diff options
Diffstat (limited to 'lib/CodeGen/MachineBlockPlacement.cpp')
| -rw-r--r-- | lib/CodeGen/MachineBlockPlacement.cpp | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/lib/CodeGen/MachineBlockPlacement.cpp b/lib/CodeGen/MachineBlockPlacement.cpp index 5a15f92a18..93270772f0 100644 --- a/lib/CodeGen/MachineBlockPlacement.cpp +++ b/lib/CodeGen/MachineBlockPlacement.cpp @@ -985,8 +985,22 @@ void MachineBlockPlacement::buildCFGChains(MachineFunction &F) { // boiler plate. Cond.clear(); MachineBasicBlock *TBB = 0, *FBB = 0; // For AnalyzeBranch. - if (!TII->AnalyzeBranch(*PrevBB, TBB, FBB, Cond)) + if (!TII->AnalyzeBranch(*PrevBB, TBB, FBB, Cond)) { + // If PrevBB has a two-way branch, try to re-order the branches + // such that we branch to the successor with higher weight first. + if (TBB && !Cond.empty() && FBB && + MBPI->getEdgeWeight(PrevBB, FBB) > MBPI->getEdgeWeight(PrevBB, TBB) && + !TII->ReverseBranchCondition(Cond)) { + DEBUG(dbgs() << "Reverse order of the two branches: " + << getBlockName(PrevBB) << "\n"); + DEBUG(dbgs() << " Edge weight: " << MBPI->getEdgeWeight(PrevBB, FBB) + << " vs " << MBPI->getEdgeWeight(PrevBB, TBB) << "\n"); + DebugLoc dl; // FIXME: this is nowhere + TII->RemoveBranch(*PrevBB); + TII->InsertBranch(*PrevBB, FBB, TBB, Cond, dl); + } PrevBB->updateTerminator(); + } } // Fixup the last block. |