X86InstrInfo.cpp

  } else if (i == 2) {
    OpcodeTablePtr = &RegOp2MemOpTable2;
  }
  
  // If table selected...
  if (OpcodeTablePtr) {
    // Find the Opcode to fuse
    DenseMap<unsigned*, unsigned>::iterator I =
      OpcodeTablePtr->find((unsigned*)MI->getOpcode());
    if (I != OpcodeTablePtr->end()) {
      if (isTwoAddrFold)
        NewMI = FuseTwoAddrInst(MF, I->second, MOs, MI, *this);
      else
        NewMI = FuseInst(MF, I->second, i, MOs, MI, *this);
      return NewMI;
    }
  }
  
  // No fusion 
  if (PrintFailedFusing)
    cerr << "We failed to fuse operand " << i << *MI;
  return NULL;
}


MachineInstr* X86InstrInfo::foldMemoryOperand(MachineFunction &MF,
                                              MachineInstr *MI,
                                        const SmallVectorImpl<unsigned> &Ops,
                                              int FrameIndex) const {
  // Check switch flag 
  if (NoFusing) return NULL;

  const MachineFrameInfo *MFI = MF.getFrameInfo();
  unsigned Alignment = MFI->getObjectAlignment(FrameIndex);
  // FIXME: Move alignment requirement into tables?
  if (Alignment < 16) {
    switch (MI->getOpcode()) {
    default: break;
    // Not always safe to fold movsd into these instructions since their load
    // folding variants expects the address to be 16 byte aligned.
    case X86::FsANDNPDrr:
    case X86::FsANDNPSrr:
    case X86::FsANDPDrr:
    case X86::FsANDPSrr:
    case X86::FsORPDrr:
    case X86::FsORPSrr:
    case X86::FsXORPDrr:
    case X86::FsXORPSrr:
      return NULL;
    }
  }

  if (Ops.size() == 2 && Ops[0] == 0 && Ops[1] == 1) {
    unsigned NewOpc = 0;
    switch (MI->getOpcode()) {
    default: return NULL;
    case X86::TEST8rr:  NewOpc = X86::CMP8ri; break;
    case X86::TEST16rr: NewOpc = X86::CMP16ri; break;
    case X86::TEST32rr: NewOpc = X86::CMP32ri; break;
    case X86::TEST64rr: NewOpc = X86::CMP64ri32; break;
    }
    // Change to CMPXXri r, 0 first.
    MI->setDesc(get(NewOpc));
    MI->getOperand(1).ChangeToImmediate(0);
  } else if (Ops.size() != 1)
    return NULL;

  SmallVector<MachineOperand,4> MOs;
  MOs.push_back(MachineOperand::CreateFI(FrameIndex));
  return foldMemoryOperand(MF, MI, Ops[0], MOs);
}

MachineInstr* X86InstrInfo::foldMemoryOperand(MachineFunction &MF,
                                              MachineInstr *MI,
                                        const SmallVectorImpl<unsigned> &Ops,
                                              MachineInstr *LoadMI) const {
  // Check switch flag 
  if (NoFusing) return NULL;

  // Determine the alignment of the load.
  unsigned Alignment = 0;
  if (LoadMI->hasOneMemOperand())
    Alignment = LoadMI->memoperands_begin()->getAlignment();

  // FIXME: Move alignment requirement into tables?
  if (Alignment < 16) {
    switch (MI->getOpcode()) {
    default: break;
    // Not always safe to fold movsd into these instructions since their load
    // folding variants expects the address to be 16 byte aligned.
    case X86::FsANDNPDrr:
    case X86::FsANDNPSrr:
    case X86::FsANDPDrr:
    case X86::FsANDPSrr:
    case X86::FsORPDrr:
    case X86::FsORPSrr:
    case X86::FsXORPDrr:
    case X86::FsXORPSrr:
      return NULL;
    }
  }

  if (Ops.size() == 2 && Ops[0] == 0 && Ops[1] == 1) {
    unsigned NewOpc = 0;
    switch (MI->getOpcode()) {
    default: return NULL;
    case X86::TEST8rr:  NewOpc = X86::CMP8ri; break;
    case X86::TEST16rr: NewOpc = X86::CMP16ri; break;
    case X86::TEST32rr: NewOpc = X86::CMP32ri; break;
    case X86::TEST64rr: NewOpc = X86::CMP64ri32; break;
    }
    // Change to CMPXXri r, 0 first.
    MI->setDesc(get(NewOpc));
    MI->getOperand(1).ChangeToImmediate(0);
  } else if (Ops.size() != 1)
    return NULL;

