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Fix dominator info update to accommodate CFG changes. 

This fixes PR1559.

llvm-svn: 40024
This commit is contained in:
Devang Patel 2007-07-18 23:48:20 +00:00
parent 86dff8f8be
commit bb8ea8cefc
1 changed files with 65 additions and 17 deletions
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80
llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
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@ -408,26 +408,70 @@ static inline void RemapInstruction(Instruction *I,
}
// CloneDomInfo - NewBB is cloned from Orig basic block. Now clone Dominator Info.
// If Orig is in Loop then find and use Orig dominator's cloned block as NewBB
// dominator.
void CloneDomInfo(BasicBlock *NewBB, BasicBlock *Orig, Loop *L,
//
// If Orig block's immediate dominator is mapped in VM then use corresponding
// immediate dominator from the map. Otherwise Orig block's dominator is also
// NewBB's dominator.
//
// OrigPreheader is loop pre-header before this patch started
// updating CFG. NewPrehader is loops new pre-header. However, after CFG
// manipulation, loop L may not exist. So rely in input parameter NewPreheader.
void CloneDomInfo(BasicBlock *NewBB, BasicBlock *Orig,
BasicBlock *NewPreheader, BasicBlock *OrigPreheader,
BasicBlock *OrigHeader,
DominatorTree *DT, DominanceFrontier *DF,
DenseMap<const Value*, Value*> &VM) {
// If NewBB alreay has found its place in domiantor tree then no need to do
// anything.
if (DT->getNode(NewBB))
return;
// If Orig does not have any immediate domiantor then its clone, NewBB, does
// not need any immediate dominator.
DomTreeNode *OrigNode = DT->getNode(Orig);
if (!OrigNode)
return;
BasicBlock *OrigIDom = OrigNode->getBlock();
DomTreeNode *OrigIDomNode = OrigNode->getIDom();
if (!OrigIDomNode)
return;
BasicBlock *OrigIDom = NULL;
// If Orig is original loop header then its immediate dominator is
// NewPreheader.
if (Orig == OrigHeader)
OrigIDom = NewPreheader;
// If Orig is new pre-header then its immediate dominator is
// original pre-header.
else if (Orig == NewPreheader)
OrigIDom = OrigPreheader;
// Other as DT to find Orig's immediate dominator.
else
OrigIDom = OrigIDomNode->getBlock();
// Initially use Orig's immediate dominator as NewBB's immediate dominator.
BasicBlock *NewIDom = OrigIDom;
if (L->contains(OrigIDom)) {
if (!DT->getNode(OrigIDom))
CloneDomInfo(NewIDom, OrigIDom, L, DT, DF, VM);
NewIDom = cast<BasicBlock>(VM[OrigIDom]);
DenseMap<const Value*, Value*>::iterator I = VM.find(OrigIDom);
if (I != VM.end()) {
// if (!DT->getNode(OrigIDom))
// CloneDomInfo(NewIDom, OrigIDom, NewPreheader, OrigPreheader,
// OrigHeader, DT, DF, VM);
NewIDom = cast<BasicBlock>(I->second);
// If NewIDom does not have corresponding dominatore tree node then
// get one.
if (!DT->getNode(NewIDom))
CloneDomInfo(NewIDom, OrigIDom, NewPreheader, OrigPreheader,
OrigHeader, DT, DF, VM);
}
if (NewBB == NewIDom) {
DT->addNewBlock(NewBB, OrigIDom);
DT->changeImmediateDominator(NewBB, NewIDom);
} else
// if (NewBB == NewIDom) {
// DT->addNewBlock(NewBB, OrigIDom);
// DT->changeImmediateDominator(NewBB, NewIDom);
//} else
DT->addNewBlock(NewBB, NewIDom);
DominanceFrontier::DomSetType NewDFSet;
@ -438,8 +482,9 @@ void CloneDomInfo(BasicBlock *NewBB, BasicBlock *Orig, Loop *L,
for (DominanceFrontier::DomSetType::iterator I = S.begin(), E = S.end();
I != E; ++I) {
BasicBlock *BB = *I;
if (L->contains(BB))
NewDFSet.insert(cast<BasicBlock>(VM[Orig]));
DenseMap<const Value*, Value*>::iterator I = VM.find(BB);
if (I != VM.end())
NewDFSet.insert(cast<BasicBlock>(I->second));
else
NewDFSet.insert(BB);
}
@ -564,8 +609,10 @@ void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
// First step, split the preheader and exit blocks, and add these blocks to
// the LoopBlocks list.
BasicBlock *OrigHeader = L->getHeader();
BasicBlock *OrigPreheader = L->getLoopPreheader();
LoopBlocks.push_back(SplitEdge(OrigPreheader, L->getHeader(), this));
BasicBlock *NewPreheader = SplitEdge(OrigPreheader, L->getHeader(), this);
LoopBlocks.push_back(NewPreheader);
// We want the loop to come after the preheader, but before the exit blocks.
LoopBlocks.insert(LoopBlocks.end(), L->block_begin(), L->block_end());
@ -643,7 +690,8 @@ void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
for (unsigned i = 0, e = LoopBlocks.size(); i != e; ++i) {
BasicBlock *LBB = LoopBlocks[i];
BasicBlock *NBB = NewBlocks[i];
CloneDomInfo(NBB, LBB, L, DT, DF, ValueMap);
CloneDomInfo(NBB, LBB, NewPreheader, OrigPreheader,
OrigHeader, DT, DF, ValueMap);
}
// Splice the newly inserted blocks into the function right before the