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Fix PR932 and Analysis/Dominators/2006-10-02-BreakCritEdges.ll:
The critical edge block dominates the dest block if the destblock dominates all edges other than the one incoming from the critical edge. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30696 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -25,6 +25,7 @@
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#include "llvm/Type.h"
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#include "llvm/Support/CFG.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/Statistic.h"
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using namespace llvm;
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@ -135,10 +136,21 @@ bool llvm::SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum, Pass *P) {
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// If we don't have a pass object, we can't update anything...
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if (P == 0) return true;
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// Now update analysis information. These are the analyses that we are
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// currently capable of updating...
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//
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// Now update analysis information. Since the only predecessor of NewBB is
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// the TIBB, TIBB clearly dominates NewBB. TIBB usually doesn't dominate
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// anything, as there are other successors of DestBB. However, if all other
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// predecessors of DestBB are already dominated by DestBB (e.g. DestBB is a
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// loop header) then NewBB dominates DestBB.
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SmallVector<BasicBlock*, 8> OtherPreds;
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for (pred_iterator I = pred_begin(DestBB), E = pred_end(DestBB); I != E; ++I)
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if (*I != NewBB)
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OtherPreds.push_back(*I);
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// NewBBDominatesDestBB is valid if OtherPreds is empty, otherwise it isn't
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// yet computed.
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bool NewBBDominatesDestBB = true;
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// Should we update DominatorSet information?
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if (DominatorSet *DS = P->getAnalysisToUpdate<DominatorSet>()) {
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// The blocks that dominate the new one are the blocks that dominate TIBB
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@ -146,18 +158,65 @@ bool llvm::SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum, Pass *P) {
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DominatorSet::DomSetType DomSet = DS->getDominators(TIBB);
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DomSet.insert(NewBB); // A block always dominates itself.
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DS->addBasicBlock(NewBB, DomSet);
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// If NewBBDominatesDestBB hasn't been computed yet, do so with DS.
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if (!OtherPreds.empty()) {
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while (!OtherPreds.empty() && NewBBDominatesDestBB) {
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NewBBDominatesDestBB = DS->dominates(DestBB, OtherPreds.back());
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OtherPreds.pop_back();
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}
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OtherPreds.clear();
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}
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// If NewBBDominatesDestBB, then NewBB dominates DestBB, otherwise it
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// doesn't dominate anything. If NewBB does dominates DestBB, then it
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// dominates everything that DestBB dominates.
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if (NewBBDominatesDestBB) {
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for (DominatorSet::iterator I = DS->begin(), E = DS->end(); I != E; ++I)
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if (I->second.count(DestBB))
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I->second.insert(NewBB);
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}
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}
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// Should we update ImmediateDominator information?
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if (ImmediateDominators *ID = P->getAnalysisToUpdate<ImmediateDominators>()) {
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// TIBB is the new immediate dominator for NewBB. NewBB doesn't dominate
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// anything.
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// TIBB is the new immediate dominator for NewBB.
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ID->addNewBlock(NewBB, TIBB);
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// If NewBBDominatesDestBB hasn't been computed yet, do so with ID.
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if (!OtherPreds.empty()) {
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while (!OtherPreds.empty() && NewBBDominatesDestBB) {
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NewBBDominatesDestBB = ID->dominates(DestBB, OtherPreds.back());
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OtherPreds.pop_back();
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}
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OtherPreds.clear();
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}
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// If NewBBDominatesDestBB, then NewBB dominates DestBB, otherwise it
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// doesn't dominate anything.
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if (NewBBDominatesDestBB)
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ID->setImmediateDominator(DestBB, NewBB);
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}
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// Update the forest?
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if (ETForest *EF = P->getAnalysisToUpdate<ETForest>())
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if (ETForest *EF = P->getAnalysisToUpdate<ETForest>()) {
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// NewBB is dominated by TIBB.
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EF->addNewBlock(NewBB, TIBB);
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// If NewBBDominatesDestBB hasn't been computed yet, do so with EF.
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if (!OtherPreds.empty()) {
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while (!OtherPreds.empty() && NewBBDominatesDestBB) {
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NewBBDominatesDestBB = EF->dominates(DestBB, OtherPreds.back());
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OtherPreds.pop_back();
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}
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OtherPreds.clear();
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}
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// If NewBBDominatesDestBB, then NewBB dominates DestBB, otherwise it
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// doesn't dominate anything.