  SmallVector<MachineOperand,4> MOs;
  unsigned NumOps = LoadMI->getDesc().getNumOperands();
  for (unsigned i = NumOps - 4; i != NumOps; ++i)
    MOs.push_back(LoadMI->getOperand(i));
  return foldMemoryOperand(MF, MI, Ops[0], MOs);
}


bool X86InstrInfo::canFoldMemoryOperand(const MachineInstr *MI,
                                  const SmallVectorImpl<unsigned> &Ops) const {
  // Check switch flag 
  if (NoFusing) return 0;

  if (Ops.size() == 2 && Ops[0] == 0 && Ops[1] == 1) {
    switch (MI->getOpcode()) {
    default: return false;
    case X86::TEST8rr: 
    case X86::TEST16rr:
    case X86::TEST32rr:
    case X86::TEST64rr:
      return true;
    }
  }

  if (Ops.size() != 1)
    return false;

  unsigned OpNum = Ops[0];
  unsigned Opc = MI->getOpcode();
  unsigned NumOps = MI->getDesc().getNumOperands();
  bool isTwoAddr = NumOps > 1 &&
    MI->getDesc().getOperandConstraint(1, TOI::TIED_TO) != -1;

  // Folding a memory location into the two-address part of a two-address
  // instruction is different than folding it other places.  It requires
  // replacing the *two* registers with the memory location.
  const DenseMap<unsigned*, unsigned> *OpcodeTablePtr = NULL;
  if (isTwoAddr && NumOps >= 2 && OpNum < 2) { 
    OpcodeTablePtr = &RegOp2MemOpTable2Addr;
  } else if (OpNum == 0) { // If operand 0
    switch (Opc) {
    case X86::MOV16r0:
    case X86::MOV32r0:
    case X86::MOV64r0:
    case X86::MOV8r0:
      return true;
    default: break;
    }
    OpcodeTablePtr = &RegOp2MemOpTable0;
  } else if (OpNum == 1) {
    OpcodeTablePtr = &RegOp2MemOpTable1;
  } else if (OpNum == 2) {
    OpcodeTablePtr = &RegOp2MemOpTable2;
  }
  
  if (OpcodeTablePtr) {
    // Find the Opcode to fuse
    DenseMap<unsigned*, unsigned>::iterator I =
      OpcodeTablePtr->find((unsigned*)Opc);
    if (I != OpcodeTablePtr->end())
      return true;
  }
  return false;
}

bool X86InstrInfo::unfoldMemoryOperand(MachineFunction &MF, MachineInstr *MI,
                                unsigned Reg, bool UnfoldLoad, bool UnfoldStore,
                                 SmallVectorImpl<MachineInstr*> &NewMIs) const {
  DenseMap<unsigned*, std::pair<unsigned,unsigned> >::iterator I =
    MemOp2RegOpTable.find((unsigned*)MI->getOpcode());
  if (I == MemOp2RegOpTable.end())
    return false;
  unsigned Opc = I->second.first;
  unsigned Index = I->second.second & 0xf;
  bool FoldedLoad = I->second.second & (1 << 4);
  bool FoldedStore = I->second.second & (1 << 5);
  if (UnfoldLoad && !FoldedLoad)
    return false;
  UnfoldLoad &= FoldedLoad;
  if (UnfoldStore && !FoldedStore)
    return false;
  UnfoldStore &= FoldedStore;

  const TargetInstrDesc &TID = get(Opc);
  const TargetOperandInfo &TOI = TID.OpInfo[Index];
  const TargetRegisterClass *RC = TOI.isLookupPtrRegClass()
    ? getPointerRegClass() : RI.getRegClass(TOI.RegClass);
  SmallVector<MachineOperand,4> AddrOps;
  SmallVector<MachineOperand,2> BeforeOps;
  SmallVector<MachineOperand,2> AfterOps;
  SmallVector<MachineOperand,4> ImpOps;
  for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
    MachineOperand &Op = MI->getOperand(i);
    if (i >= Index && i < Index+4)
      AddrOps.push_back(Op);
    else if (Op.isReg() && Op.isImplicit())
      ImpOps.push_back(Op);
    else if (i < Index)
      BeforeOps.push_back(Op);
    else if (i > Index)
      AfterOps.push_back(Op);
  }

  // Emit the load instruction.
  if (UnfoldLoad) {
    loadRegFromAddr(MF, Reg, AddrOps, RC, NewMIs);
    if (UnfoldStore) {
      // Address operands cannot be marked isKill.
      for (unsigned i = 1; i != 5; ++i) {
        MachineOperand &MO = NewMIs[0]->getOperand(i);
        if (MO.isReg())
          MO.setIsKill(false);
      }
    }
  }

