diff options
Diffstat (limited to 'lib/CodeGen/TailDuplication.cpp')
| -rw-r--r-- | lib/CodeGen/TailDuplication.cpp | 39 |
1 files changed, 23 insertions, 16 deletions
diff --git a/lib/CodeGen/TailDuplication.cpp b/lib/CodeGen/TailDuplication.cpp index bf58902..f51f74d 100644 --- a/lib/CodeGen/TailDuplication.cpp +++ b/lib/CodeGen/TailDuplication.cpp @@ -139,8 +139,8 @@ static void VerifyPHIs(MachineFunction &MF, bool CheckExtra) { } } if (!Found) { - errs() << "Malformed PHI in BB#" << MBB->getNumber() << ": " << *MI; - errs() << " missing input from predecessor BB#" + dbgs() << "Malformed PHI in BB#" << MBB->getNumber() << ": " << *MI; + dbgs() << " missing input from predecessor BB#" << PredBB->getNumber() << '\n'; llvm_unreachable(0); } @@ -150,14 +150,14 @@ static void VerifyPHIs(MachineFunction &MF, bool CheckExtra) { MachineBasicBlock *PHIBB = MI->getOperand(i+1).getMBB(); if (CheckExtra && !Preds.count(PHIBB)) { // This is not a hard error. - errs() << "Warning: malformed PHI in BB#" << MBB->getNumber() + dbgs() << "Warning: malformed PHI in BB#" << MBB->getNumber() << ": " << *MI; - errs() << " extra input from predecessor BB#" + dbgs() << " extra input from predecessor BB#" << PHIBB->getNumber() << '\n'; } if (PHIBB->getNumber() < 0) { - errs() << "Malformed PHI in BB#" << MBB->getNumber() << ": " << *MI; - errs() << " non-existing BB#" << PHIBB->getNumber() << '\n'; + dbgs() << "Malformed PHI in BB#" << MBB->getNumber() << ": " << *MI; + dbgs() << " non-existing BB#" << PHIBB->getNumber() << '\n'; llvm_unreachable(0); } } @@ -173,7 +173,7 @@ bool TailDuplicatePass::TailDuplicateBlocks(MachineFunction &MF) { bool MadeChange = false; if (PreRegAlloc && TailDupVerify) { - DEBUG(errs() << "\n*** Before tail-duplicating\n"); + DEBUG(dbgs() << "\n*** Before tail-duplicating\n"); VerifyPHIs(MF, true); } @@ -253,7 +253,7 @@ bool TailDuplicatePass::TailDuplicateBlocks(MachineFunction &MF) { SSAUpdateVals.clear(); } - // Eliminate some of the copies inserted tail duplication to maintain + // Eliminate some of the copies inserted by tail duplication to maintain // SSA form. for (unsigned i = 0, e = Copies.size(); i != e; ++i) { MachineInstr *Copy = Copies[i]; @@ -346,7 +346,7 @@ void TailDuplicatePass::DuplicateInstruction(MachineInstr *MI, MachineBasicBlock *PredBB, MachineFunction &MF, DenseMap<unsigned, unsigned> &LocalVRMap) { - MachineInstr *NewMI = MF.CloneMachineInstr(MI); + MachineInstr *NewMI = TII->duplicate(MI, MF); for (unsigned i = 0, e = NewMI->getNumOperands(); i != e; ++i) { MachineOperand &MO = NewMI->getOperand(i); if (!MO.isReg()) @@ -437,8 +437,11 @@ bool TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF, SmallVector<MachineBasicBlock*, 8> &TDBBs, SmallVector<MachineInstr*, 16> &Copies) { - // Don't try to tail-duplicate single-block loops. - if (TailBB->isSuccessor(TailBB)) + // Pre-regalloc tail duplication hurts compile time and doesn't help + // much except for indirect branches. + bool hasIndirectBranch = (!TailBB->empty() && + TailBB->back().getDesc().isIndirectBranch()); + if (PreRegAlloc && !hasIndirectBranch) return false; // Set the limit on the number of instructions to duplicate, with a default @@ -446,7 +449,7 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF, // duplicate only one, because one branch instruction can be eliminated to // compensate for the duplication. unsigned MaxDuplicateCount; - if (!TailBB->empty() && TailBB->back().getDesc().isIndirectBranch()) + if (hasIndirectBranch) // If the target has hardware branch prediction that can handle indirect // branches, duplicating them can often make them predictable when there // are common paths through the code. The limit needs to be high enough @@ -457,6 +460,10 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF, else MaxDuplicateCount = TailDuplicateSize; + // Don't try to tail-duplicate single-block loops. + if (TailBB->isSuccessor(TailBB)) + return false; + // Check the instructions in the block to determine whether tail-duplication // is invalid or unlikely to be profitable. unsigned InstrCount = 0; @@ -481,7 +488,7 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF, if (InstrCount > 1 && HasCall) return false; - DEBUG(errs() << "\n*** Tail-duplicating BB#" << TailBB->getNumber() << '\n'); + DEBUG(dbgs() << "\n*** Tail-duplicating BB#" << TailBB->getNumber() << '\n'); // Iterate through all the unique predecessors and tail-duplicate this // block into them, if possible. Copying the list ahead of time also @@ -510,7 +517,7 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF, if (PredBB->isLayoutSuccessor(TailBB) && PredBB->canFallThrough()) continue; - DEBUG(errs() << "\nTail-duplicating into PredBB: " << *PredBB + DEBUG(dbgs() << "\nTail-duplicating into PredBB: " << *PredBB << "From Succ: " << *TailBB); TDBBs.push_back(PredBB); @@ -570,7 +577,7 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF, if (!PriorUnAnalyzable && PriorCond.empty() && !PriorTBB && TailBB->pred_size() == 1 && PrevBB->succ_size() == 1 && !TailBB->hasAddressTaken()) { - DEBUG(errs() << "\nMerging into block: " << *PrevBB + DEBUG(dbgs() << "\nMerging into block: " << *PrevBB << "From MBB: " << *TailBB); if (PreRegAlloc) { DenseMap<unsigned, unsigned> LocalVRMap; @@ -620,7 +627,7 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF, /// function, updating the CFG. void TailDuplicatePass::RemoveDeadBlock(MachineBasicBlock *MBB) { assert(MBB->pred_empty() && "MBB must be dead!"); - DEBUG(errs() << "\nRemoving MBB: " << *MBB); + DEBUG(dbgs() << "\nRemoving MBB: " << *MBB); // Remove all successors. while (!MBB->succ_empty()) |
