C++ iterator::isPseudo方法代码示例

MachineInstrBuilder
MipsInstrInfo::genInstrWithNewOpc(unsigned NewOpc,
                                  MachineBasicBlock::iterator I) const {
  MachineInstrBuilder MIB;

  // Certain branches have two forms: e.g beq $1, $zero, dest vs beqz $1, dest
  // Pick the zero form of the branch for readable assembly and for greater
  // branch distance in non-microMIPS mode.
  // Additional MIPSR6 does not permit the use of register $zero for compact
  // branches.
  // FIXME: Certain atomic sequences on mips64 generate 32bit references to
  // Mips::ZERO, which is incorrect. This test should be updated to use
  // Subtarget.getABI().GetZeroReg() when those atomic sequences and others
  // are fixed.
  int ZeroOperandPosition = -1;
  bool BranchWithZeroOperand = false;
  if (I->isBranch() && !I->isPseudo()) {
    auto TRI = I->getParent()->getParent()->getSubtarget().getRegisterInfo();
    ZeroOperandPosition = I->findRegisterUseOperandIdx(Mips::ZERO, false, TRI);
    BranchWithZeroOperand = ZeroOperandPosition != -1;
  }

  if (BranchWithZeroOperand) {
    switch (NewOpc) {
    case Mips::BEQC:
      NewOpc = Mips::BEQZC;
      break;
    case Mips::BNEC:
      NewOpc = Mips::BNEZC;
      break;
    case Mips::BGEC:
      NewOpc = Mips::BGEZC;
      break;
    case Mips::BLTC:
      NewOpc = Mips::BLTZC;
      break;
    case Mips::BEQC64:
      NewOpc = Mips::BEQZC64;
      break;
    case Mips::BNEC64:
      NewOpc = Mips::BNEZC64;
      break;
    }
  }

  MIB = BuildMI(*I->getParent(), I, I->getDebugLoc(), get(NewOpc));

  // For MIPSR6 JI*C requires an immediate 0 as an operand, JIALC(64) an
  // immediate 0 as an operand and requires the removal of it's %RA<imp-def>
  // implicit operand as copying the implicit operations of the instructio we're
  // looking at will give us the correct flags.
  if (NewOpc == Mips::JIC || NewOpc == Mips::JIALC || NewOpc == Mips::JIC64 ||
      NewOpc == Mips::JIALC64) {

    if (NewOpc == Mips::JIALC || NewOpc == Mips::JIALC64)
      MIB->RemoveOperand(0);

    for (unsigned J = 0, E = I->getDesc().getNumOperands(); J < E; ++J) {
      MIB.add(I->getOperand(J));
    }

    MIB.addImm(0);

  } else {
    for (unsigned J = 0, E = I->getDesc().getNumOperands(); J < E; ++J) {
      if (BranchWithZeroOperand && (unsigned)ZeroOperandPosition == J)
        continue;

      MIB.add(I->getOperand(J));
    }
  }

  MIB.copyImplicitOps(*I);

  MIB.setMemRefs(I->memoperands_begin(), I->memoperands_end());
  return MIB;
}

MachineInstrBuilder
MipsInstrInfo::genInstrWithNewOpc(unsigned NewOpc,
                                  MachineBasicBlock::iterator I) const {
  MachineInstrBuilder MIB;

  // Certain branches have two forms: e.g beq $1, $zero, dst vs beqz $1, dest
  // Pick the zero form of the branch for readable assembly and for greater
  // branch distance in non-microMIPS mode.
  // FIXME: Certain atomic sequences on mips64 generate 32bit references to
  // Mips::ZERO, which is incorrect. This test should be updated to use
  // Subtarget.getABI().GetZeroReg() when those atomic sequences and others
  // are fixed.
  bool BranchWithZeroOperand =
      (I->isBranch() && !I->isPseudo() && I->getOperand(1).isReg() &&
       (I->getOperand(1).getReg() == Mips::ZERO ||
        I->getOperand(1).getReg() == Mips::ZERO_64));

  if (BranchWithZeroOperand) {
    switch (NewOpc) {
    case Mips::BEQC:
      NewOpc = Mips::BEQZC;
      break;
    case Mips::BNEC:
      NewOpc = Mips::BNEZC;
      break;
    case Mips::BGEC:
      NewOpc = Mips::BGEZC;
      break;
    case Mips::BLTC:
      NewOpc = Mips::BLTZC;
      break;
    }
  }