  // Emit the data processing instruction.
  MachineInstr *DataMI = MF.CreateMachineInstr(TID, true);
  MachineInstrBuilder MIB(DataMI);
  
  if (FoldedStore)
    MIB.addReg(Reg, true);
  for (unsigned i = 0, e = BeforeOps.size(); i != e; ++i)
    MIB = X86InstrAddOperand(MIB, BeforeOps[i]);
  if (FoldedLoad)
    MIB.addReg(Reg);
  for (unsigned i = 0, e = AfterOps.size(); i != e; ++i)
    MIB = X86InstrAddOperand(MIB, AfterOps[i]);
  for (unsigned i = 0, e = ImpOps.size(); i != e; ++i) {
    MachineOperand &MO = ImpOps[i];
    MIB.addReg(MO.getReg(), MO.isDef(), true, MO.isKill(), MO.isDead());
  }
  // Change CMP32ri r, 0 back to TEST32rr r, r, etc.
  unsigned NewOpc = 0;
  switch (DataMI->getOpcode()) {
  default: break;
  case X86::CMP64ri32:
  case X86::CMP32ri:
  case X86::CMP16ri:
  case X86::CMP8ri: {
    MachineOperand &MO0 = DataMI->getOperand(0);
    MachineOperand &MO1 = DataMI->getOperand(1);
    if (MO1.getImm() == 0) {
      switch (DataMI->getOpcode()) {
      default: break;
      case X86::CMP64ri32: NewOpc = X86::TEST64rr; break;
      case X86::CMP32ri:   NewOpc = X86::TEST32rr; break;
      case X86::CMP16ri:   NewOpc = X86::TEST16rr; break;
      case X86::CMP8ri:    NewOpc = X86::TEST8rr; break;
      }
      DataMI->setDesc(get(NewOpc));
      MO1.ChangeToRegister(MO0.getReg(), false);
    }
  }
  }
  NewMIs.push_back(DataMI);

  // Emit the store instruction.
  if (UnfoldStore) {
    const TargetOperandInfo &DstTOI = TID.OpInfo[0];
    const TargetRegisterClass *DstRC = DstTOI.isLookupPtrRegClass()
      ? getPointerRegClass() : RI.getRegClass(DstTOI.RegClass);
    storeRegToAddr(MF, Reg, true, AddrOps, DstRC, NewMIs);
  }

  return true;
}

bool
X86InstrInfo::unfoldMemoryOperand(SelectionDAG &DAG, SDNode *N,
                                     SmallVectorImpl<SDNode*> &NewNodes) const {
  if (!N->isMachineOpcode())
    return false;

  DenseMap<unsigned*, std::pair<unsigned,unsigned> >::iterator I =
    MemOp2RegOpTable.find((unsigned*)N->getMachineOpcode());
  if (I == MemOp2RegOpTable.end())
    return false;
  unsigned Opc = I->second.first;
  unsigned Index = I->second.second & 0xf;
  bool FoldedLoad = I->second.second & (1 << 4);
  bool FoldedStore = I->second.second & (1 << 5);
  const TargetInstrDesc &TID = get(Opc);
  const TargetOperandInfo &TOI = TID.OpInfo[Index];
  const TargetRegisterClass *RC = TOI.isLookupPtrRegClass()
    ? getPointerRegClass() : RI.getRegClass(TOI.RegClass);
  std::vector<SDValue> AddrOps;
  std::vector<SDValue> BeforeOps;
  std::vector<SDValue> AfterOps;
  unsigned NumOps = N->getNumOperands();
  for (unsigned i = 0; i != NumOps-1; ++i) {
    SDValue Op = N->getOperand(i);
    if (i >= Index && i < Index+4)
      AddrOps.push_back(Op);
    else if (i < Index)
      BeforeOps.push_back(Op);
    else if (i > Index)
      AfterOps.push_back(Op);
  }
  SDValue Chain = N->getOperand(NumOps-1);
  AddrOps.push_back(Chain);

  // Emit the load instruction.
  SDNode *Load = 0;
  const MachineFunction &MF = DAG.getMachineFunction();
  if (FoldedLoad) {
    MVT VT = *RC->vt_begin();
    bool isAligned = (RI.getStackAlignment() >= 16) ||
      RI.needsStackRealignment(MF);
    Load = DAG.getTargetNode(getLoadRegOpcode(RC, isAligned),
                             VT, MVT::Other,
                             &AddrOps[0], AddrOps.size());
    NewNodes.push_back(Load);
  }

  // Emit the data processing instruction.
  std::vector<MVT> VTs;
  const TargetRegisterClass *DstRC = 0;
  if (TID.getNumDefs() > 0) {
    const TargetOperandInfo &DstTOI = TID.OpInfo[0];
    DstRC = DstTOI.isLookupPtrRegClass()
      ? getPointerRegClass() : RI.getRegClass(DstTOI.RegClass);
    VTs.push_back(*DstRC->vt_begin());
  }
  for (unsigned i = 0, e = N->getNumValues(); i != e; ++i) {
    MVT VT = N->getValueType(i);
    if (VT != MVT::Other && i >= (unsigned)TID.getNumDefs())
      VTs.push_back(VT);
  }
  if (Load)
    BeforeOps.push_back(SDValue(Load, 0));
  std::copy(AfterOps.begin(), AfterOps.end(), std::back_inserter(BeforeOps));
  SDNode *NewNode= DAG.getTargetNode(Opc, VTs, &BeforeOps[0], BeforeOps.size());
  NewNodes.push_back(NewNode);

