Author: Roman Lebedev Date: 2020-12-30T23:58:40+03:00 New Revision: a17025aa61b16021ee85ff5deec47a9ed40ae1d4
URL: https://github.com/llvm/llvm-project/commit/a17025aa61b16021ee85ff5deec47a9ed40ae1d4 DIFF: https://github.com/llvm/llvm-project/commit/a17025aa61b16021ee85ff5deec47a9ed40ae1d4.diff LOG: [SimplifyCFG] Teach switchToSelect() to preserve DomTree Added: Modified: llvm/lib/Transforms/Utils/SimplifyCFG.cpp llvm/test/Transforms/SimplifyCFG/switch-to-select-two-case.ll Removed: ################################################################################ diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp index c730c1427ec8..2b631175f55e 100644 --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp @@ -5282,7 +5282,8 @@ static Value *ConvertTwoCaseSwitch(const SwitchCaseResultVectorTy &ResultVector, // a select, fixing up PHI nodes and basic blocks. static void RemoveSwitchAfterSelectConversion(SwitchInst *SI, PHINode *PHI, Value *SelectValue, - IRBuilder<> &Builder) { + IRBuilder<> &Builder, + DomTreeUpdater *DTU) { BasicBlock *SelectBB = SI->getParent(); while (PHI->getBasicBlockIndex(SelectBB) >= 0) PHI->removeIncomingValue(SelectBB); @@ -5290,6 +5291,8 @@ static void RemoveSwitchAfterSelectConversion(SwitchInst *SI, PHINode *PHI, Builder.CreateBr(PHI->getParent()); + std::vector<DominatorTree::UpdateType> Updates; + // Remove the switch. for (unsigned i = 0, e = SI->getNumSuccessors(); i < e; ++i) { BasicBlock *Succ = SI->getSuccessor(i); @@ -5297,15 +5300,18 @@ static void RemoveSwitchAfterSelectConversion(SwitchInst *SI, PHINode *PHI, if (Succ == PHI->getParent()) continue; Succ->removePredecessor(SelectBB); + Updates.push_back({DominatorTree::Delete, SelectBB, Succ}); } SI->eraseFromParent(); + if (DTU) + DTU->applyUpdatesPermissive(Updates); } /// If the switch is only used to initialize one or more /// phi nodes in a common successor block with only two diff erent /// constant values, replace the switch with select. static bool switchToSelect(SwitchInst *SI, IRBuilder<> &Builder, - const DataLayout &DL, + DomTreeUpdater *DTU, const DataLayout &DL, const TargetTransformInfo &TTI) { Value *const Cond = SI->getCondition(); PHINode *PHI = nullptr; @@ -5325,7 +5331,7 @@ static bool switchToSelect(SwitchInst *SI, IRBuilder<> &Builder, Value *SelectValue = ConvertTwoCaseSwitch(UniqueResults, DefaultResult, Cond, Builder); if (SelectValue) { - RemoveSwitchAfterSelectConversion(SI, PHI, SelectValue, Builder); + RemoveSwitchAfterSelectConversion(SI, PHI, SelectValue, Builder, DTU); return true; } // The switch couldn't be converted into a select. @@ -6081,7 +6087,7 @@ bool SimplifyCFGOpt::simplifySwitch(SwitchInst *SI, IRBuilder<> &Builder) { if (eliminateDeadSwitchCases(SI, Options.AC, DL)) return requestResimplify(); - if (switchToSelect(SI, Builder, DL, TTI)) + if (switchToSelect(SI, Builder, DTU, DL, TTI)) return requestResimplify(); if (Options.ForwardSwitchCondToPhi && ForwardSwitchConditionToPHI(SI)) diff --git a/llvm/test/Transforms/SimplifyCFG/switch-to-select-two-case.ll b/llvm/test/Transforms/SimplifyCFG/switch-to-select-two-case.ll index 31f5410bae40..bd3d5dff94d3 100644 --- a/llvm/test/Transforms/SimplifyCFG/switch-to-select-two-case.ll +++ b/llvm/test/Transforms/SimplifyCFG/switch-to-select-two-case.ll @@ -1,4 +1,4 @@ -; RUN: opt < %s -simplifycfg -S | FileCheck %s +; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s ; int foo1_with_default(int a) { ; switch(a) { _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