  MIB = BuildMI(*I->getParent(), I, I->getDebugLoc(), get(NewOpc));

  // For MIPSR6 JI*C requires an immediate 0 as an operand, JIALC(64) an
  // immediate 0 as an operand and requires the removal of it's %RA<imp-def>
  // implicit operand as copying the implicit operations of the instructio we're
  // looking at will give us the correct flags.
  if (NewOpc == Mips::JIC || NewOpc == Mips::JIALC || NewOpc == Mips::JIC64 ||
      NewOpc == Mips::JIALC64) {

    if (NewOpc == Mips::JIALC || NewOpc == Mips::JIALC64)
      MIB->RemoveOperand(0);

    for (unsigned J = 0, E = I->getDesc().getNumOperands(); J < E; ++J) {
      MIB.addOperand(I->getOperand(J));
    }

    MIB.addImm(0);

 } else if (BranchWithZeroOperand) {
    // For MIPSR6 and microMIPS branches with an explicit zero operand, copy
    // everything after the zero.
     MIB.addOperand(I->getOperand(0));

    for (unsigned J = 2, E = I->getDesc().getNumOperands(); J < E; ++J) {
      MIB.addOperand(I->getOperand(J));
    }
  } else {
    // All other cases copy all other operands.
    for (unsigned J = 0, E = I->getDesc().getNumOperands(); J < E; ++J) {
      MIB.addOperand(I->getOperand(J));
    }
  }

  MIB.copyImplicitOps(*I);

  MIB.setMemRefs(I->memoperands_begin(), I->memoperands_end());
  return MIB;
}

bool PatmosInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
                                    MachineBasicBlock *&TBB,
                                    MachineBasicBlock *&FBB,
                                    SmallVectorImpl<MachineOperand> &Cond,
                                    bool AllowModify) const {
  // If the client does not want to only simplify the branch,
  // the output arguments must be initialized.
  assert(AllowModify || (TBB==0 && FBB==0 && Cond.size()==0));

  // Start from the bottom of the block and work up, examining the
  // terminator instructions.
  MachineBasicBlock::iterator I = MBB.end();

  while (I != MBB.begin()) {
    --I;

    if (I->isDebugValue() || I->isPseudo())
      continue;

    // Working from the bottom, when we see a non-terminator inst, we're done.
    if (!isUnpredicatedTerminator(I))
      break;

    // A terminator that isn't a (direct) branch can't easily be handled
    // by this analysis.
    if (!I->isBranch() || I->isIndirectBranch())
      return true;

    // Handle Unconditional branches
    if (!isPredicated(I)) {
      // fix instruction, if necessary
      if (!I->isUnconditionalBranch()) fixOpcodeForGuard(I);
      // TBB is used to indicate the unconditional destination.
      TBB = getBranchTarget(I);
      if (AllowModify) {
        // If the block has any instructions after an uncond branch, delete them.
        while (llvm::next(I) != MBB.end())
          llvm::next(I)->eraseFromParent();
      }
      continue;
    }

    // Handle conditional branches
    if (isPredicated(I)) {
      // fix instruction, if necessary
      if (!I->isConditionalBranch()) fixOpcodeForGuard(I);
      // we only treat the first conditional branch in a row
      if (Cond.size() > 0)
        return true;
      // Get branch condition
      int i = I->findFirstPredOperandIdx();
      assert(i != -1 );
      Cond.push_back(I->getOperand(i));   // reg
      Cond.push_back(I->getOperand(i+1)); // flag
      // We've processed an unconditional branch before,
      // the unconditional target goes to FBB now
      if (TBB) FBB = TBB;
      // target of conditional branch goes to TBB
      TBB = getBranchTarget(I);
      continue;
    }
    // we explicitly leave or continue.
    llvm_unreachable("AnalyzeBranch error.");
  }
  // left the loop? then we're done
  return false;
}