| commit 8e8d214c4a6c417e42996faeb9211a5c2e32111f |
| Author: Roman Lebedev <lebedev.ri@gmail.com> |
| Date: Sun Jan 10 16:25:15 2021 +0300 |
| |
| [NFCI][SimplifyCFG] Prefer to add Insert edges before Delete edges into DomTreeUpdater, if reasonable |
| |
| This has a measurable impact on the number of DomTree recalculations. |
| While this doesn't handle all the cases, |
| it deals with the most obvious ones. |
| |
| diff --git a/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp b/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp |
| index c0edde8648f5..44b9ddd3e1ee 100644 |
| --- a/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp |
| +++ b/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp |
| @@ -141,11 +141,11 @@ static bool mergeEmptyReturnBlocks(Function &F, DomTreeUpdater *DTU) { |
| // All predecessors of BB should now branch to RetBlock instead. |
| if (DTU) { |
| for (auto *Predecessor : predecessors(&BB)) { |
| - Updates.push_back({DominatorTree::Delete, Predecessor, &BB}); |
| // But, iff Predecessor already branches to RetBlock, |
| // don't (re-)add DomTree edge, because it already exists. |
| if (!is_contained(successors(Predecessor), RetBlock)) |
| Updates.push_back({DominatorTree::Insert, Predecessor, RetBlock}); |
| + Updates.push_back({DominatorTree::Delete, Predecessor, &BB}); |
| } |
| } |
| BB.replaceAllUsesWith(RetBlock); |
| diff --git a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp |
| index 0b3a25902c69..bfad88f64c7d 100644 |
| --- a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp |
| +++ b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp |
| @@ -1395,11 +1395,11 @@ BasicBlock *llvm::CreateControlFlowHub( |
| SmallVector<DominatorTree::UpdateType, 16> Updates; |
| if (DTU) { |
| for (auto In : Incoming) { |
| + Updates.push_back({DominatorTree::Insert, In, FirstGuardBlock}); |
| for (auto Succ : successors(In)) { |
| if (Outgoing.count(Succ)) |
| Updates.push_back({DominatorTree::Delete, In, Succ}); |
| } |
| - Updates.push_back({DominatorTree::Insert, In, FirstGuardBlock}); |
| } |
| } |
| |
| diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp |
| index 76bc8369fe5b..52e71ad164a5 100644 |
| --- a/llvm/lib/Transforms/Utils/Local.cpp |
| +++ b/llvm/lib/Transforms/Utils/Local.cpp |
| @@ -735,13 +735,13 @@ void llvm::MergeBasicBlockIntoOnlyPred(BasicBlock *DestBB, |
| SmallVector<DominatorTree::UpdateType, 32> Updates; |
| |
| if (DTU) { |
| - Updates.push_back({DominatorTree::Delete, PredBB, DestBB}); |
| for (auto I = pred_begin(PredBB), E = pred_end(PredBB); I != E; ++I) { |
| - Updates.push_back({DominatorTree::Delete, *I, PredBB}); |
| // This predecessor of PredBB may already have DestBB as a successor. |
| if (!llvm::is_contained(successors(*I), DestBB)) |
| Updates.push_back({DominatorTree::Insert, *I, DestBB}); |
| + Updates.push_back({DominatorTree::Delete, *I, PredBB}); |
| } |
| + Updates.push_back({DominatorTree::Delete, PredBB, DestBB}); |
| } |
| |
| // Zap anything that took the address of DestBB. Not doing this will give the |
| @@ -1046,16 +1046,16 @@ bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB, |
| |
| SmallVector<DominatorTree::UpdateType, 32> Updates; |
| if (DTU) { |
| - Updates.push_back({DominatorTree::Delete, BB, Succ}); |
| // All predecessors of BB will be moved to Succ. |
