diff options
| -rw-r--r-- | lib/CodeGen/TailDuplication.cpp | 50 |
1 files changed, 37 insertions, 13 deletions
diff --git a/lib/CodeGen/TailDuplication.cpp b/lib/CodeGen/TailDuplication.cpp index b53ebec..bf58902 100644 --- a/lib/CodeGen/TailDuplication.cpp +++ b/lib/CodeGen/TailDuplication.cpp @@ -90,7 +90,8 @@ namespace { SmallSetVector<MachineBasicBlock*, 8> &Succs); bool TailDuplicateBlocks(MachineFunction &MF); bool TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF, - SmallVector<MachineBasicBlock*, 8> &TDBBs); + SmallVector<MachineBasicBlock*, 8> &TDBBs, + SmallVector<MachineInstr*, 16> &Copies); void RemoveDeadBlock(MachineBasicBlock *MBB); }; @@ -194,7 +195,8 @@ bool TailDuplicatePass::TailDuplicateBlocks(MachineFunction &MF) { MBB->succ_end()); SmallVector<MachineBasicBlock*, 8> TDBBs; - if (TailDuplicate(MBB, MF, TDBBs)) { + SmallVector<MachineInstr*, 16> Copies; + if (TailDuplicate(MBB, MF, TDBBs, Copies)) { ++NumTails; // TailBB's immediate successors are now successors of those predecessors @@ -251,6 +253,21 @@ bool TailDuplicatePass::TailDuplicateBlocks(MachineFunction &MF) { SSAUpdateVals.clear(); } + // Eliminate some of the copies inserted tail duplication to maintain + // SSA form. + for (unsigned i = 0, e = Copies.size(); i != e; ++i) { + MachineInstr *Copy = Copies[i]; + unsigned Src, Dst, SrcSR, DstSR; + if (TII->isMoveInstr(*Copy, Src, Dst, SrcSR, DstSR)) { + MachineRegisterInfo::use_iterator UI = MRI->use_begin(Src); + if (++UI == MRI->use_end()) { + // Copy is the only use. Do trivial copy propagation here. + MRI->replaceRegWith(Dst, Src); + Copy->eraseFromParent(); + } + } + } + if (PreRegAlloc && TailDupVerify) VerifyPHIs(MF, false); MadeChange = true; @@ -418,7 +435,8 @@ TailDuplicatePass::UpdateSuccessorsPHIs(MachineBasicBlock *FromBB, bool isDead, /// of its predecessors. bool TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF, - SmallVector<MachineBasicBlock*, 8> &TDBBs) { + SmallVector<MachineBasicBlock*, 8> &TDBBs, + SmallVector<MachineInstr*, 16> &Copies) { // Don't try to tail-duplicate single-block loops. if (TailBB->isSuccessor(TailBB)) return false; @@ -502,7 +520,7 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF, // Clone the contents of TailBB into PredBB. DenseMap<unsigned, unsigned> LocalVRMap; - SmallVector<std::pair<unsigned,unsigned>, 4> Copies; + SmallVector<std::pair<unsigned,unsigned>, 4> CopyInfos; MachineBasicBlock::iterator I = TailBB->begin(); while (I != TailBB->end()) { MachineInstr *MI = &*I; @@ -510,7 +528,7 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF, if (MI->getOpcode() == TargetInstrInfo::PHI) { // Replace the uses of the def of the PHI with the register coming // from PredBB. - ProcessPHI(MI, TailBB, PredBB, LocalVRMap, Copies); + ProcessPHI(MI, TailBB, PredBB, LocalVRMap, CopyInfos); } else { // Replace def of virtual registers with new registers, and update // uses with PHI source register or the new registers. @@ -518,9 +536,12 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF, } } MachineBasicBlock::iterator Loc = PredBB->getFirstTerminator(); - for (unsigned i = 0, e = Copies.size(); i != e; ++i) { - const TargetRegisterClass *RC = MRI->getRegClass(Copies[i].first); - TII->copyRegToReg(*PredBB, Loc, Copies[i].first, Copies[i].second, RC, RC); + for (unsigned i = 0, e = CopyInfos.size(); i != e; ++i) { + const TargetRegisterClass *RC = MRI->getRegClass(CopyInfos[i].first); + TII->copyRegToReg(*PredBB, Loc, CopyInfos[i].first, + CopyInfos[i].second, RC,RC); + MachineInstr *CopyMI = prior(Loc); + Copies.push_back(CopyMI); } NumInstrDups += TailBB->size() - 1; // subtract one for removed branch @@ -553,14 +574,14 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF, << "From MBB: " << *TailBB); if (PreRegAlloc) { DenseMap<unsigned, unsigned> LocalVRMap; - SmallVector<std::pair<unsigned,unsigned>, 4> Copies; + SmallVector<std::pair<unsigned,unsigned>, 4> CopyInfos; MachineBasicBlock::iterator I = TailBB->begin(); // Process PHI instructions first. while (I != TailBB->end() && I->getOpcode() == TargetInstrInfo::PHI) { // Replace the uses of the def of the PHI with the register coming // from PredBB. MachineInstr *MI = &*I++; - ProcessPHI(MI, TailBB, PrevBB, LocalVRMap, Copies); + ProcessPHI(MI, TailBB, PrevBB, LocalVRMap, CopyInfos); if (MI->getParent()) MI->eraseFromParent(); } @@ -574,9 +595,12 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF, MI->eraseFromParent(); } MachineBasicBlock::iterator Loc = PrevBB->getFirstTerminator(); - for (unsigned i = 0, e = Copies.size(); i != e; ++i) { - const TargetRegisterClass *RC = MRI->getRegClass(Copies[i].first); - TII->copyRegToReg(*PrevBB, Loc, Copies[i].first, Copies[i].second, RC, RC); + for (unsigned i = 0, e = CopyInfos.size(); i != e; ++i) { + const TargetRegisterClass *RC = MRI->getRegClass(CopyInfos[i].first); + TII->copyRegToReg(*PrevBB, Loc, CopyInfos[i].first, + CopyInfos[i].second, RC, RC); + MachineInstr *CopyMI = prior(Loc); + Copies.push_back(CopyMI); } } else { // No PHIs to worry about, just splice the instructions over. |