  // Emit the store instruction.
  if (FoldedStore) {
    AddrOps.pop_back();
    AddrOps.push_back(SDValue(NewNode, 0));
    AddrOps.push_back(Chain);
    bool isAligned = (RI.getStackAlignment() >= 16) ||
      RI.needsStackRealignment(MF);
    SDNode *Store = DAG.getTargetNode(getStoreRegOpcode(DstRC, isAligned),
                                      MVT::Other, &AddrOps[0], AddrOps.size());
    NewNodes.push_back(Store);
  }

  return true;
}

unsigned X86InstrInfo::getOpcodeAfterMemoryUnfold(unsigned Opc,
                                      bool UnfoldLoad, bool UnfoldStore) const {
  DenseMap<unsigned*, std::pair<unsigned,unsigned> >::iterator I =
    MemOp2RegOpTable.find((unsigned*)Opc);
  if (I == MemOp2RegOpTable.end())
    return 0;
  bool FoldedLoad = I->second.second & (1 << 4);
  bool FoldedStore = I->second.second & (1 << 5);
  if (UnfoldLoad && !FoldedLoad)
    return 0;
  if (UnfoldStore && !FoldedStore)
    return 0;
  return I->second.first;
}

bool X86InstrInfo::BlockHasNoFallThrough(const MachineBasicBlock &MBB) const {
  if (MBB.empty()) return false;
  
  switch (MBB.back().getOpcode()) {
  case X86::TCRETURNri:
  case X86::TCRETURNdi:
  case X86::RET:     // Return.
  case X86::RETI:
  case X86::TAILJMPd:
  case X86::TAILJMPr:
  case X86::TAILJMPm:
  case X86::JMP:     // Uncond branch.
  case X86::JMP32r:  // Indirect branch.
  case X86::JMP64r:  // Indirect branch (64-bit).
  case X86::JMP32m:  // Indirect branch through mem.
  case X86::JMP64m:  // Indirect branch through mem (64-bit).
    return true;
  default: return false;
  }
}

bool X86InstrInfo::
ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const {
  assert(Cond.size() == 1 && "Invalid X86 branch condition!");
  X86::CondCode CC = static_cast<X86::CondCode>(Cond[0].getImm());
  if (CC == X86::COND_NE_OR_P || CC == X86::COND_NP_OR_E)
    return true;
  Cond[0].setImm(GetOppositeBranchCondition(CC));
  return false;
}

const TargetRegisterClass *X86InstrInfo::getPointerRegClass() const {
  const X86Subtarget *Subtarget = &TM.getSubtarget<X86Subtarget>();
  if (Subtarget->is64Bit())
    return &X86::GR64RegClass;
  else
    return &X86::GR32RegClass;
}

unsigned X86InstrInfo::sizeOfImm(const TargetInstrDesc *Desc) {
  switch (Desc->TSFlags & X86II::ImmMask) {
  case X86II::Imm8:   return 1;
  case X86II::Imm16:  return 2;
  case X86II::Imm32:  return 4;
  case X86II::Imm64:  return 8;
  default: assert(0 && "Immediate size not set!");
    return 0;
  }
}

/// isX86_64ExtendedReg - Is the MachineOperand a x86-64 extended register?
/// e.g. r8, xmm8, etc.
bool X86InstrInfo::isX86_64ExtendedReg(const MachineOperand &MO) {
  if (!MO.isReg()) return false;
  switch (MO.getReg()) {
  default: break;
  case X86::R8:    case X86::R9:    case X86::R10:   case X86::R11:
  case X86::R12:   case X86::R13:   case X86::R14:   case X86::R15:
  case X86::R8D:   case X86::R9D:   case X86::R10D:  case X86::R11D:
  case X86::R12D:  case X86::R13D:  case X86::R14D:  case X86::R15D:
  case X86::R8W:   case X86::R9W:   case X86::R10W:  case X86::R11W:
  case X86::R12W:  case X86::R13W:  case X86::R14W:  case X86::R15W:
  case X86::R8B:   case X86::R9B:   case X86::R10B:  case X86::R11B:
  case X86::R12B:  case X86::R13B:  case X86::R14B:  case X86::R15B:
  case X86::XMM8:  case X86::XMM9:  case X86::XMM10: case X86::XMM11:
  case X86::XMM12: case X86::XMM13: case X86::XMM14: case X86::XMM15:
    return true;
  }
  return false;
}