| SmallSetVector<BasicBlock *, 8> Predecessors(pred_begin(BB), pred_end(BB)); |
| Updates.reserve(Updates.size() + 2 * Predecessors.size()); |
| for (auto *Predecessor : Predecessors) { |
| - Updates.push_back({DominatorTree::Delete, Predecessor, BB}); |
| // This predecessor of BB may already have Succ as a successor. |
| if (!llvm::is_contained(successors(Predecessor), Succ)) |
| Updates.push_back({DominatorTree::Insert, Predecessor, Succ}); |
| + Updates.push_back({DominatorTree::Delete, Predecessor, BB}); |
| } |
| + Updates.push_back({DominatorTree::Delete, BB, Succ}); |
| } |
| |
| if (isa<PHINode>(Succ->begin())) { |
| diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp |
| index 4bcbffda6a61..62cab573a819 100644 |
| --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp |
| +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp |
| @@ -2495,8 +2495,8 @@ static bool FoldCondBranchOnPHI(BranchInst *BI, DomTreeUpdater *DTU, |
| PredBBTI->setSuccessor(i, EdgeBB); |
| } |
| |
| - Updates.push_back({DominatorTree::Delete, PredBB, BB}); |
| Updates.push_back({DominatorTree::Insert, PredBB, EdgeBB}); |
| + Updates.push_back({DominatorTree::Delete, PredBB, BB}); |
| |
| if (DTU) |
| DTU->applyUpdates(Updates); |
| @@ -2664,9 +2664,9 @@ static bool FoldTwoEntryPHINode(PHINode *PN, const TargetTransformInfo &TTI, |
| |
| SmallVector<DominatorTree::UpdateType, 3> Updates; |
| if (DTU) { |
| + Updates.push_back({DominatorTree::Insert, DomBlock, BB}); |
| for (auto *Successor : successors(DomBlock)) |
| Updates.push_back({DominatorTree::Delete, DomBlock, Successor}); |
| - Updates.push_back({DominatorTree::Insert, DomBlock, BB}); |
| } |
| |
| OldTI->eraseFromParent(); |
| @@ -3149,8 +3149,8 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI, DomTreeUpdater *DTU, |
| } else |
| PBI->setMetadata(LLVMContext::MD_prof, nullptr); |
| |
| - Updates.push_back({DominatorTree::Delete, PredBlock, BB}); |
| Updates.push_back({DominatorTree::Insert, PredBlock, UniqueSucc}); |
| + Updates.push_back({DominatorTree::Delete, PredBlock, BB}); |
| } else { |
| // Update PHI nodes in the common successors. |
| for (unsigned i = 0, e = PHIs.size(); i != e; ++i) { |
| @@ -3581,8 +3581,9 @@ static bool tryWidenCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI, |
| OldSuccessor->removePredecessor(BI->getParent()); |
| BI->setSuccessor(1, IfFalseBB); |
| if (DTU) |
| - DTU->applyUpdates({{DominatorTree::Delete, BI->getParent(), OldSuccessor}, |
| - {DominatorTree::Insert, BI->getParent(), IfFalseBB}}); |
| + DTU->applyUpdates( |
| + {{DominatorTree::Insert, BI->getParent(), IfFalseBB}, |
| + {DominatorTree::Delete, BI->getParent(), OldSuccessor}}); |
| return true; |
| } |
| if (BI->getSuccessor(0) != IfFalseBB && // no inf looping |
| @@ -3592,8 +3593,9 @@ static bool tryWidenCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI, |
| OldSuccessor->removePredecessor(BI->getParent()); |
| BI->setSuccessor(0, IfFalseBB); |
| if (DTU) |
| - DTU->applyUpdates({{DominatorTree::Delete, BI->getParent(), OldSuccessor}, |
| - {DominatorTree::Insert, BI->getParent(), IfFalseBB}}); |
| + DTU->applyUpdates( |
| + {{DominatorTree::Insert, BI->getParent(), IfFalseBB}, |
| + {DominatorTree::Delete, BI->getParent(), OldSuccessor}}); |
| return true; |
| } |
| return false; |
| @@ -3711,6 +3713,7 @@ static bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI, |
