C++ instr_iterator::getNumOperands方法代码示例

void
MachineBasicBlock::transferSuccessorsAndUpdatePHIs(MachineBasicBlock *fromMBB) {
  if (this == fromMBB)
    return;

  while (!fromMBB->succ_empty()) {
    MachineBasicBlock *Succ = *fromMBB->succ_begin();
    uint32_t Weight = 0;
    if (!fromMBB->Weights.empty())
      Weight = *fromMBB->Weights.begin();
    addSuccessor(Succ, Weight);
    fromMBB->removeSuccessor(Succ);

    // Fix up any PHI nodes in the successor.
    for (MachineBasicBlock::instr_iterator MI = Succ->instr_begin(),
           ME = Succ->instr_end(); MI != ME && MI->isPHI(); ++MI)
      for (unsigned i = 2, e = MI->getNumOperands()+1; i != e; i += 2) {
        MachineOperand &MO = MI->getOperand(i);
        if (MO.getMBB() == fromMBB)
          MO.setMBB(this);
      }
  }
}

//.........这里部分代码省略.........
      NewTerminators.push_back(I);

    for (SmallVectorImpl<MachineInstr*>::iterator I = Terminators.begin(),
        E = Terminators.end(); I != E; ++I) {
      if (std::find(NewTerminators.begin(), NewTerminators.end(), *I) ==
          NewTerminators.end())
       Indexes->removeMachineInstrFromMaps(*I);
    }
  }

  // Insert unconditional "jump Succ" instruction in NMBB if necessary.
  NMBB->addSuccessor(Succ);
  if (!NMBB->isLayoutSuccessor(Succ)) {
    Cond.clear();
    MF->getSubtarget().getInstrInfo()->InsertBranch(*NMBB, Succ, nullptr, Cond,
                                                    dl);

    if (Indexes) {
      for (instr_iterator I = NMBB->instr_begin(), E = NMBB->instr_end();
           I != E; ++I) {
        // Some instructions may have been moved to NMBB by updateTerminator(),
        // so we first remove any instruction that already has an index.
        if (Indexes->hasIndex(I))
          Indexes->removeMachineInstrFromMaps(I);
        Indexes->insertMachineInstrInMaps(I);
      }
    }
  }

  // Fix PHI nodes in Succ so they refer to NMBB instead of this
  for (MachineBasicBlock::instr_iterator
         i = Succ->instr_begin(),e = Succ->instr_end();
       i != e && i->isPHI(); ++i)
    for (unsigned ni = 1, ne = i->getNumOperands(); ni != ne; ni += 2)
      if (i->getOperand(ni+1).getMBB() == this)
        i->getOperand(ni+1).setMBB(NMBB);

  // Inherit live-ins from the successor
  for (MachineBasicBlock::livein_iterator I = Succ->livein_begin(),
         E = Succ->livein_end(); I != E; ++I)
    NMBB->addLiveIn(*I);

  // Update LiveVariables.
  const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
  if (LV) {
    // Restore kills of virtual registers that were killed by the terminators.
    while (!KilledRegs.empty()) {
      unsigned Reg = KilledRegs.pop_back_val();
      for (instr_iterator I = instr_end(), E = instr_begin(); I != E;) {
        if (!(--I)->addRegisterKilled(Reg, TRI, /* addIfNotFound= */ false))
          continue;
        if (TargetRegisterInfo::isVirtualRegister(Reg))
          LV->getVarInfo(Reg).Kills.push_back(I);
        DEBUG(dbgs() << "Restored terminator kill: " << *I);
        break;
      }
    }
    // Update relevant live-through information.
    LV->addNewBlock(NMBB, this, Succ);
  }

  if (LIS) {
    // After splitting the edge and updating SlotIndexes, live intervals may be
    // in one of two situations, depending on whether this block was the last in
    // the function. If the original block was the last in the function, all live
    // intervals will end prior to the beginning of the new split block. If the