/// determineREX - Determine if the MachineInstr has to be encoded with a X86-64
/// REX prefix which specifies 1) 64-bit instructions, 2) non-default operand
/// size, and 3) use of X86-64 extended registers.
unsigned X86InstrInfo::determineREX(const MachineInstr &MI) {
  unsigned REX = 0;
  const TargetInstrDesc &Desc = MI.getDesc();

  // Pseudo instructions do not need REX prefix byte.
  if ((Desc.TSFlags & X86II::FormMask) == X86II::Pseudo)
    return 0;
  if (Desc.TSFlags & X86II::REX_W)
    REX |= 1 << 3;

  unsigned NumOps = Desc.getNumOperands();
  if (NumOps) {
    bool isTwoAddr = NumOps > 1 &&
      Desc.getOperandConstraint(1, TOI::TIED_TO) != -1;

    // If it accesses SPL, BPL, SIL, or DIL, then it requires a 0x40 REX prefix.
    unsigned i = isTwoAddr ? 1 : 0;
    for (unsigned e = NumOps; i != e; ++i) {
      const MachineOperand& MO = MI.getOperand(i);
      if (MO.isReg()) {
        unsigned Reg = MO.getReg();
        if (isX86_64NonExtLowByteReg(Reg))
          REX |= 0x40;
      }
    }

    switch (Desc.TSFlags & X86II::FormMask) {
    case X86II::MRMInitReg:
      if (isX86_64ExtendedReg(MI.getOperand(0)))
        REX |= (1 << 0) | (1 << 2);
      break;
    case X86II::MRMSrcReg: {
      if (isX86_64ExtendedReg(MI.getOperand(0)))
        REX |= 1 << 2;
      i = isTwoAddr ? 2 : 1;
      for (unsigned e = NumOps; i != e; ++i) {
        const MachineOperand& MO = MI.getOperand(i);
        if (isX86_64ExtendedReg(MO))
          REX |= 1 << 0;
      }
      break;
    }
    case X86II::MRMSrcMem: {
      if (isX86_64ExtendedReg(MI.getOperand(0)))
        REX |= 1 << 2;
      unsigned Bit = 0;
      i = isTwoAddr ? 2 : 1;
      for (; i != NumOps; ++i) {
        const MachineOperand& MO = MI.getOperand(i);
        if (MO.isReg()) {
          if (isX86_64ExtendedReg(MO))
            REX |= 1 << Bit;
          Bit++;
        }
      }
      break;
    }
    case X86II::MRM0m: case X86II::MRM1m:
    case X86II::MRM2m: case X86II::MRM3m:
    case X86II::MRM4m: case X86II::MRM5m:
    case X86II::MRM6m: case X86II::MRM7m:
    case X86II::MRMDestMem: {
      unsigned e = isTwoAddr ? 5 : 4;
      i = isTwoAddr ? 1 : 0;
      if (NumOps > e && isX86_64ExtendedReg(MI.getOperand(e)))
        REX |= 1 << 2;
      unsigned Bit = 0;
      for (; i != e; ++i) {
        const MachineOperand& MO = MI.getOperand(i);
        if (MO.isReg()) {
          if (isX86_64ExtendedReg(MO))
            REX |= 1 << Bit;
          Bit++;
        }
      }
      break;
    }
    default: {
      if (isX86_64ExtendedReg(MI.getOperand(0)))
        REX |= 1 << 0;
      i = isTwoAddr ? 2 : 1;
      for (unsigned e = NumOps; i != e; ++i) {
        const MachineOperand& MO = MI.getOperand(i);
        if (isX86_64ExtendedReg(MO))
          REX |= 1 << 2;
      }
      break;
    }
    }
  }
  return REX;
}

/// sizePCRelativeBlockAddress - This method returns the size of a PC
/// relative block address instruction
///
static unsigned sizePCRelativeBlockAddress() {
  return 4;
}

/// sizeGlobalAddress - Give the size of the emission of this global address
///
static unsigned sizeGlobalAddress(bool dword) {
  return dword ? 8 : 4;
}

/// sizeConstPoolAddress - Give the size of the emission of this constant
/// pool address
///
static unsigned sizeConstPoolAddress(bool dword) {
  return dword ? 8 : 4;
}

/// sizeExternalSymbolAddress - Give the size of the emission of this external
/// symbol
///
static unsigned sizeExternalSymbolAddress(bool dword) {
  return dword ? 8 : 4;
}

/// sizeJumpTableAddress - Give the size of the emission of this jump
/// table address
///
static unsigned sizeJumpTableAddress(bool dword) {
  return dword ? 8 : 4;
}

static unsigned sizeConstant(unsigned Size) {
  return Size;
}

static unsigned sizeRegModRMByte(){
  return 1;
}

static unsigned sizeSIBByte(){
  return 1;
}

static unsigned getDisplacementFieldSize(const MachineOperand *RelocOp) {
  unsigned FinalSize = 0;
  // If this is a simple integer displacement that doesn't require a relocation.
  if (!RelocOp) {
    FinalSize += sizeConstant(4);
    return FinalSize;
  }
  
