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Fix major bugs in dominator set & tree information updating 

llvm-svn: 3975
This commit is contained in:
Chris Lattner 2002-09-29 21:41:38 +00:00
parent 85dd58c2cb
commit 03a9e15a9f
1 changed files with 9 additions and 6 deletions
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15
llvm/lib/Transforms/Scalar/LoopSimplify.cpp
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@ -153,14 +153,18 @@ void Preheaders::InsertPreheaderForLoop(Loop *L) {
// Update dominator information if it is around...
if (DominatorSet *DS = getAnalysisToUpdate<DominatorSet>()) {
// We need to add information about the fact that NewBB dominates Header.
DS->addDominator(Header, NewBB);
// The blocks that dominate NewBB are the blocks that dominate Header,
// minus Header, plus NewBB.
DominatorSet::DomSetType DomSet = DS->getDominators(Header);
DomSet.insert(NewBB); // We dominate ourself
DomSet.erase(Header); // Header does not dominate us...
DS->addBasicBlock(NewBB, DomSet);
// The newly created basic block dominates all nodes dominated by Header.
for (Function::iterator I = Header->getParent()->begin(),
E = Header->getParent()->end(); I != E; ++I)
if (DS->dominates(Header, I))
DS->addDominator(I, NewBB);
}
// Update immediate dominator information if we have it...
@ -178,11 +182,10 @@ void Preheaders::InsertPreheaderForLoop(Loop *L) {
// the old header.
//
DominatorTree::Node *HeaderNode = DT->getNode(Header);
DominatorTree::Node *PHNode = DT->createNewNode(NewBB, HeaderNode);
DominatorTree::Node *PHNode = DT->createNewNode(NewBB,
HeaderNode->getIDom());
// Change the header node so that PNHode is the new immediate dominator
DT->changeImmediateDominator(HeaderNode, PHNode);
}
}