diff options
Diffstat (limited to 'lib/CodeGen/MachineBasicBlock.cpp')
| -rw-r--r-- | lib/CodeGen/MachineBasicBlock.cpp | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/lib/CodeGen/MachineBasicBlock.cpp b/lib/CodeGen/MachineBasicBlock.cpp index a27ee47943..895653d18d 100644 --- a/lib/CodeGen/MachineBasicBlock.cpp +++ b/lib/CodeGen/MachineBasicBlock.cpp @@ -439,6 +439,14 @@ MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) { if (TII->AnalyzeBranch(*this, TBB, FBB, Cond)) return NULL; + // Avoid splitting backedges of loops. It would introduce small out-of-line + // blocks into the loop which is very bad for code placement. + if (this == Succ) + return NULL; + MachineLoopInfo *MLI = P->getAnalysisIfAvailable<MachineLoopInfo>(); + if (MLI->isLoopHeader(Succ)) + return NULL; + MachineBasicBlock *NMBB = MF->CreateMachineBasicBlock(); MF->insert(llvm::next(MachineFunction::iterator(this)), NMBB); DEBUG(dbgs() << "PHIElimination splitting critical edge:" @@ -471,8 +479,7 @@ MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) { P->getAnalysisIfAvailable<MachineDominatorTree>()) MDT->addNewBlock(NMBB, this); - if (MachineLoopInfo *MLI = - P->getAnalysisIfAvailable<MachineLoopInfo>()) + if (MLI) if (MachineLoop *TIL = MLI->getLoopFor(this)) { // If one or the other blocks were not in a loop, the new block is not // either, and thus LI doesn't need to be updated. |