  // Otherwise, this is something that requires a relocation.
  if (RelocOp->isGlobal()) {
    FinalSize += sizeGlobalAddress(false);
  } else if (RelocOp->isCPI()) {
    FinalSize += sizeConstPoolAddress(false);
  } else if (RelocOp->isJTI()) {
    FinalSize += sizeJumpTableAddress(false);
  } else {
    assert(0 && "Unknown value to relocate!");
  }
  return FinalSize;
}

static unsigned getMemModRMByteSize(const MachineInstr &MI, unsigned Op,
                                    bool IsPIC, bool Is64BitMode) {
  const MachineOperand &Op3 = MI.getOperand(Op+3);
  int DispVal = 0;
  const MachineOperand *DispForReloc = 0;
  unsigned FinalSize = 0;
  
  // Figure out what sort of displacement we have to handle here.
  if (Op3.isGlobal()) {
    DispForReloc = &Op3;
  } else if (Op3.isCPI()) {
    if (Is64BitMode || IsPIC) {
      DispForReloc = &Op3;
    } else {
      DispVal = 1;
    }
  } else if (Op3.isJTI()) {
    if (Is64BitMode || IsPIC) {
      DispForReloc = &Op3;
    } else {
      DispVal = 1; 
    }
  } else {
    DispVal = 1;
  }

  const MachineOperand &Base     = MI.getOperand(Op);
  const MachineOperand &IndexReg = MI.getOperand(Op+2);

  unsigned BaseReg = Base.getReg();

  // Is a SIB byte needed?
  if (IndexReg.getReg() == 0 &&
      (BaseReg == 0 || X86RegisterInfo::getX86RegNum(BaseReg) != N86::ESP)) {
    if (BaseReg == 0) {  // Just a displacement?
      // Emit special case [disp32] encoding
      ++FinalSize; 
      FinalSize += getDisplacementFieldSize(DispForReloc);
    } else {
      unsigned BaseRegNo = X86RegisterInfo::getX86RegNum(BaseReg);
      if (!DispForReloc && DispVal == 0 && BaseRegNo != N86::EBP) {
        // Emit simple indirect register encoding... [EAX] f.e.
        ++FinalSize;
      // Be pessimistic and assume it's a disp32, not a disp8
      } else {
        // Emit the most general non-SIB encoding: [REG+disp32]
        ++FinalSize;
        FinalSize += getDisplacementFieldSize(DispForReloc);
      }
    }

  } else {  // We need a SIB byte, so start by outputting the ModR/M byte first
    assert(IndexReg.getReg() != X86::ESP &&
           IndexReg.getReg() != X86::RSP && "Cannot use ESP as index reg!");

    bool ForceDisp32 = false;
    if (BaseReg == 0 || DispForReloc) {
      // Emit the normal disp32 encoding.
      ++FinalSize;
      ForceDisp32 = true;
    } else {
      ++FinalSize;
    }

    FinalSize += sizeSIBByte();

    // Do we need to output a displacement?
    if (DispVal != 0 || ForceDisp32) {
      FinalSize += getDisplacementFieldSize(DispForReloc);
    }
  }
  return FinalSize;
}


static unsigned GetInstSizeWithDesc(const MachineInstr &MI,
                                    const TargetInstrDesc *Desc,
                                    bool IsPIC, bool Is64BitMode) {
  
  unsigned Opcode = Desc->Opcode;
  unsigned FinalSize = 0;

  // Emit the lock opcode prefix as needed.
  if (Desc->TSFlags & X86II::LOCK) ++FinalSize;

  // Emit segment overrid opcode prefix as needed.
  switch (Desc->TSFlags & X86II::SegOvrMask) {
  case X86II::FS:
  case X86II::GS:
   ++FinalSize;
   break;
  default: assert(0 && "Invalid segment!");
  case 0: break;  // No segment override!
  }

  // Emit the repeat opcode prefix as needed.
  if ((Desc->TSFlags & X86II::Op0Mask) == X86II::REP) ++FinalSize;

  // Emit the operand size opcode prefix as needed.
  if (Desc->TSFlags & X86II::OpSize) ++FinalSize;

