diff options
Diffstat (limited to 'llvm/lib/CodeGen/MachineBlockPlacement.cpp')
| -rw-r--r-- | llvm/lib/CodeGen/MachineBlockPlacement.cpp | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/llvm/lib/CodeGen/MachineBlockPlacement.cpp b/llvm/lib/CodeGen/MachineBlockPlacement.cpp index c562af9d964..2900fef7a55 100644 --- a/llvm/lib/CodeGen/MachineBlockPlacement.cpp +++ b/llvm/lib/CodeGen/MachineBlockPlacement.cpp @@ -496,8 +496,7 @@ MachineBlockPlacement::selectBestSuccessor(MachineBasicBlock *BB, // Make sure that a hot successor doesn't have a globally more // important predecessor. auto RealSuccProb = MBPI->getEdgeProbability(BB, Succ); - BlockFrequency CandidateEdgeFreq = - MBFI->getBlockFreq(BB) * RealSuccProb * HotProb.getCompl(); + BlockFrequency CandidateEdgeFreq = MBFI->getBlockFreq(BB) * RealSuccProb; bool BadCFGConflict = false; for (MachineBasicBlock *Pred : Succ->predecessors()) { if (Pred == Succ || BlockToChain[Pred] == &SuccChain || @@ -506,7 +505,15 @@ MachineBlockPlacement::selectBestSuccessor(MachineBasicBlock *BB, continue; BlockFrequency PredEdgeFreq = MBFI->getBlockFreq(Pred) * MBPI->getEdgeProbability(Pred, Succ); - if (PredEdgeFreq >= CandidateEdgeFreq) { + // A B + // \ / + // C + // We layout ACB iff A.freq > C.freq * HotProb + // i.e. A.freq > A.freq * HotProb + B.freq * HotProb + // i.e. A.freq * (1 - HotProb) > B.freq * HotProb + // A: CandidateEdge + // B: PredEdge + if (PredEdgeFreq * HotProb >= CandidateEdgeFreq * HotProb.getCompl()) { BadCFGConflict = true; break; } |
