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Preserve dom info while simplifing loop after the unswitch. 

llvm-svn: 53052
This commit is contained in:
Devang Patel 2008-07-02 22:58:54 +00:00
parent 30f1d3f0db
commit 5adfcb5783
1 changed files with 32 additions and 2 deletions
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34
llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
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@ -757,6 +757,22 @@ void LoopUnswitch::SplitExitEdges(Loop *L,
}
/// addBBToDomFrontier - Helper function. Insert DFBB in Basic Block BB's
/// dominance frontier using iterator DFI.
static void addBBToDomFrontier(DominanceFrontier &DF,
DominanceFrontier::iterator &DFI,
BasicBlock *BB, BasicBlock *DFBB) {
if (DFI != DF.end()) {
DF.addToFrontier(DFI, DFBB);
return;
}
DominanceFrontier::DomSetType NSet;
NSet.insert(DFBB);
DF.addBasicBlock(BB, NSet);
DFI = DF.find(BB);
}
/// UnswitchNontrivialCondition - We determined that the loop is profitable
/// to unswitch when LIC equal Val. Split it into loop versions and test the
/// condition outside of either loop. Return the loops created as Out1/Out2.
@ -1188,18 +1204,32 @@ void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC,
// trying to update it is complicated. So instead we preserve the
// loop structure and put the block on an dead code path.
BasicBlock *SISucc = SI->getSuccessor(i);
BasicBlock* Old = SI->getParent();
BasicBlock* Split = SplitBlock(Old, SI, this);
Instruction* OldTerm = Old->getTerminator();
BranchInst::Create(Split, SI->getSuccessor(i),
BranchInst::Create(Split, SISucc,
ConstantInt::getTrue(), OldTerm);
if (DT) {
// Now, SISucc is dominated by Old.
DT->changeImmediateDominator(SISucc, Old);
if (DF) {
// Now, Split does not dominate SISucc.
// SISucc is the only member in Split's DF.
DominanceFrontier::iterator S_DFI = DF->find(Split);
if (S_DFI != DF->end())
S_DFI->second.clear();
addBBToDomFrontier(*DF, S_DFI, Split, SISucc);
}
}
LPM->deleteSimpleAnalysisValue(Old->getTerminator(), L);
Old->getTerminator()->eraseFromParent();
PHINode *PN;
for (BasicBlock::iterator II = SI->getSuccessor(i)->begin();
for (BasicBlock::iterator II = SISucc->begin();
(PN = dyn_cast<PHINode>(II)); ++II) {
Value *InVal = PN->removeIncomingValue(Split, false);
PN->addIncoming(InVal, Old);