| // case, it would be unsafe to hoist the operation into a select instruction. |
| |
| BasicBlock *CommonDest = PBI->getSuccessor(PBIOp); |
| + BasicBlock *RemovedDest = PBI->getSuccessor(PBIOp ^ 1); |
| unsigned NumPhis = 0; |
| for (BasicBlock::iterator II = CommonDest->begin(); isa<PHINode>(II); |
| ++II, ++NumPhis) { |
| @@ -3773,16 +3776,13 @@ static bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI, |
| // Merge the conditions. |
| Value *Cond = Builder.CreateOr(PBICond, BICond, "brmerge"); |
| |
| - for (auto *Successor : successors(PBI->getParent())) |
| - Updates.push_back({DominatorTree::Delete, PBI->getParent(), Successor}); |
| - |
| // Modify PBI to branch on the new condition to the new dests. |
| PBI->setCondition(Cond); |
| PBI->setSuccessor(0, CommonDest); |
| PBI->setSuccessor(1, OtherDest); |
| |
| - for (auto *Successor : successors(PBI->getParent())) |
| - Updates.push_back({DominatorTree::Insert, PBI->getParent(), Successor}); |
| + Updates.push_back({DominatorTree::Insert, PBI->getParent(), OtherDest}); |
| + Updates.push_back({DominatorTree::Delete, PBI->getParent(), RemovedDest}); |
| |
| if (DTU) |
| DTU->applyUpdates(Updates); |
| @@ -4503,8 +4503,8 @@ static bool removeEmptyCleanup(CleanupReturnInst *RI, DomTreeUpdater *DTU) { |
| } else { |
| Instruction *TI = PredBB->getTerminator(); |
| TI->replaceUsesOfWith(BB, UnwindDest); |
| - Updates.push_back({DominatorTree::Delete, PredBB, BB}); |
| Updates.push_back({DominatorTree::Insert, PredBB, UnwindDest}); |
| + Updates.push_back({DominatorTree::Delete, PredBB, BB}); |
| } |
| } |
| |
| @@ -4764,10 +4764,10 @@ bool SimplifyCFGOpt::simplifyUnreachable(UnreachableInst *UI) { |
| // Redirect all predecessors of the block containing CatchSwitchInst |
| // to instead branch to the CatchSwitchInst's unwind destination. |
| for (auto *PredecessorOfPredecessor : predecessors(Predecessor)) { |
| - Updates.push_back( |
| - {DominatorTree::Delete, PredecessorOfPredecessor, Predecessor}); |
| Updates.push_back({DominatorTree::Insert, PredecessorOfPredecessor, |
| CSI->getUnwindDest()}); |
| + Updates.push_back( |
| + {DominatorTree::Delete, PredecessorOfPredecessor, Predecessor}); |
| } |
| Predecessor->replaceAllUsesWith(CSI->getUnwindDest()); |
| } else { |
| @@ -4834,8 +4834,8 @@ static void createUnreachableSwitchDefault(SwitchInst *Switch, |
| auto *OrigDefaultBlock = Switch->getDefaultDest(); |
| Switch->setDefaultDest(&*NewDefaultBlock); |
| if (DTU) |
| - DTU->applyUpdates({{DominatorTree::Delete, BB, OrigDefaultBlock}, |
| - {DominatorTree::Insert, BB, &*NewDefaultBlock}}); |
| + DTU->applyUpdates({{DominatorTree::Insert, BB, &*NewDefaultBlock}, |
| + {DominatorTree::Delete, BB, OrigDefaultBlock}}); |
| SplitBlock(&*NewDefaultBlock, &NewDefaultBlock->front(), |
| DTU ? &DTU->getDomTree() : nullptr); |
| SmallVector<DominatorTree::UpdateType, 2> Updates; |
| @@ -6344,8 +6344,8 @@ static bool TryToMergeLandingPad(LandingPadInst *LPad, BranchInst *BI, |
| assert(II->getNormalDest() != BB && II->getUnwindDest() == BB && |
| "unexpected successor"); |
| II->setUnwindDest(OtherPred); |
| - Updates.push_back({DominatorTree::Delete, Pred, BB}); |
| Updates.push_back({DominatorTree::Insert, Pred, OtherPred}); |
| + Updates.push_back({DominatorTree::Delete, Pred, BB}); |
| } |
| |
| // The debug info in OtherPred doesn't cover the merged control flow that |
