From 27db7afd93a414c70ec7149ce107940800051c0a Mon Sep 17 00:00:00 2001 From: XChy Date: Fri, 10 Oct 2025 16:25:23 +0800 Subject: [PATCH 1/2] [DFAJumpThreading] Use a single lazy DTU --- .../Transforms/Scalar/DFAJumpThreading.cpp | 53 +++++++++---------- 1 file changed, 26 insertions(+), 27 deletions(-) diff --git a/llvm/lib/Transforms/Scalar/DFAJumpThreading.cpp b/llvm/lib/Transforms/Scalar/DFAJumpThreading.cpp index f4e05a204c9cf..65e6cc9aa1a7b 100644 --- a/llvm/lib/Transforms/Scalar/DFAJumpThreading.cpp +++ b/llvm/lib/Transforms/Scalar/DFAJumpThreading.cpp @@ -148,19 +148,17 @@ class SelectInstToUnfold { class DFAJumpThreading { public: - DFAJumpThreading(AssumptionCache *AC, DominatorTree *DT, LoopInfo *LI, + DFAJumpThreading(AssumptionCache *AC, DomTreeUpdater *DTU, LoopInfo *LI, TargetTransformInfo *TTI, OptimizationRemarkEmitter *ORE) - : AC(AC), DT(DT), LI(LI), TTI(TTI), ORE(ORE) {} + : AC(AC), DTU(DTU), LI(LI), TTI(TTI), ORE(ORE) {} bool run(Function &F); bool LoopInfoBroken; private: void - unfoldSelectInstrs(DominatorTree *DT, - const SmallVector &SelectInsts) { + unfoldSelectInstrs(const SmallVector &SelectInsts) { // TODO: Have everything use a single lazy DTU - DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Lazy); SmallVector Stack(SelectInsts); while (!Stack.empty()) { @@ -168,7 +166,7 @@ class DFAJumpThreading { std::vector NewSIsToUnfold; std::vector NewBBs; - unfold(&DTU, LI, SIToUnfold, &NewSIsToUnfold, &NewBBs); + unfold(DTU, LI, SIToUnfold, &NewSIsToUnfold, &NewBBs); // Put newly discovered select instructions into the work list. llvm::append_range(Stack, NewSIsToUnfold); @@ -181,7 +179,7 @@ class DFAJumpThreading { std::vector *NewBBs); AssumptionCache *AC; - DominatorTree *DT; + DomTreeUpdater *DTU; LoopInfo *LI; TargetTransformInfo *TTI; OptimizationRemarkEmitter *ORE; @@ -869,11 +867,11 @@ struct AllSwitchPaths { }; struct TransformDFA { - TransformDFA(AllSwitchPaths *SwitchPaths, DominatorTree *DT, + TransformDFA(AllSwitchPaths *SwitchPaths, DomTreeUpdater *DTU, AssumptionCache *AC, TargetTransformInfo *TTI, OptimizationRemarkEmitter *ORE, SmallPtrSet EphValues) - : SwitchPaths(SwitchPaths), DT(DT), AC(AC), TTI(TTI), ORE(ORE), + : SwitchPaths(SwitchPaths), DTU(DTU), AC(AC), TTI(TTI), ORE(ORE), EphValues(EphValues) {} bool run() { @@ -1049,19 +1047,16 @@ struct TransformDFA { SmallPtrSet BlocksToClean; BlocksToClean.insert_range(successors(SwitchBlock)); - { - DomTreeUpdater DTU(*DT, DomTreeUpdater::UpdateStrategy::Lazy); - for (const ThreadingPath &TPath : SwitchPaths->getThreadingPaths()) { - createExitPath(NewDefs, TPath, DuplicateMap, BlocksToClean, &DTU); - NumPaths++; - } - - // After all paths are cloned, now update the last successor of the cloned - // path so it skips over the switch statement - for (const ThreadingPath &TPath : SwitchPaths->getThreadingPaths()) - updateLastSuccessor(TPath, DuplicateMap, &DTU); + for (const ThreadingPath &TPath : SwitchPaths->getThreadingPaths()) { + createExitPath(NewDefs, TPath, DuplicateMap, BlocksToClean, DTU); + NumPaths++; } + // After