Author: Roman Lebedev Date: 2021-01-01T03:25:25+03:00 New Revision: 831636b0e6321500fd7bf3f32e8663369152a956
URL: https://github.com/llvm/llvm-project/commit/831636b0e6321500fd7bf3f32e8663369152a956 DIFF: https://github.com/llvm/llvm-project/commit/831636b0e6321500fd7bf3f32e8663369152a956.diff LOG: [SimplifyCFG] SUCCESS! Teach createUnreachableSwitchDefault() to preserve DomTree This pretty much concludes patch series for updating SimplifyCFG to preserve DomTree. All 318 dedicated `-simplifycfg` tests now pass with `-simplifycfg-require-and-preserve-domtree=1`. There are a few leftovers that apparently don't have good test coverage. I do not yet know what gaps in test coverage will the wider-scale testing reveal, but the default flip might be close. Added: Modified: llvm/lib/Transforms/Utils/SimplifyCFG.cpp llvm/test/Transforms/SimplifyCFG/switch-range-to-icmp.ll Removed: ################################################################################ diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp index f513db3783fb..53353cd5e923 100644 --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp @@ -4783,15 +4783,29 @@ static bool CasesAreContiguous(SmallVectorImpl<ConstantInt *> &Cases) { return true; } -static void createUnreachableSwitchDefault(SwitchInst *Switch) { +static void createUnreachableSwitchDefault(SwitchInst *Switch, + DomTreeUpdater *DTU) { LLVM_DEBUG(dbgs() << "SimplifyCFG: switch default is dead.\n"); + auto *BB = Switch->getParent(); BasicBlock *NewDefaultBlock = - SplitBlockPredecessors(Switch->getDefaultDest(), Switch->getParent(), ""); + SplitBlockPredecessors(Switch->getDefaultDest(), Switch->getParent(), "", + DTU ? &DTU->getDomTree() : nullptr); + auto *OrigDefaultBlock = Switch->getDefaultDest(); Switch->setDefaultDest(&*NewDefaultBlock); - SplitBlock(&*NewDefaultBlock, &NewDefaultBlock->front()); + if (DTU) + DTU->applyUpdatesPermissive( + {{DominatorTree::Delete, BB, OrigDefaultBlock}, + {DominatorTree::Insert, BB, &*NewDefaultBlock}}); + SplitBlock(&*NewDefaultBlock, &NewDefaultBlock->front(), + DTU ? &DTU->getDomTree() : nullptr); + SmallVector<DominatorTree::UpdateType, 2> Updates; + for (auto *Successor : successors(NewDefaultBlock)) + Updates.push_back({DominatorTree::Delete, NewDefaultBlock, Successor}); auto *NewTerminator = NewDefaultBlock->getTerminator(); new UnreachableInst(Switch->getContext(), NewTerminator); EraseTerminatorAndDCECond(NewTerminator); + if (DTU) + DTU->applyUpdatesPermissive(Updates); } /// Turn a switch with two reachable destinations into an integer range @@ -4803,6 +4817,8 @@ bool SimplifyCFGOpt::TurnSwitchRangeIntoICmp(SwitchInst *SI, bool HasDefault = !isa<UnreachableInst>(SI->getDefaultDest()->getFirstNonPHIOrDbg()); + auto *BB = SI->getParent(); + // Partition the cases into two sets with diff erent destinations. BasicBlock *DestA = HasDefault ? SI->getDefaultDest() : nullptr; BasicBlock *DestB = nullptr; @@ -4906,11 +4922,17 @@ bool SimplifyCFGOpt::TurnSwitchRangeIntoICmp(SwitchInst *SI, // Clean up the default block - it may have phis or other instructions before // the unreachable terminator. if (!HasDefault) - createUnreachableSwitchDefault(SI); + createUnreachableSwitchDefault(SI, DTU); + + auto *UnreachableDefault = SI->getDefaultDest(); // Drop the switch. SI->eraseFromParent(); + if (!HasDefault && DTU) + DTU->applyUpdatesPermissive( + {{DominatorTree::Delete, BB, UnreachableDefault}}); + return true; } @@ -4957,7 +4979,7 @@ static bool eliminateDeadSwitchCases(SwitchInst *SI, DomTreeUpdater *DTU, if (HasDefault && DeadCases.empty() && NumUnknownBits < 64 /* avoid overflow */ && SI->getNumCases() == (1ULL << NumUnknownBits)) { - createUnreachableSwitchDefault(SI); + createUnreachableSwitchDefault(SI, /*DTU=*/nullptr); return true; } diff --git a/llvm/test/Transforms/SimplifyCFG/switch-range-to-icmp.ll b/llvm/test/Transforms/SimplifyCFG/switch-range-to-icmp.ll index d99e84b6b940..7125575b2f33 100644 --- a/llvm/test/Transforms/SimplifyCFG/switch-range-to-icmp.ll +++ b/llvm/test/Transforms/SimplifyCFG/switch-range-to-icmp.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 declare i32 @f(i32) _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
