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Update dominator info for the middle blocks created while spliting
exit edge to preserve LCSSA. Fix dominance frontier update during loop unswitch. This fixes PR 1589. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40695 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -543,17 +543,8 @@ void LoopUnswitch::EmitPreheaderBranchOnCondition(Value *LIC, Constant *Val,
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std::swap(TrueDest, FalseDest);
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// Insert the new branch.
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BranchInst *BRI = new BranchInst(TrueDest, FalseDest, BranchVal, InsertPt);
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new BranchInst(TrueDest, FalseDest, BranchVal, InsertPt);
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// Update dominator info.
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// BranchVal is a new preheader so it dominates true and false destination
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// loop headers.
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if (DominatorTree *DT = getAnalysisToUpdate<DominatorTree>()) {
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DT->changeImmediateDominator(TrueDest, BRI->getParent());
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DT->changeImmediateDominator(FalseDest, BRI->getParent());
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}
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// No need to update DominanceFrontier. BRI->getParent() dominated TrueDest
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// and FalseDest anyway. Now it immediately dominates them.
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}
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@ -635,12 +626,14 @@ void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
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// Split all of the edges from inside the loop to their exit blocks. Update
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// the appropriate Phi nodes as we do so.
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SmallVector<BasicBlock *,8> MiddleBlocks;
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for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) {
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BasicBlock *ExitBlock = ExitBlocks[i];
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std::vector<BasicBlock*> Preds(pred_begin(ExitBlock), pred_end(ExitBlock));
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for (unsigned j = 0, e = Preds.size(); j != e; ++j) {
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BasicBlock* MiddleBlock = SplitEdge(Preds[j], ExitBlock, this);
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MiddleBlocks.push_back(MiddleBlock);
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BasicBlock* StartBlock = Preds[j];
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BasicBlock* EndBlock;
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if (MiddleBlock->getSinglePredecessor() == ExitBlock) {
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@ -685,6 +678,9 @@ void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
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// Add exit blocks to the loop blocks.
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LoopBlocks.insert(LoopBlocks.end(), ExitBlocks.begin(), ExitBlocks.end());
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DominanceFrontier *DF = getAnalysisToUpdate<DominanceFrontier>();
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DominatorTree *DT = getAnalysisToUpdate<DominatorTree>();
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// Next step, clone all of the basic blocks that make up the loop (including
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// the loop preheader and exit blocks), keeping track of the mapping between
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// the instructions and blocks.
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@ -698,16 +694,21 @@ void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
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LPM->cloneBasicBlockSimpleAnalysis(LoopBlocks[i], New, L);
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}
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// Update dominator info
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DominanceFrontier *DF = getAnalysisToUpdate<DominanceFrontier>();
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if (DominatorTree *DT = getAnalysisToUpdate<DominatorTree>())
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for (unsigned i = 0, e = LoopBlocks.size(); i != e; ++i) {
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BasicBlock *LBB = LoopBlocks[i];
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BasicBlock *NBB = NewBlocks[i];
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CloneDomInfo(NBB, LBB, NewPreheader, OrigPreheader,
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OrigHeader, DT, DF, ValueMap);
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// OutSiders are basic block that are dominated by original header and
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// at the same time they are not part of loop.
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SmallPtrSet<BasicBlock *, 8> OutSiders;
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if (DT) {
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DomTreeNode *OrigHeaderNode = DT->getNode(OrigHeader);
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for(std::vector<DomTreeNode*>::iterator DI = OrigHeaderNode->begin(),
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DE = OrigHeaderNode->end(); DI != DE; ++DI) {
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BasicBlock *B = (*DI)->getBlock();
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DenseMap<const Value*, Value*>::iterator VI = ValueMap.find(B);
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if (VI == ValueMap.end())
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OutSiders.insert(B);
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}
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}
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// Splice the newly inserted blocks into the function right before the
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// original preheader.
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F->getBasicBlockList().splice(LoopBlocks[0], F->getBasicBlockList(),
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@ -759,7 +760,61 @@ void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
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EmitPreheaderBranchOnCondition(LIC, Val, NewBlocks[0], LoopBlocks[0], OldBR);
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OldBR->eraseFromParent();
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LPM->deleteSimpleAnalysisValue(OldBR, L);
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// Update dominator info
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if (DF && DT) {
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// Clone dominator info for all cloned basic block.
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for (unsigned i = 0, e = LoopBlocks.size(); i != e; ++i) {
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BasicBlock *LBB = LoopBlocks[i];
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BasicBlock *NBB = NewBlocks[i];
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CloneDomInfo(NBB, LBB, NewPreheader, OrigPreheader,
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OrigHeader, DT, DF, ValueMap);
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// Remove any OutSiders from LBB and NBB's dominance frontier.
