C++ SlotIndexes::insertMBBInMaps方法代码示例

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 nullptr;

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

  // Performance might be harmed on HW that implements branching using exec mask
  // where both sides of the branches are always executed.
  if (MF->getTarget().requiresStructuredCFG())
    return nullptr;

  // 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->getSubtarget().getInstrInfo();
  MachineBasicBlock *TBB = nullptr, *FBB = nullptr;
  SmallVector<MachineOperand, 4> Cond;
  if (TII->AnalyzeBranch(*this, TBB, FBB, Cond))
    return nullptr;

  // 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 nullptr;
  }

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

  LiveIntervals *LIS = P->getAnalysisIfAvailable<LiveIntervals>();
  SlotIndexes *Indexes = P->getAnalysisIfAvailable<SlotIndexes>();
  if (LIS)
    LIS->insertMBBInMaps(NMBB);
  else if (Indexes)
    Indexes->insertMBBInMaps(NMBB);

  // 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);
        }
      }
    }

  SmallVector<unsigned, 4> UsedRegs;
  if (LIS) {
    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)
          continue;

        unsigned Reg = OI->getReg();
        if (std::find(UsedRegs.begin(), UsedRegs.end(), Reg) == UsedRegs.end())
          UsedRegs.push_back(Reg);
      }
    }
  }

  ReplaceUsesOfBlockWith(Succ, NMBB);

  // If updateTerminator() removes instructions, we need to remove them from
  // SlotIndexes.
  SmallVector<MachineInstr*, 4> Terminators;
  if (Indexes) {
    for (instr_iterator I = getFirstInstrTerminator(), E = instr_end();
         I != E; ++I)
      Terminators.push_back(I);
//.........这里部分代码省略.........