  // Emit the address size opcode prefix as needed.
  if (Desc->TSFlags & X86II::AdSize) ++FinalSize;

  bool Need0FPrefix = false;
  switch (Desc->TSFlags & X86II::Op0Mask) {
  case X86II::TB:  // Two-byte opcode prefix
  case X86II::T8:  // 0F 38
  case X86II::TA:  // 0F 3A
    Need0FPrefix = true;
    break;
  case X86II::REP: break; // already handled.
  case X86II::XS:   // F3 0F
    ++FinalSize;
    Need0FPrefix = true;
    break;
  case X86II::XD:   // F2 0F
    ++FinalSize;
    Need0FPrefix = true;
    break;
  case X86II::D8: case X86II::D9: case X86II::DA: case X86II::DB:
  case X86II::DC: case X86II::DD: case X86II::DE: case X86II::DF:
    ++FinalSize;
    break; // Two-byte opcode prefix
  default: assert(0 && "Invalid prefix!");
  case 0: break;  // No prefix!
  }

  if (Is64BitMode) {
    // REX prefix
    unsigned REX = X86InstrInfo::determineREX(MI);
    if (REX)
      ++FinalSize;
  }

  // 0x0F escape code must be emitted just before the opcode.
  if (Need0FPrefix)
    ++FinalSize;

  switch (Desc->TSFlags & X86II::Op0Mask) {
  case X86II::T8:  // 0F 38
    ++FinalSize;
    break;
  case X86II::TA:    // 0F 3A
    ++FinalSize;
    break;
  }

  // If this is a two-address instruction, skip one of the register operands.
  unsigned NumOps = Desc->getNumOperands();
  unsigned CurOp = 0;
  if (NumOps > 1 && Desc->getOperandConstraint(1, TOI::TIED_TO) != -1)
    CurOp++;

  switch (Desc->TSFlags & X86II::FormMask) {
  default: assert(0 && "Unknown FormMask value in X86 MachineCodeEmitter!");
  case X86II::Pseudo:
    // Remember the current PC offset, this is the PIC relocation
    // base address.
    switch (Opcode) {
    default: 
      break;
    case TargetInstrInfo::INLINEASM: {
      const MachineFunction *MF = MI.getParent()->getParent();
      const char *AsmStr = MI.getOperand(0).getSymbolName();
      const TargetAsmInfo* AI = MF->getTarget().getTargetAsmInfo();
      FinalSize += AI->getInlineAsmLength(AsmStr);
      break;
    }
    case TargetInstrInfo::DBG_LABEL:
    case TargetInstrInfo::EH_LABEL:
      break;
    case TargetInstrInfo::IMPLICIT_DEF:
    case TargetInstrInfo::DECLARE:
    case X86::DWARF_LOC:
    case X86::FP_REG_KILL:
      break;
    case X86::MOVPC32r: {
      // This emits the "call" portion of this pseudo instruction.
      ++FinalSize;
      FinalSize += sizeConstant(X86InstrInfo::sizeOfImm(Desc));
      break;
    }
    case X86::TLS_tp:
    case X86::TLS_gs_ri:
      FinalSize += 2;
      FinalSize += sizeGlobalAddress(false);
      break;
    }
    CurOp = NumOps;
    break;
  case X86II::RawFrm:
    ++FinalSize;

    if (CurOp != NumOps) {
      const MachineOperand &MO = MI.getOperand(CurOp++);
      if (MO.isMBB()) {
        FinalSize += sizePCRelativeBlockAddress();
      } else if (MO.isGlobal()) {
        FinalSize += sizeGlobalAddress(false);
      } else if (MO.isSymbol()) {
        FinalSize += sizeExternalSymbolAddress(false);
      } else if (MO.isImm()) {
        FinalSize += sizeConstant(X86InstrInfo::sizeOfImm(Desc));
      } else {
        assert(0 && "Unknown RawFrm operand!");
      }
    }
    break;

  case X86II::AddRegFrm:
    ++FinalSize;
    ++CurOp;
    
    if (CurOp != NumOps) {
      const MachineOperand &MO1 = MI.getOperand(CurOp++);
      unsigned Size = X86InstrInfo::sizeOfImm(Desc);
      if (MO1.isImm())
        FinalSize += sizeConstant(Size);
      else {
        bool dword = false;
        if (Opcode == X86::MOV64ri)
          dword = true; 
        if (MO1.isGlobal()) {
          FinalSize += sizeGlobalAddress(dword);
        } else if (MO1.isSymbol())
          FinalSize += sizeExternalSymbolAddress(dword);
        else if (MO1.isCPI())
          FinalSize += sizeConstPoolAddress(dword);
        else if (MO1.isJTI())
          FinalSize += sizeJumpTableAddress(dword);
      }
    }
    break;

  case X86II::MRMDestReg: {
    ++FinalSize; 
    FinalSize += sizeRegModRMByte();
    CurOp += 2;
    if (CurOp != NumOps) {
      ++CurOp;
      FinalSize += sizeConstant(X86InstrInfo::sizeOfImm(Desc));
    }
    break;
  }
  case X86II::MRMDestMem: {
    ++FinalSize;
    FinalSize += getMemModRMByteSize(MI, CurOp, IsPIC, Is64BitMode);
    CurOp += 5;
    if (CurOp != NumOps) {
      ++CurOp;
      FinalSize += sizeConstant(X86InstrInfo::sizeOfImm(Desc));
    }
    break;
  }

