceFrontier::iterator NewBBI = find(NewBB);
if (NewBBI != end()) {
DominanceFrontier::DomSetType NewBBSet = NewBBI->second;
DominanceFrontier::DomSetType NewBBSuccSet;
NewBBSuccSet.insert(NewBBSet.begin(), NewBBSet.end());
addBasicBlock(NewBBSucc, NewBBSuccSet);
}
// 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.
DominatorTree &DT = getAnalysis<DominatorTree>();
if (DT.dominates(NewBB, NewBBSucc)) {
DominanceFrontier::iterator DFI = find(PredBlocks[0]);
if (DFI != end()) {
DominanceFrontier::DomSetType Set = DFI->second;
// Filter out stuff in Set that we do not dominate a predecessor of.
for (DominanceFrontier::DomSetType::iterator SetI = Set.begin(),
E = Set.end(); SetI != E;) {
bool DominatesPred = false;
for (pred_iterator PI = pred_begin(*SetI), E = pred_end(*SetI);
PI != E; ++PI)
if (DT.dominates(NewBB, *PI))
DominatesPred = true;
if (!DominatesPred)
Set.erase(SetI++);
else
++SetI;
}
if (NewBBI != end()) {
for (DominanceFrontier::DomSetType::iterator SetI = Set.begin(),
E = Set.end(); SetI != E; ++SetI) {
BasicBlock *SB = *SetI;
addToFrontier(NewBBI, SB);
}
} else
addBasicBlock(NewBB, Set);
}
} else {
// DF(NewBB) is {NewBBSucc} because NewBB does not strictly dominate
// NewBBSucc, but it does dominate itself (and there is an edge (NewBB ->
// NewBBSucc)). NewBBSucc is the single successor of NewBB.
DominanceFrontier::DomSetType NewDFSet;
NewDFSet.insert(NewBBSucc);
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 (Function::iterator FI = NewBB->getParent()->begin(),
FE = NewBB->getParent()->end(); FI != FE; ++FI) {
DominanceFrontier::iterator DFI = find(FI);
if (DFI == end()) continue; // unreachable block.
// Only consider nodes that have NewBBSucc in their dominator frontier.
if (!DFI->second.count(NewBBSucc)) continue;
// Verify whether this block dominates a block in predblocks. If not, do
// not update it.
bool BlockDominatesAny = false;
for (SmallVectorImpl<BasicBlock*>::const_iterator BI = PredBlocks.begin(),
BE = PredBlocks.end(); BI != BE; ++BI) {
if (DT.dominates(FI, *BI)) {
BlockDominatesAny = true;
break;
}
}
// 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 ((BasicBlock*)FI == NewBBSucc || !DT.dominates(FI, 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 (DT.dominates(FI, *PI)) {
ShouldRemove = false;
break;
}
}
if (ShouldRemove)
removeFromFrontier(DFI, NewBBSucc);
if (BlockDominatesAny && (&*FI == NewBB || !DT.dominates(FI, NewBB)))
addToFrontier(DFI, NewBB);
}
}
/// removeBlocks - Remove basic block DeadBB and all blocks dominated by DeadBB.
/// This routine is used to remove split condition's dead branch, dominated by
/// DeadBB. LiveBB dominates split conidition's other branch.
void LoopIndexSplit::removeBlocks(BasicBlock *DeadBB, Loop *LP,
BasicBlock *LiveBB) {
// First update DeadBB's dominance frontier.
SmallVector<BasicBlock *, 8> FrontierBBs;
DominanceFrontier::iterator DeadBBDF = DF->find(DeadBB);
if (DeadBBDF != DF->end()) {
SmallVector<BasicBlock *, 8> PredBlocks;
DominanceFrontier::DomSetType DeadBBSet = DeadBBDF->second;
for (DominanceFrontier::DomSetType::iterator DeadBBSetI = DeadBBSet.begin(),
DeadBBSetE = DeadBBSet.end(); DeadBBSetI != DeadBBSetE; ++DeadBBSetI)
{
BasicBlock *FrontierBB = *DeadBBSetI;
FrontierBBs.push_back(FrontierBB);
// Rremove any PHI incoming edge from blocks dominated by DeadBB.