/// finalizeBundle - Finalize a machine instruction bundle which includes
/// a sequence of instructions starting from FirstMI to LastMI (exclusive).
/// This routine adds a BUNDLE instruction to represent the bundle, it adds
/// IsInternalRead markers to MachineOperands which are defined inside the
/// bundle, and it copies externally visible defs and uses to the BUNDLE
/// instruction.
void llvm::finalizeBundle(MachineBasicBlock &MBB,
                          MachineBasicBlock::instr_iterator FirstMI,
                          MachineBasicBlock::instr_iterator LastMI) {
  assert(FirstMI != LastMI && "Empty bundle?");
  MIBundleBuilder Bundle(MBB, FirstMI, LastMI);

  const TargetMachine &TM = MBB.getParent()->getTarget();
  const TargetInstrInfo *TII = TM.getSubtargetImpl()->getInstrInfo();
  const TargetRegisterInfo *TRI = TM.getSubtargetImpl()->getRegisterInfo();

  MachineInstrBuilder MIB = BuildMI(*MBB.getParent(), FirstMI->getDebugLoc(),
                                    TII->get(TargetOpcode::BUNDLE));
  Bundle.prepend(MIB);

  SmallVector<unsigned, 32> LocalDefs;
  SmallSet<unsigned, 32> LocalDefSet;
  SmallSet<unsigned, 8> DeadDefSet;
  SmallSet<unsigned, 16> KilledDefSet;
  SmallVector<unsigned, 8> ExternUses;
  SmallSet<unsigned, 8> ExternUseSet;
  SmallSet<unsigned, 8> KilledUseSet;
  SmallSet<unsigned, 8> UndefUseSet;
  SmallVector<MachineOperand*, 4> Defs;
  for (; FirstMI != LastMI; ++FirstMI) {
    for (unsigned i = 0, e = FirstMI->getNumOperands(); i != e; ++i) {
      MachineOperand &MO = FirstMI->getOperand(i);
      if (!MO.isReg())
        continue;
      if (MO.isDef()) {
        Defs.push_back(&MO);
        continue;
      }

      unsigned Reg = MO.getReg();
      if (!Reg)
        continue;
      assert(TargetRegisterInfo::isPhysicalRegister(Reg));
      if (LocalDefSet.count(Reg)) {
        MO.setIsInternalRead();
        if (MO.isKill())
          // Internal def is now killed.
          KilledDefSet.insert(Reg);
      } else {
        if (ExternUseSet.insert(Reg)) {
          ExternUses.push_back(Reg);
          if (MO.isUndef())
            UndefUseSet.insert(Reg);
        }
        if (MO.isKill())
          // External def is now killed.
          KilledUseSet.insert(Reg);
      }
    }

    for (unsigned i = 0, e = Defs.size(); i != e; ++i) {
      MachineOperand &MO = *Defs[i];
      unsigned Reg = MO.getReg();
      if (!Reg)
        continue;

      if (LocalDefSet.insert(Reg)) {
        LocalDefs.push_back(Reg);
        if (MO.isDead()) {
          DeadDefSet.insert(Reg);
        }
      } else {
        // Re-defined inside the bundle, it's no longer killed.
        KilledDefSet.erase(Reg);
        if (!MO.isDead())
          // Previously defined but dead.
          DeadDefSet.erase(Reg);
      }

      if (!MO.isDead()) {
        for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) {
          unsigned SubReg = *SubRegs;
          if (LocalDefSet.insert(SubReg))
            LocalDefs.push_back(SubReg);
        }
      }
    }

    Defs.clear();
  }

  SmallSet<unsigned, 32> Added;
  for (unsigned i = 0, e = LocalDefs.size(); i != e; ++i) {
    unsigned Reg = LocalDefs[i];
    if (Added.insert(Reg)) {
      // If it's not live beyond end of the bundle, mark it dead.
      bool isDead = DeadDefSet.count(Reg) || KilledDefSet.count(Reg);
      MIB.addReg(Reg, getDefRegState(true) | getDeadRegState(isDead) |
                 getImplRegState(true));
    }
//.........这里部分代码省略.........

