Author: Roman Lebedev Date: 2021-01-01T03:25:24+03:00 New Revision: a815b6b2b2cc483cfe9d2b520790322a39f8d37b
URL: https://github.com/llvm/llvm-project/commit/a815b6b2b2cc483cfe9d2b520790322a39f8d37b DIFF: https://github.com/llvm/llvm-project/commit/a815b6b2b2cc483cfe9d2b520790322a39f8d37b.diff LOG: [SimplifyCFG] Teach eliminateDeadSwitchCases() to preserve DomTree, part 1 Added: Modified: llvm/lib/Transforms/Utils/SimplifyCFG.cpp llvm/test/Transforms/SimplifyCFG/switch-masked-bits.ll llvm/test/Transforms/SimplifyCFG/switch-simplify-crash.ll Removed: ################################################################################ diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp index 402b98efadad..2ff576b17751 100644 --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp @@ -4908,7 +4908,8 @@ bool SimplifyCFGOpt::TurnSwitchRangeIntoICmp(SwitchInst *SI, /// Compute masked bits for the condition of a switch /// and use it to remove dead cases. -static bool eliminateDeadSwitchCases(SwitchInst *SI, AssumptionCache *AC, +static bool eliminateDeadSwitchCases(SwitchInst *SI, DomTreeUpdater *DTU, + AssumptionCache *AC, const DataLayout &DL) { Value *Cond = SI->getCondition(); unsigned Bits = Cond->getType()->getIntegerBitWidth(); @@ -4922,11 +4923,15 @@ static bool eliminateDeadSwitchCases(SwitchInst *SI, AssumptionCache *AC, // Gather dead cases. SmallVector<ConstantInt *, 8> DeadCases; + SmallMapVector<BasicBlock *, int, 8> NumPerSuccessorCases; for (auto &Case : SI->cases()) { + auto *Successor = Case.getCaseSuccessor(); + ++NumPerSuccessorCases[Successor]; const APInt &CaseVal = Case.getCaseValue()->getValue(); if (Known.Zero.intersects(CaseVal) || !Known.One.isSubsetOf(CaseVal) || (CaseVal.getMinSignedBits() > MaxSignificantBitsInCond)) { DeadCases.push_back(Case.getCaseValue()); + --NumPerSuccessorCases[Successor]; LLVM_DEBUG(dbgs() << "SimplifyCFG: switch case " << CaseVal << " is dead.\n"); } @@ -4961,6 +4966,13 @@ static bool eliminateDeadSwitchCases(SwitchInst *SI, AssumptionCache *AC, SIW.removeCase(CaseI); } + std::vector<DominatorTree::UpdateType> Updates; + for (const std::pair<BasicBlock *, int> &I : NumPerSuccessorCases) + if (I.second == 0) + Updates.push_back({DominatorTree::Delete, SI->getParent(), I.first}); + if (DTU) + DTU->applyUpdatesPermissive(Updates); + return true; } @@ -6132,7 +6144,7 @@ bool SimplifyCFGOpt::simplifySwitch(SwitchInst *SI, IRBuilder<> &Builder) { return requestResimplify(); // Remove unreachable cases. - if (eliminateDeadSwitchCases(SI, Options.AC, DL)) + if (eliminateDeadSwitchCases(SI, DTU, Options.AC, DL)) return requestResimplify(); if (switchToSelect(SI, Builder, DTU, DL, TTI)) diff --git a/llvm/test/Transforms/SimplifyCFG/switch-masked-bits.ll b/llvm/test/Transforms/SimplifyCFG/switch-masked-bits.ll index 21cecc5c942b..1b8d6e70b7dd 100644 --- a/llvm/test/Transforms/SimplifyCFG/switch-masked-bits.ll +++ b/llvm/test/Transforms/SimplifyCFG/switch-masked-bits.ll @@ -1,5 +1,5 @@ ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py -; RUN: opt -S -simplifycfg < %s | FileCheck %s +; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck %s define i32 @test1(i32 %x) nounwind { ; CHECK-LABEL: @test1( diff --git a/llvm/test/Transforms/SimplifyCFG/switch-simplify-crash.ll b/llvm/test/Transforms/SimplifyCFG/switch-simplify-crash.ll index bbc0bd78da7c..755ad0a16338 100644 --- a/llvm/test/Transforms/SimplifyCFG/switch-simplify-crash.ll +++ b/llvm/test/Transforms/SimplifyCFG/switch-simplify-crash.ll @@ -1,4 +1,4 @@ -; RUN: opt < %s -simplifycfg -disable-output +; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -disable-output define void @NewExtractNames() { entry: _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
