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Preserve dominator info. 

llvm-svn: 41053
This commit is contained in:
Devang Patel 2007-08-13 22:13:24 +00:00
parent c0fa0c52b3
commit b8a41bb4f1
1 changed files with 48 additions and 34 deletions
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82
llvm/lib/Transforms/Scalar/LoopIndexSplit.cpp
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@ -121,6 +121,7 @@ namespace {
LoopInfo *LI;
ScalarEvolution *SE;
DominatorTree *DT;
DominanceFrontier *DF;
SmallVector<SplitInfo, 4> SplitData;
// Induction variable whose range is being split by this transformation.
@ -154,6 +155,7 @@ bool LoopIndexSplit::runOnLoop(Loop *IncomingLoop, LPPassManager &LPM_Ref) {
SE = &getAnalysis<ScalarEvolution>();
DT = &getAnalysis<DominatorTree>();
LI = &getAnalysis<LoopInfo>();
DF = getAnalysisToUpdate<DominanceFrontier>();
initialize();
@ -463,7 +465,7 @@ bool LoopIndexSplit::processOneIterationLoop(SplitInfo &SD) {
// Only CFG change done is to remove Latch to Header edge. This
// does not change dominator tree because Latch did not dominate
// Header.
if (DominanceFrontier *DF = getAnalysisToUpdate<DominanceFrontier>()) {
if (DF) {
DominanceFrontier::iterator HeaderDF = DF->find(Header);
if (HeaderDF != DF->end())
DF->removeFromFrontier(HeaderDF, Header);
@ -589,39 +591,49 @@ unsigned LoopIndexSplit::findSplitCost(Loop *L, SplitInfo &SD) {
/// removeBlocks - Remove basic block BB and all blocks dominated by BB.
void LoopIndexSplit::removeBlocks(BasicBlock *InBB) {
SmallVector<BasicBlock *, 8> WorkList;
WorkList.push_back(InBB);
SmallVector<std::pair<BasicBlock *, succ_iterator>, 8> WorkList;
WorkList.push_back(std::make_pair(InBB, succ_begin(InBB)));
while (!WorkList.empty()) {
BasicBlock *BB = WorkList.back(); WorkList.pop_back();
// First process all successor
for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI) {
BasicBlock *SuccBB = *SI;
if (DT->dominates(BB, SuccBB)) {
WorkList.push_back(SuccBB);
continue;
}
// If SuccBB is not dominated by BB then it is not removed, however remove
// any PHI incoming edge from BB.
for(BasicBlock::iterator SBI = SuccBB->begin(), SBE = SuccBB->end();
SBI != SBE; ++SBI) {
if (PHINode *PN = dyn_cast<PHINode>(SBI))
PN->removeIncomingValue(BB);
else
break;
}
}
BasicBlock *BB = WorkList.back(). first;
succ_iterator SIter =WorkList.back().second;
// Now delete BB;
for(BasicBlock::iterator BBI = BB->begin(), BBE = BB->end();
BBI != BBE; ++BBI) {
Instruction *I = BBI;
I->replaceAllUsesWith(UndefValue::get(I->getType()));
I->eraseFromParent();
// If all successor's are processed then remove this block.
if (SIter == succ_end(BB)) {
WorkList.pop_back();
for(BasicBlock::iterator BBI = BB->begin(), BBE = BB->end();
BBI != BBE; ++BBI) {
Instruction *I = BBI;
I->replaceAllUsesWith(UndefValue::get(I->getType()));
I->eraseFromParent();
}
DT->eraseNode(BB);
DF->removeBlock(BB);
LI->removeBlock(BB);
BB->eraseFromParent();
} else {
BasicBlock *SuccBB = *SIter;
++WorkList.back().second;
if (DT->dominates(BB, SuccBB)) {
WorkList.push_back(std::make_pair(SuccBB, succ_begin(SuccBB)));
continue;
} else {
// If SuccBB is not dominated by BB then it is not removed, however remove
// any PHI incoming edge from BB.
for(BasicBlock::iterator SBI = SuccBB->begin(), SBE = SuccBB->end();
SBI != SBE; ++SBI) {
if (PHINode *PN = dyn_cast<PHINode>(SBI))
PN->removeIncomingValue(BB);
else
break;
}
// If BB is not dominating SuccBB then SuccBB is in BB's dominance
// frontiner.
DominanceFrontier::iterator BBDF = DF->find(BB);
DF->removeFromFrontier(BBDF, SuccBB);
}
}
LI->removeBlock(BB);
BB->eraseFromParent();
}
}
@ -692,13 +704,17 @@ bool LoopIndexSplit::splitLoop(SplitInfo &SD) {
} else
ExitInsn->setSuccessor(1, FalseHeader);
if (DT) {
DT->changeImmediateDominator(FalseHeader, ExitBlock);
DT->changeImmediateDominator(ExitDest, cast<BasicBlock>(ValueMap[ExitBlock]));
}
assert (!L->contains(ExitDest) && " Unable to find exit edge destination");
//[*] Split Exit Edge.
SplitEdge(ExitBlock, FalseHeader, this);
//[*] Eliminate split condition's false branch from True loop.
// Update true loop dom info (FIXME).
BasicBlock *SplitBlock = SD.SplitCondition->getParent();
BranchInst *BR = cast<BranchInst>(SplitBlock->getTerminator());
BasicBlock *FBB = BR->getSuccessor(1);
@ -709,14 +725,12 @@ bool LoopIndexSplit::splitLoop(SplitInfo &SD) {
ExitCondition->setOperand(ExitValueNum, TLExitValue);
//[*] Eliminate split condition's true branch in False loop CFG.
// Update false loop dom info (FXME).
BasicBlock *FSplitBlock = cast<BasicBlock>(ValueMap[SplitBlock]);
BranchInst *FBR = cast<BranchInst>(FSplitBlock->getTerminator());
BasicBlock *TBB = FBR->getSuccessor(0);
FBR->setUnconditionalDest(FBR->getSuccessor(1));
removeBlocks(TBB);
//[*] Update dom info in general (FIXME).
return true;
}