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if (NewBBDominatesDestBB)
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EF->setImmediateDominator(DestBB, NewBB);
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}
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// Should we update DominatorTree information?
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if (DominatorTree *DT = P->getAnalysisToUpdate<DominatorTree>()) {
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@ -166,18 +225,57 @@ bool llvm::SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum, Pass *P) {
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// The new block is not the immediate dominator for any other nodes, but
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// TINode is the immediate dominator for the new node.
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//
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if (TINode) // Don't break unreachable code!
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DT->createNewNode(NewBB, TINode);
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if (TINode) { // Don't break unreachable code!
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DominatorTree::Node *NewBBNode = DT->createNewNode(NewBB, TINode);
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DominatorTree::Node *DestBBNode = 0;
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// If NewBBDominatesDestBB hasn't been computed yet, do so with DT.
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if (!OtherPreds.empty()) {
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DestBBNode = DT->getNode(DestBB);
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while (!OtherPreds.empty() && NewBBDominatesDestBB) {
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if (DominatorTree::Node *OPNode = DT->getNode(OtherPreds.back()))
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NewBBDominatesDestBB = DestBBNode->dominates(OPNode);
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OtherPreds.pop_back();
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}
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OtherPreds.clear();
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}
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// If NewBBDominatesDestBB, then NewBB dominates DestBB, otherwise it
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// doesn't dominate anything.
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if (NewBBDominatesDestBB) {
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if (!DestBBNode) DestBBNode = DT->getNode(DestBB);
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DT->changeImmediateDominator(DestBBNode, NewBBNode);
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}
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}
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}
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// Should we update DominanceFrontier information?
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if (DominanceFrontier *DF = P->getAnalysisToUpdate<DominanceFrontier>()) {
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// If NewBBDominatesDestBB hasn't been computed yet, do so with DF.
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if (!OtherPreds.empty()) {
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#if 0
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// FIXME: IMPLEMENT THIS!
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OtherPreds.clear();
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#endif
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NewBBDominatesDestBB = false;
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}
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// Since the new block is dominated by its only predecessor TIBB,
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// it cannot be in any block's dominance frontier. Its dominance
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// frontier is {DestBB}.
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// it cannot be in any block's dominance frontier. If NewBB dominates
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// DestBB, its dominance frontier is the same as DestBB's, otherwise it is
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// just {DestBB}.
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DominanceFrontier::DomSetType NewDFSet;
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NewDFSet.insert(DestBB);
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DF->addBasicBlock(NewBB, NewDFSet);
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if (NewBBDominatesDestBB) {
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DominanceFrontier::iterator I = DF->find(DestBB);
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if (I != DF->end())
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DF->addBasicBlock(NewBB, I->second);
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else
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DF->addBasicBlock(NewBB, DominanceFrontier::DomSetType());
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} else {
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DominanceFrontier::DomSetType NewDFSet;
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NewDFSet.insert(DestBB);
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DF->addBasicBlock(NewBB, NewDFSet);
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}
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}
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// Update LoopInfo if it is around.
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@ -190,10 +288,10 @@ bool llvm::SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum, Pass *P) {
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// Both in the same loop, the NewBB joins loop.
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DestLoop->addBasicBlockToLoop(NewBB, *LI);
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} else if (TIL->contains(DestLoop->getHeader())) {
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// Edge from an outer loop to an inner loop. Add to the outer lopo.
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// Edge from an outer loop to an inner loop. Add to the outer loop.
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TIL->addBasicBlockToLoop(NewBB, *LI);
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} else if (DestLoop->contains(TIL->getHeader())) {
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// Edge from an inner loop to an outer loop. Add to the outer lopo.
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// Edge from an inner loop to an outer loop. Add to the outer loop.
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DestLoop->addBasicBlockToLoop(NewBB, *LI);
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} else {
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// Edge from two loops with no containment relation. Because these
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@ -206,7 +304,6 @@ bool llvm::SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum, Pass *P) {
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P->addBasicBlockToLoop(NewBB, *LI);
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}
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}
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}
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return true;
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}
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