  case X86II::MRMSrcReg:
    ++FinalSize;
    FinalSize += sizeRegModRMByte();
    CurOp += 2;
    if (CurOp != NumOps) {
      ++CurOp;
      FinalSize += sizeConstant(X86InstrInfo::sizeOfImm(Desc));
    }
    break;

  case X86II::MRMSrcMem: {

    ++FinalSize;
    FinalSize += getMemModRMByteSize(MI, CurOp+1, IsPIC, Is64BitMode);
    CurOp += 5;
    if (CurOp != NumOps) {
      ++CurOp;
      FinalSize += sizeConstant(X86InstrInfo::sizeOfImm(Desc));
    }
    break;
  }

  case X86II::MRM0r: case X86II::MRM1r:
  case X86II::MRM2r: case X86II::MRM3r:
  case X86II::MRM4r: case X86II::MRM5r:
  case X86II::MRM6r: case X86II::MRM7r:
    ++FinalSize;
    ++CurOp;
    FinalSize += sizeRegModRMByte();

    if (CurOp != NumOps) {
      const MachineOperand &MO1 = MI.getOperand(CurOp++);
      unsigned Size = X86InstrInfo::sizeOfImm(Desc);
      if (MO1.isImm())
        FinalSize += sizeConstant(Size);
      else {
        bool dword = false;
        if (Opcode == X86::MOV64ri32)
          dword = true;
        if (MO1.isGlobal()) {
          FinalSize += sizeGlobalAddress(dword);
        } else if (MO1.isSymbol())
          FinalSize += sizeExternalSymbolAddress(dword);
        else if (MO1.isCPI())
          FinalSize += sizeConstPoolAddress(dword);
        else if (MO1.isJTI())
          FinalSize += sizeJumpTableAddress(dword);
      }
    }
    break;

  case X86II::MRM0m: case X86II::MRM1m:
  case X86II::MRM2m: case X86II::MRM3m:
  case X86II::MRM4m: case X86II::MRM5m:
  case X86II::MRM6m: case X86II::MRM7m: {
    
    ++FinalSize;
    FinalSize += getMemModRMByteSize(MI, CurOp, IsPIC, Is64BitMode);
    CurOp += 4;

    if (CurOp != NumOps) {
      const MachineOperand &MO = MI.getOperand(CurOp++);
      unsigned Size = X86InstrInfo::sizeOfImm(Desc);
      if (MO.isImm())
        FinalSize += sizeConstant(Size);
      else {
        bool dword = false;
        if (Opcode == X86::MOV64mi32)
          dword = true;
        if (MO.isGlobal()) {
          FinalSize += sizeGlobalAddress(dword);
        } else if (MO.isSymbol())
          FinalSize += sizeExternalSymbolAddress(dword);
        else if (MO.isCPI())
          FinalSize += sizeConstPoolAddress(dword);
        else if (MO.isJTI())
          FinalSize += sizeJumpTableAddress(dword);
      }
    }
    break;
  }

  case X86II::MRMInitReg:
    ++FinalSize;
    // Duplicate register, used by things like MOV8r0 (aka xor reg,reg).
    FinalSize += sizeRegModRMByte();
    ++CurOp;
    break;
  }

  if (!Desc->isVariadic() && CurOp != NumOps) {
    cerr << "Cannot determine size: ";
    MI.dump();
    cerr << '\n';
    abort();
  }
  

  return FinalSize;
}


unsigned X86InstrInfo::GetInstSizeInBytes(const MachineInstr *MI) const {
  const TargetInstrDesc &Desc = MI->getDesc();
  bool IsPIC = (TM.getRelocationModel() == Reloc::PIC_);
  bool Is64BitMode = TM.getSubtargetImpl()->is64Bit();
  unsigned Size = GetInstSizeWithDesc(*MI, &Desc, IsPIC, Is64BitMode);
  if (Desc.getOpcode() == X86::MOVPC32r) {
    Size += GetInstSizeWithDesc(*MI, &get(X86::POP32r), IsPIC, Is64BitMode);
  }
  return Size;
}

/// getGlobalBaseReg - Return a virtual register initialized with the
/// the global base register value. Output instructions required to
/// initialize the register in the function entry block, if necessary.
///
unsigned X86InstrInfo::getGlobalBaseReg(MachineFunction *MF) const {
  assert(!TM.getSubtarget<X86Subtarget>().is64Bit() &&
         "X86-64 PIC uses RIP relative addressing");

  X86MachineFunctionInfo *X86FI = MF->getInfo<X86MachineFunctionInfo>();
  unsigned GlobalBaseReg = X86FI->getGlobalBaseReg();
  if (GlobalBaseReg != 0)
    return GlobalBaseReg;

  // Insert the set of GlobalBaseReg into the first MBB of the function