all paths are cloned, now update the last successor of the cloned + // path so it skips over the switch statement + for (const ThreadingPath &TPath : SwitchPaths->getThreadingPaths()) + updateLastSuccessor(TPath, DuplicateMap, DTU); + // For each instruction that was cloned and used outside, update its uses updateSSA(NewDefs); @@ -1165,7 +1160,7 @@ struct TransformDFA { } // SSAUpdater handles phi placement and renaming uses with the appropriate // value. - SSAUpdate.RewriteAllUses(DT); + SSAUpdate.RewriteAllUses(&DTU->getDomTree()); } /// Clones a basic block, and adds it to the CFG. @@ -1388,7 +1383,7 @@ struct TransformDFA { } AllSwitchPaths *SwitchPaths; - DominatorTree *DT; + DomTreeUpdater *DTU; AssumptionCache *AC; TargetTransformInfo *TTI; OptimizationRemarkEmitter *ORE; @@ -1431,7 +1426,7 @@ bool DFAJumpThreading::run(Function &F) { << "candidate for jump threading\n"); LLVM_DEBUG(SI->dump()); - unfoldSelectInstrs(DT, Switch.getSelectInsts()); + unfoldSelectInstrs(Switch.getSelectInsts()); if (!Switch.getSelectInsts().empty()) MadeChanges = true; @@ -1453,7 +1448,7 @@ bool DFAJumpThreading::run(Function &F) { } #ifdef NDEBUG - LI->verify(*DT); + LI->verify(DTU->getDomTree()); #endif SmallPtrSet EphValues; @@ -1461,13 +1456,15 @@ bool DFAJumpThreading::run(Function &F) { CodeMetrics::collectEphemeralValues(&F, AC, EphValues); for (AllSwitchPaths SwitchPaths : ThreadableLoops) { - TransformDFA Transform(&SwitchPaths, DT, AC, TTI, ORE, EphValues); + TransformDFA Transform(&SwitchPaths, DTU, AC, TTI, ORE, EphValues); if (Transform.run()) MadeChanges = LoopInfoBroken = true; } + DTU->flush(); + #ifdef EXPENSIVE_CHECKS - assert(DT->verify(DominatorTree::VerificationLevel::Full)); + assert(DTU->getDomTree().verify(DominatorTree::VerificationLevel::Full)); verifyFunction(F, &dbgs()); #endif @@ -1482,7 +1479,9 @@ PreservedAnalyses DFAJumpThreadingPass::run(Function &F, LoopInfo &LI = AM.getResult(F); TargetTransformInfo &TTI = AM.getResult(F); OptimizationRemarkEmitter ORE(&F); - DFAJumpThreading ThreadImpl(&AC, &DT, &LI, &TTI, &ORE); + + DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Lazy); + DFAJumpThreading ThreadImpl(&AC, &DTU, &LI, &TTI, &ORE); if (!ThreadImpl.run(F)) return PreservedAnalyses::all(); From 3d709aba9ef05b26f0366bd2b3e58f7f6d9c497c Mon Sep 17 00:00:00 2001 From: XChy Date: Fri, 10 Oct 2025 16:38:41 +0800 Subject: [PATCH 2/2] remove comment --- llvm/lib/Transforms/Scalar/DFAJumpThreading.cpp | 1 - 1 file changed, 1 deletion(-) diff --git a/llvm/lib/Transforms/Scalar/DFAJumpThreading.cpp b/llvm/lib/Transforms/Scalar/DFAJumpThreading.cpp index 65e6cc9aa1a7b..e5935f4748c7f 100644 --- a/llvm/lib/Transforms/Scalar/DFAJumpThreading.cpp +++ b/llvm/lib/Transforms/Scalar/DFAJumpThreading.cpp @@ -158,7 +158,6 @@ class DFAJumpThreading { private: void unfoldSelectInstrs(const SmallVector &SelectInsts) { - // TODO: Have everything use a single lazy DTU SmallVector Stack(SelectInsts); while (!Stack.empty()) {