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DominanceFrontier::iterator LBBI = DF->find(LBB);
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if (LBBI != DF->end()) {
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DominanceFrontier::DomSetType &LBSet = LBBI->second;
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for (DominanceFrontier::DomSetType::iterator LI = LBSet.begin(),
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LE = LBSet.end(); LI != LE; ++LI) {
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BasicBlock *B = *LI;
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if (OutSiders.count(B))
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DF->removeFromFrontier(LBBI, B);
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}
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}
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// Remove any OutSiders from LBB and NBB's dominance frontier.
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DominanceFrontier::iterator NBBI = DF->find(NBB);
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if (NBBI != DF->end()) {
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DominanceFrontier::DomSetType NBSet = NBBI->second;
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for (DominanceFrontier::DomSetType::iterator NI = NBSet.begin(),
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NE = NBSet.end(); NI != NE; ++NI) {
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BasicBlock *B = *NI;
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if (OutSiders.count(B))
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DF->removeFromFrontier(NBBI, B);
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}
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}
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}
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// MiddleBlocks are dominated by original pre header. SplitEdge updated
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// MiddleBlocks' dominance frontier appropriately.
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for (unsigned i = 0, e = MiddleBlocks.size(); i != e; ++i) {
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BasicBlock *MBB = MiddleBlocks[i];
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DT->changeImmediateDominator(MBB, OrigPreheader);
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}
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// All Outsiders are now dominated by original pre header.
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for (SmallPtrSet<BasicBlock *, 8>::iterator OI = OutSiders.begin(),
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OE = OutSiders.end(); OI != OE; ++OI) {
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BasicBlock *OB = *OI;
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DT->changeImmediateDominator(OB, OrigPreheader);
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}
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// New loop headers are dominated by original preheader
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DT->changeImmediateDominator(NewBlocks[0], OrigPreheader);
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DT->changeImmediateDominator(LoopBlocks[0], OrigPreheader);
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}
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LoopProcessWorklist.push_back(NewLoop);
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redoLoop = true;
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@ -627,6 +627,15 @@ void DominanceFrontier::splitBlock(BasicBlock *NewBB) {
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if (!DT.dominates(NewBB, NewBBSucc))
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NewBBDominatesNewBBSucc = false;
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// NewBBSucc inherites original NewBB frontier.
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DominanceFrontier::iterator NewBBI = find(NewBB);
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if (NewBBI != end()) {
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DominanceFrontier::DomSetType NewBBSet = NewBBI->second;
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DominanceFrontier::DomSetType NewBBSuccSet;
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NewBBSuccSet.insert(NewBBSet.begin(), NewBBSet.end());
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addBasicBlock(NewBBSucc, NewBBSuccSet);
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}
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// If NewBB dominates NewBBSucc, then DF(NewBB) is now going to be the
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// DF(PredBlocks[0]) without the stuff that the new block does not dominate
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// a predecessor of.
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@ -648,7 +657,6 @@ void DominanceFrontier::splitBlock(BasicBlock *NewBB) {
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++SetI;
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}
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DominanceFrontier::iterator NewBBI = find(NewBB);
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if (NewBBI != end()) {
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DominanceFrontier::DomSetType NewBBSet = NewBBI->second;
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NewBBSet.insert(Set.begin(), Set.end());
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30
test/Transforms/LoopUnswitch/2007-08-01-Dom.ll
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30
test/Transforms/LoopUnswitch/2007-08-01-Dom.ll
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@ -0,0 +1,30 @@
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; RUN: llvm-as < %s | opt -licm -loop-unswitch -disable-output
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; PR 1589
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%struct.QBasicAtomic = type { i32 }
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define void @_ZNK5QDate9addMonthsEi(%struct.QBasicAtomic* sret %agg.result, %struct.QBasicAtomic* %this, i32 %nmonths) {
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entry:
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br label %cond_true90
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bb16: ; preds = %cond_true90
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br i1 false, label %bb93, label %cond_true90
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bb45: ; preds = %cond_true90
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br i1 false, label %bb53, label %bb58
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bb53: ; preds = %bb45
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br i1 false, label %bb93, label %cond_true90
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bb58: ; preds = %bb45
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store i32 0, i32* null, align 4
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br i1 false, label %cond_true90, label %bb93
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cond_true90: ; preds = %bb58, %bb53, %bb16, %entry
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%nmonths_addr.016.1 = phi i32 [ %nmonths, %entry ], [ 0, %bb16 ], [ 0, %bb53 ], [ %nmonths_addr.016.1, %bb58 ] ; <i32> [#uses=2]
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%tmp14 = icmp slt i32 %nmonths_addr.016.1, -11 ; <i1> [#uses=1]
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br i1 %tmp14, label %bb16, label %bb45
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bb93: ; preds = %bb58, %bb53, %bb16
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ret void
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}
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