PredBlocks.clear();
for(pred_iterator PI = pred_begin(FrontierBB), PE = pred_end(FrontierBB);
PI != PE; ++PI) {
BasicBlock *P = *PI;
if (P == DeadBB || DT->dominates(DeadBB, P))
PredBlocks.push_back(P);
}
for(BasicBlock::iterator FBI = FrontierBB->begin(), FBE = FrontierBB->end();
FBI != FBE; ++FBI) {
if (PHINode *PN = dyn_cast<PHINode>(FBI)) {
for(SmallVector<BasicBlock *, 8>::iterator PI = PredBlocks.begin(),
PE = PredBlocks.end(); PI != PE; ++PI) {
BasicBlock *P = *PI;
PN->removeIncomingValue(P);
}
}
else
break;
}
}
}
// Now remove DeadBB and all nodes dominated by DeadBB in df order.
SmallVector<BasicBlock *, 32> WorkList;
DomTreeNode *DN = DT->getNode(DeadBB);
for (df_iterator<DomTreeNode*> DI = df_begin(DN),
E = df_end(DN); DI != E; ++DI) {
BasicBlock *BB = DI->getBlock();
WorkList.push_back(BB);
BB->replaceAllUsesWith(UndefValue::get(
Type::getLabelTy(DeadBB->getContext())));
}
while (!WorkList.empty()) {
BasicBlock *BB = WorkList.back(); WorkList.pop_back();
LPM->deleteSimpleAnalysisValue(BB, LP);
for(BasicBlock::iterator BBI = BB->begin(), BBE = BB->end();
BBI != BBE; ) {
Instruction *I = BBI;
++BBI;
I->replaceAllUsesWith(UndefValue::get(I->getType()));
LPM->deleteSimpleAnalysisValue(I, LP);
I->eraseFromParent();
}
DT->eraseNode(BB);
DF->removeBlock(BB);
LI->removeBlock(BB);
BB->eraseFromParent();
}
// Update Frontier BBs' dominator info.
while (!FrontierBBs.empty()) {
BasicBlock *FBB = FrontierBBs.back(); FrontierBBs.pop_back();
BasicBlock *NewDominator = FBB->getSinglePredecessor();
if (!NewDominator) {
pred_iterator PI = pred_begin(FBB), PE = pred_end(FBB);
NewDominator = *PI;
++PI;
if (NewDominator != LiveBB) {
for(; PI != PE; ++PI) {
BasicBlock *P = *PI;
if (P == LiveBB) {
NewDominator = LiveBB;
break;
}
NewDominator = DT->findNearestCommonDominator(NewDominator, P);
}
}
}
assert (NewDominator && "Unable to fix dominator info.");
DT->changeImmediateDominator(FBB, NewDominator);
DF->changeImmediateDominator(FBB, NewDominator, DT);
}
}
// NewBB is split and now it has one successor. Update dominance frontier to
// reflect this change.
void DominanceFrontier::splitBlock(BasicBlock *NewBB) {
assert(NewBB->getTerminator()->getNumSuccessors() == 1 &&
"NewBB should have a single successor!");
BasicBlock *NewBBSucc = NewBB->getTerminator()->getSuccessor(0);
// NewBBSucc inherits original NewBB frontier.
DominanceFrontier::iterator NewBBI = find(NewBB);
if (NewBBI != end())
addBasicBlock(NewBBSucc, NewBBI->second);
// If NewBB dominates NewBBSucc, then DF(NewBB) is now going to be the
// DF(NewBBSucc) without the stuff that the new block does not dominate
// a predecessor of.
