Author: Roman Lebedev Date: 2021-01-08T02:15:26+03:00 New Revision: 66189212bbb0351ae98bbda70bd2cd819e86fd17
URL: https://github.com/llvm/llvm-project/commit/66189212bbb0351ae98bbda70bd2cd819e86fd17 DIFF: https://github.com/llvm/llvm-project/commit/66189212bbb0351ae98bbda70bd2cd819e86fd17.diff LOG: [SimplifyCFG] MergeBlockIntoPredecessor(): switch to non-permissive DomTree updates ... which requires not deleting edges that were just deleted already, by not processing the same successor more than once. Added: Modified: llvm/lib/Transforms/Utils/BasicBlockUtils.cpp Removed: ################################################################################ diff --git a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp index 09888db063e2..4d99067438ad 100644 --- a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp +++ b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp @@ -230,19 +230,21 @@ bool llvm::MergeBlockIntoPredecessor(BasicBlock *BB, DomTreeUpdater *DTU, // These dominator edges will be redirected from Pred. std::vector<DominatorTree::UpdateType> Updates; if (DTU) { - Updates.reserve(1 + (2 * succ_size(BB))); + SmallSetVector<BasicBlock *, 2> UniqueSuccessors(succ_begin(BB), + succ_end(BB)); + Updates.reserve(1 + (2 * UniqueSuccessors.size())); // Add insert edges first. Experimentally, for the particular case of two // blocks that can be merged, with a single successor and single predecessor // respectively, it is beneficial to have all insert updates first. Deleting // edges first may lead to unreachable blocks, followed by inserting edges // making the blocks reachable again. Such DT updates lead to high compile // times. We add inserts before deletes here to reduce compile time. - for (auto I = succ_begin(BB), E = succ_end(BB); I != E; ++I) + for (BasicBlock *UniqueSuccessor : UniqueSuccessors) // This successor of BB may already have PredBB as a predecessor. - if (!llvm::is_contained(successors(PredBB), *I)) - Updates.push_back({DominatorTree::Insert, PredBB, *I}); - for (auto I = succ_begin(BB), E = succ_end(BB); I != E; ++I) - Updates.push_back({DominatorTree::Delete, BB, *I}); + if (!llvm::is_contained(successors(PredBB), UniqueSuccessor)) + Updates.push_back({DominatorTree::Insert, PredBB, UniqueSuccessor}); + for (BasicBlock *UniqueSuccessor : UniqueSuccessors) + Updates.push_back({DominatorTree::Delete, BB, UniqueSuccessor}); Updates.push_back({DominatorTree::Delete, PredBB, BB}); } @@ -303,7 +305,7 @@ bool llvm::MergeBlockIntoPredecessor(BasicBlock *BB, DomTreeUpdater *DTU, isa<UnreachableInst>(BB->getTerminator()) && "The successor list of BB isn't empty before " "applying corresponding DTU updates."); - DTU->applyUpdatesPermissive(Updates); + DTU->applyUpdates(Updates); DTU->deleteBB(BB); } else { BB->eraseFromParent(); // Nuke BB if DTU is nullptr. _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits