Author: Roman Lebedev Date: 2021-01-22T17:23:53+03:00 New Revision: b482560a597697789d81e4b9b22fb14e1f2f3c9a
URL: https://github.com/llvm/llvm-project/commit/b482560a597697789d81e4b9b22fb14e1f2f3c9a DIFF: https://github.com/llvm/llvm-project/commit/b482560a597697789d81e4b9b22fb14e1f2f3c9a.diff LOG: [NFC][SimplifyCFG] FoldBranchToCommonDest(): extract check for destination sharing into a helper function As a follow-up, i'll extract the actual transform into a function, and this helper will be called from both places, so this avoids code duplication. Added: Modified: llvm/lib/Transforms/Utils/SimplifyCFG.cpp Removed: ################################################################################ diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp index bdf4280609f1..4c830be4e6ab 100644 --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp @@ -2766,6 +2766,27 @@ static bool extractPredSuccWeights(BranchInst *PBI, BranchInst *BI, } } +// Determine if the two branches share a common destination, +// and deduce a glue that we need to use to join branch's conditions +// to arrive at the common destination. +static Optional<std::pair<Instruction::BinaryOps, bool>> +CheckIfCondBranchesShareCommonDestination(BranchInst *BI, BranchInst *PBI) { + assert(BI && PBI && BI->isConditional() && PBI->isConditional() && + "Both blocks must end with a conditional branches."); + assert(is_contained(predecessors(BI->getParent()), PBI->getParent()) && + "PredBB must be a predecessor of BB."); + + if (PBI->getSuccessor(0) == BI->getSuccessor(0)) + return {{Instruction::Or, false}}; + else if (PBI->getSuccessor(1) == BI->getSuccessor(1)) + return {{Instruction::And, false}}; + else if (PBI->getSuccessor(0) == BI->getSuccessor(1)) + return {{Instruction::And, true}}; + else if (PBI->getSuccessor(1) == BI->getSuccessor(0)) + return {{Instruction::Or, true}}; + return None; +} + /// If this basic block is simple enough, and if a predecessor branches to us /// and one of our successors, fold the block into the predecessor and use /// logical operations to pick the right destination. @@ -2868,22 +2889,12 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI, DomTreeUpdater *DTU, continue; // Determine if the two branches share a common destination. - Instruction::BinaryOps Opc = Instruction::BinaryOpsEnd; - bool InvertPredCond = false; - - if (PBI->getSuccessor(0) == TrueDest) { - Opc = Instruction::Or; - } else if (PBI->getSuccessor(1) == FalseDest) { - Opc = Instruction::And; - } else if (PBI->getSuccessor(0) == FalseDest) { - Opc = Instruction::And; - InvertPredCond = true; - } else if (PBI->getSuccessor(1) == TrueDest) { - Opc = Instruction::Or; - InvertPredCond = true; - } else { + Instruction::BinaryOps Opc; + bool InvertPredCond; + if (auto Recepie = CheckIfCondBranchesShareCommonDestination(BI, PBI)) + std::tie(Opc, InvertPredCond) = *Recepie; + else continue; - } // Check the cost of inserting the necessary logic before performing the // transformation. _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