MachineBasicBlock *
MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) {
  // Splitting the critical edge to a landing pad block is non-trivial. Don't do
  // it in this generic function.
  if (Succ->isLandingPad())
    return NULL;

  MachineFunction *MF = getParent();
  DebugLoc dl;  // FIXME: this is nowhere

  // We may need to update this's terminator, but we can't do that if
  // AnalyzeBranch fails. If this uses a jump table, we won't touch it.
  const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
  MachineBasicBlock *TBB = 0, *FBB = 0;
  SmallVector<MachineOperand, 4> Cond;
  if (TII->AnalyzeBranch(*this, TBB, FBB, Cond))
    return NULL;

  // Avoid bugpoint weirdness: A block may end with a conditional branch but
  // jumps to the same MBB is either case. We have duplicate CFG edges in that
  // case that we can't handle. Since this never happens in properly optimized
  // code, just skip those edges.
  if (TBB && TBB == FBB) {
    DEBUG(dbgs() << "Won't split critical edge after degenerate BB#"
                 << getNumber() << '\n');
    return NULL;
  }

  MachineBasicBlock *NMBB = MF->CreateMachineBasicBlock();
  MF->insert(llvm::next(MachineFunction::iterator(this)), NMBB);
  DEBUG(dbgs() << "Splitting critical edge:"
        " BB#" << getNumber()
        << " -- BB#" << NMBB->getNumber()
        << " -- BB#" << Succ->getNumber() << '\n');

  // On some targets like Mips, branches may kill virtual registers. Make sure
  // that LiveVariables is properly updated after updateTerminator replaces the
  // terminators.
  LiveVariables *LV = P->getAnalysisIfAvailable<LiveVariables>();

  // Collect a list of virtual registers killed by the terminators.
  SmallVector<unsigned, 4> KilledRegs;
  if (LV)
    for (instr_iterator I = getFirstInstrTerminator(), E = instr_end();
         I != E; ++I) {
      MachineInstr *MI = I;
      for (MachineInstr::mop_iterator OI = MI->operands_begin(),
           OE = MI->operands_end(); OI != OE; ++OI) {
        if (!OI->isReg() || OI->getReg() == 0 ||
            !OI->isUse() || !OI->isKill() || OI->isUndef())
          continue;
        unsigned Reg = OI->getReg();
        if (TargetRegisterInfo::isPhysicalRegister(Reg) ||
            LV->getVarInfo(Reg).removeKill(MI)) {
          KilledRegs.push_back(Reg);
          DEBUG(dbgs() << "Removing terminator kill: " << *MI);
          OI->setIsKill(false);
        }
      }
    }

  ReplaceUsesOfBlockWith(Succ, NMBB);
  updateTerminator();

  // Insert unconditional "jump Succ" instruction in NMBB if necessary.
  NMBB->addSuccessor(Succ);
  if (!NMBB->isLayoutSuccessor(Succ)) {
    Cond.clear();
    MF->getTarget().getInstrInfo()->InsertBranch(*NMBB, Succ, NULL, Cond, dl);
  }

  // Fix PHI nodes in Succ so they refer to NMBB instead of this
  for (MachineBasicBlock::instr_iterator
         i = Succ->instr_begin(),e = Succ->instr_end();
       i != e && i->isPHI(); ++i)
    for (unsigned ni = 1, ne = i->getNumOperands(); ni != ne; ni += 2)
      if (i->getOperand(ni+1).getMBB() == this)
        i->getOperand(ni+1).setMBB(NMBB);

  // Inherit live-ins from the successor
  for (MachineBasicBlock::livein_iterator I = Succ->livein_begin(),
         E = Succ->livein_end(); I != E; ++I)
    NMBB->addLiveIn(*I);

  // Update LiveVariables.
  const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo();
  if (LV) {
    // Restore kills of virtual registers that were killed by the terminators.
    while (!KilledRegs.empty()) {
      unsigned Reg = KilledRegs.pop_back_val();
      for (instr_iterator I = instr_end(), E = instr_begin(); I != E;) {
        if (!(--I)->addRegisterKilled(Reg, TRI, /* addIfNotFound= */ false))
          continue;
        if (TargetRegisterInfo::isVirtualRegister(Reg))
          LV->getVarInfo(Reg).Kills.push_back(I);
        DEBUG(dbgs() << "Restored terminator kill: " << *I);
        break;
      }
    }
    // Update relevant live-through information.
//.........这里部分代码省略.........