DominatorTree &DT = getAnalysis<DominatorTree>();
DomTreeNode *NewBBNode = DT.getNode(NewBB);
DomTreeNode *NewBBSuccNode = DT.getNode(NewBBSucc);
if (DT.dominates(NewBBNode, NewBBSuccNode)) {
DominanceFrontier::iterator DFI = find(NewBBSucc);
if (DFI != end()) {
DominanceFrontier::DomSetType Set = DFI->second;
// Filter out stuff in Set that we do not dominate a predecessor of.
for (DominanceFrontier::DomSetType::iterator SetI = Set.begin(),
E = Set.end(); SetI != E;) {
bool DominatesPred = false;
for (pred_iterator PI = pred_begin(*SetI), E = pred_end(*SetI);
PI != E; ++PI)
if (DT.dominates(NewBBNode, DT.getNode(*PI))) {
DominatesPred = true;
break;
}
if (!DominatesPred)
Set.erase(SetI++);
else
++SetI;
}
if (NewBBI != end()) {
for (DominanceFrontier::DomSetType::iterator SetI = Set.begin(),
E = Set.end(); SetI != E; ++SetI) {
BasicBlock *SB = *SetI;
addToFrontier(NewBBI, SB);
}
} else
addBasicBlock(NewBB, Set);
}
} else {
// DF(NewBB) is {NewBBSucc} because NewBB does not strictly dominate
// NewBBSucc, but it does dominate itself (and there is an edge (NewBB ->
// NewBBSucc)). NewBBSucc is the single successor of NewBB.
DominanceFrontier::DomSetType NewDFSet;
NewDFSet.insert(NewBBSucc);
addBasicBlock(NewBB, NewDFSet);
}
// Now update dominance frontiers which either used to contain NewBBSucc
// or which now need to include NewBB.
// Collect the set of blocks which dominate a predecessor of NewBB or
// NewSuccBB and which don't dominate both. This is an initial
// approximation of the blocks whose dominance frontiers will need updates.
SmallVector<DomTreeNode *, 16> AllPredDoms;
// Compute the block which dominates both NewBBSucc and NewBB. This is
// the immediate dominator of NewBBSucc unless NewBB dominates NewBBSucc.
// The code below which climbs dominator trees will stop at this point,
// because from this point up, dominance frontiers are unaffected.
DomTreeNode *DominatesBoth = 0;
if (NewBBSuccNode) {
DominatesBoth = NewBBSuccNode->getIDom();
if (DominatesBoth == NewBBNode)
DominatesBoth = NewBBNode->getIDom();
}
// Collect the set of all blocks which dominate a predecessor of NewBB.
SmallPtrSet<DomTreeNode *, 8> NewBBPredDoms;
for (pred_iterator PI = pred_begin(NewBB), E = pred_end(NewBB); PI != E; ++PI)
for (DomTreeNode *DTN = DT.getNode(*PI); DTN; DTN = DTN->getIDom()) {
if (DTN == DominatesBoth)
break;
if (!NewBBPredDoms.insert(DTN))
break;
AllPredDoms.push_back(DTN);
}
// Collect the set of all blocks which dominate a predecessor of NewSuccBB.
SmallPtrSet<DomTreeNode *, 8> NewBBSuccPredDoms;
for (pred_iterator PI = pred_begin(NewBBSucc),
E = pred_end(NewBBSucc); PI != E; ++PI)
for (DomTreeNode *DTN = DT.getNode(*PI); DTN; DTN = DTN->getIDom()) {
if (DTN == DominatesBoth)
break;
if (!NewBBSuccPredDoms.insert(DTN))
break;
if (!NewBBPredDoms.count(DTN))
AllPredDoms.push_back(DTN);
}
// Visit all relevant dominance frontiers and make any needed updates.
for (SmallVectorImpl<DomTreeNode *>::const_iterator I = AllPredDoms.begin(),
E = AllPredDoms.end(); I != E; ++I) {
DomTreeNode *DTN = *I;
iterator DFI = find((*I)->getBlock());
// Only consider nodes that have NewBBSucc in their dominator frontier.
if (DFI == end() || !DFI->second.count(NewBBSucc)) continue;
// If the block dominates a predecessor of NewBB but does not properly
// dominate NewBB itself, add NewBB to its dominance frontier.
if (NewBBPredDoms.count(DTN) &&
!DT.properlyDominates(DTN, NewBBNode))
addToFrontier(DFI, NewBB);
// If the block does not dominate a predecessor of NewBBSucc or
// properly dominates NewBBSucc itself, remove NewBBSucc from its
// dominance frontier.
if (!NewBBSuccPredDoms.count(DTN) ||
DT.properlyDominates(DTN, NewBBSuccNode))
removeFromFrontier(DFI, NewBBSucc);
}
}