diff options
Diffstat (limited to 'llvm/lib/Transforms/Utils/SimplifyCFG.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Utils/SimplifyCFG.cpp | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp index 355410ad045..f0ed075cce6 100644 --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp @@ -2539,6 +2539,8 @@ static bool extractPredSuccWeights(BranchInst *PBI, BranchInst *BI, bool llvm::FoldBranchToCommonDest(BranchInst *BI, unsigned BonusInstThreshold) { BasicBlock *BB = BI->getParent(); + const unsigned PredCount = pred_size(BB); + Instruction *Cond = nullptr; if (BI->isConditional()) Cond = dyn_cast<Instruction>(BI->getCondition()); @@ -2588,7 +2590,8 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI, unsigned BonusInstThreshold) { // too many instructions and these involved instructions can be executed // unconditionally. We denote all involved instructions except the condition // as "bonus instructions", and only allow this transformation when the - // number of the bonus instructions does not exceed a certain threshold. + // number of the bonus instructions we'll need to create when cloning into + // each predecessor does not exceed a certain threshold. unsigned NumBonusInsts = 0; for (auto I = BB->begin(); Cond != &*I; ++I) { // Ignore dbg intrinsics. @@ -2603,7 +2606,10 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI, unsigned BonusInstThreshold) { // I is used in the same BB. Since BI uses Cond and doesn't have more slots // to use any other instruction, User must be an instruction between next(I) // and Cond. - ++NumBonusInsts; + + // Account for the cost of duplicating this instruction into each + // predecessor. + NumBonusInsts += PredCount; // Early exits once we reach the limit. if (NumBonusInsts > BonusInstThreshold) return false; |
