diff options
Diffstat (limited to 'lib/CodeGen/MachineBlockPlacement.cpp')
| -rw-r--r-- | lib/CodeGen/MachineBlockPlacement.cpp | 32 |
1 files changed, 29 insertions, 3 deletions
diff --git a/lib/CodeGen/MachineBlockPlacement.cpp b/lib/CodeGen/MachineBlockPlacement.cpp index e83ae93528..4cbc94e0b7 100644 --- a/lib/CodeGen/MachineBlockPlacement.cpp +++ b/lib/CodeGen/MachineBlockPlacement.cpp @@ -365,9 +365,35 @@ MachineBasicBlock *MachineBlockPlacement::selectBestSuccessor( // Only consider successors which are either "hot", or wouldn't violate // any CFG constraints. - if (SuccChain.LoopPredecessors != 0 && SuccProb < HotProb) { - DEBUG(dbgs() << " " << getBlockName(*SI) << " -> CFG conflict\n"); - continue; + if (SuccChain.LoopPredecessors != 0) { + if (SuccProb < HotProb) { + DEBUG(dbgs() << " " << getBlockName(*SI) << " -> CFG conflict\n"); + continue; + } + + // Make sure that a hot successor doesn't have a globally more important + // predecessor. + BlockFrequency CandidateEdgeFreq + = MBFI->getBlockFreq(BB) * SuccProb * HotProb.getCompl(); + bool BadCFGConflict = false; + for (MachineBasicBlock::pred_iterator PI = (*SI)->pred_begin(), + PE = (*SI)->pred_end(); + PI != PE; ++PI) { + if (*PI == *SI || (BlockFilter && !BlockFilter->count(*PI)) || + BlockToChain[*PI] == &Chain) + continue; + BlockFrequency PredEdgeFreq + = MBFI->getBlockFreq(*PI) * MBPI->getEdgeProbability(*PI, *SI); + if (PredEdgeFreq >= CandidateEdgeFreq) { + BadCFGConflict = true; + break; + } + } + if (BadCFGConflict) { + DEBUG(dbgs() << " " << getBlockName(*SI) + << " -> non-cold CFG conflict\n"); + continue; + } } DEBUG(dbgs() << " " << getBlockName(*SI) << " -> " << SuccProb |