Author: Roman Lebedev Date: 2021-01-04T01:02:02+03:00 New Revision: a7684940f0e4eafb1bafc75cfb0e620ee358abd4
URL: https://github.com/llvm/llvm-project/commit/a7684940f0e4eafb1bafc75cfb0e620ee358abd4 DIFF: https://github.com/llvm/llvm-project/commit/a7684940f0e4eafb1bafc75cfb0e620ee358abd4.diff LOG: [SimplifyCFG] SimplifyTerminatorOnSelect(): fix/tune DomTree updates We only need to remove non-TrueBB/non-FalseBB successors, and we only need to do that once. We don't need to insert any new edges, because no new successors will be added. Added: Modified: llvm/lib/Transforms/Utils/SimplifyCFG.cpp llvm/test/Transforms/SimplifyCFG/SimplifyTerminatorOnSelect-domtree-preservation-edgecase.ll Removed: ################################################################################ diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp index d4f77757a290..f02ff2252f7d 100644 --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp @@ -3849,7 +3849,6 @@ bool SimplifyCFGOpt::SimplifyTerminatorOnSelect(Instruction *OldTerm, uint32_t TrueWeight, uint32_t FalseWeight) { auto *BB = OldTerm->getParent(); - // Remove any superfluous successor edges from the CFG. // First, figure out which successors to preserve. // If TrueBB and FalseBB are equal, only try to preserve one copy of that @@ -3857,7 +3856,7 @@ bool SimplifyCFGOpt::SimplifyTerminatorOnSelect(Instruction *OldTerm, BasicBlock *KeepEdge1 = TrueBB; BasicBlock *KeepEdge2 = TrueBB != FalseBB ? FalseBB : nullptr; - SmallVector<DominatorTree::UpdateType, 4> Updates; + SmallSetVector<BasicBlock *, 2> RemovedSuccessors; // Then remove the rest. for (BasicBlock *Succ : successors(OldTerm)) { @@ -3869,7 +3868,9 @@ bool SimplifyCFGOpt::SimplifyTerminatorOnSelect(Instruction *OldTerm, else { Succ->removePredecessor(BB, /*KeepOneInputPHIs=*/true); - Updates.push_back({DominatorTree::Delete, BB, Succ}); + + if (Succ != TrueBB && Succ != FalseBB) + RemovedSuccessors.insert(Succ); } } @@ -3882,13 +3883,10 @@ bool SimplifyCFGOpt::SimplifyTerminatorOnSelect(Instruction *OldTerm, // We were only looking for one successor, and it was present. // Create an unconditional branch to it. Builder.CreateBr(TrueBB); - Updates.push_back({DominatorTree::Insert, BB, TrueBB}); } else { // We found both of the successors we were looking for. // Create a conditional branch sharing the condition of the select. BranchInst *NewBI = Builder.CreateCondBr(Cond, TrueBB, FalseBB); - Updates.push_back({DominatorTree::Insert, BB, TrueBB}); - Updates.push_back({DominatorTree::Insert, BB, FalseBB}); if (TrueWeight != FalseWeight) setBranchWeights(NewBI, TrueWeight, FalseWeight); } @@ -3903,17 +3901,22 @@ bool SimplifyCFGOpt::SimplifyTerminatorOnSelect(Instruction *OldTerm, if (!KeepEdge1) { // Only TrueBB was found. Builder.CreateBr(TrueBB); - Updates.push_back({DominatorTree::Insert, BB, TrueBB}); } else { // Only FalseBB was found. Builder.CreateBr(FalseBB); - Updates.push_back({DominatorTree::Insert, BB, FalseBB}); } } EraseTerminatorAndDCECond(OldTerm); - if (DTU) - DTU->applyUpdatesPermissive(Updates); + + if (DTU) { + SmallVector<DominatorTree::UpdateType, 2> Updates; + Updates.reserve(RemovedSuccessors.size()); + for (auto *RemovedSuccessor : RemovedSuccessors) + Updates.push_back({DominatorTree::Delete, BB, RemovedSuccessor}); + DTU->applyUpdates(Updates); + } + return true; } diff --git a/llvm/test/Transforms/SimplifyCFG/SimplifyTerminatorOnSelect-domtree-preservation-edgecase.ll b/llvm/test/Transforms/SimplifyCFG/SimplifyTerminatorOnSelect-domtree-preservation-edgecase.ll index 752de63c2933..792a1a534a93 100644 --- a/llvm/test/Transforms/SimplifyCFG/SimplifyTerminatorOnSelect-domtree-preservation-edgecase.ll +++ b/llvm/test/Transforms/SimplifyCFG/SimplifyTerminatorOnSelect-domtree-preservation-edgecase.ll @@ -1,5 +1,5 @@ ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py -; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=0 < %s | FileCheck %s +; RUN: opt -S -simplifycfg -simplifycfg-require-and-preserve-domtree=1 < %s | FileCheck %s declare void @widget() declare void @baz(i8) _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
