X86InstrInfo.cpp

}

/// convertToThreeAddress - This method must be implemented by targets that
/// set the M_CONVERTIBLE_TO_3_ADDR flag.  When this flag is set, the target
/// may be able to convert a two-address instruction into a true
/// three-address instruction on demand.  This allows the X86 target (for
/// example) to convert ADD and SHL instructions into LEA instructions if they
/// would require register copies due to two-addressness.
///
/// This method returns a null pointer if the transformation cannot be
/// performed, otherwise it returns the new instruction.
///
MachineInstr *
X86InstrInfo::convertToThreeAddress(MachineFunction::iterator &MFI,
                                    MachineBasicBlock::iterator &MBBI,
                                    LiveVariables *LV) const {
  MachineInstr *MI = MBBI;
  MachineFunction &MF = *MI->getParent()->getParent();
  // All instructions input are two-addr instructions.  Get the known operands.
  unsigned Dest = MI->getOperand(0).getReg();
  unsigned Src = MI->getOperand(1).getReg();
  bool isDead = MI->getOperand(0).isDead();
  bool isKill = MI->getOperand(1).isKill();

  MachineInstr *NewMI = NULL;
  // FIXME: 16-bit LEA's are really slow on Athlons, but not bad on P4's.  When
  // we have better subtarget support, enable the 16-bit LEA generation here.
  bool DisableLEA16 = true;

  unsigned MIOpc = MI->getOpcode();
  switch (MIOpc) {
  case X86::SHUFPSrri: {
    assert(MI->getNumOperands() == 4 && "Unknown shufps instruction!");
    if (!TM.getSubtarget<X86Subtarget>().hasSSE2()) return 0;
    
    unsigned B = MI->getOperand(1).getReg();
    unsigned C = MI->getOperand(2).getReg();
    if (B != C) return 0;
    unsigned A = MI->getOperand(0).getReg();
    unsigned M = MI->getOperand(3).getImm();
    NewMI = BuildMI(MF, get(X86::PSHUFDri)).addReg(A, true, false, false, isDead)
      .addReg(B, false, false, isKill).addImm(M);
    break;
  }
  case X86::SHL64ri: {
    assert(MI->getNumOperands() >= 3 && "Unknown shift instruction!");
    // NOTE: LEA doesn't produce flags like shift does, but LLVM never uses
    // the flags produced by a shift yet, so this is safe.
    unsigned ShAmt = MI->getOperand(2).getImm();
    if (ShAmt == 0 || ShAmt >= 4) return 0;

    NewMI = BuildMI(MF, get(X86::LEA64r)).addReg(Dest, true, false, false, isDead)
      .addReg(0).addImm(1 << ShAmt).addReg(Src, false, false, isKill).addImm(0);
    break;
  }
  case X86::SHL32ri: {
    assert(MI->getNumOperands() >= 3 && "Unknown shift instruction!");
    // NOTE: LEA doesn't produce flags like shift does, but LLVM never uses
    // the flags produced by a shift yet, so this is safe.
    unsigned ShAmt = MI->getOperand(2).getImm();
    if (ShAmt == 0 || ShAmt >= 4) return 0;

    unsigned Opc = TM.getSubtarget<X86Subtarget>().is64Bit() ?
      X86::LEA64_32r : X86::LEA32r;
    NewMI = BuildMI(MF, get(Opc)).addReg(Dest, true, false, false, isDead)
      .addReg(0).addImm(1 << ShAmt)
      .addReg(Src, false, false, isKill).addImm(0);
    break;
  }
  case X86::SHL16ri: {
    assert(MI->getNumOperands() >= 3 && "Unknown shift instruction!");
    // NOTE: LEA doesn't produce flags like shift does, but LLVM never uses
    // the flags produced by a shift yet, so this is safe.
    unsigned ShAmt = MI->getOperand(2).getImm();
    if (ShAmt == 0 || ShAmt >= 4) return 0;

    if (DisableLEA16) {
      // If 16-bit LEA is disabled, use 32-bit LEA via subregisters.
      MachineRegisterInfo &RegInfo = MFI->getParent()->getRegInfo();
      unsigned Opc = TM.getSubtarget<X86Subtarget>().is64Bit()
        ? X86::LEA64_32r : X86::LEA32r;
      unsigned leaInReg = RegInfo.createVirtualRegister(&X86::GR32RegClass);
      unsigned leaOutReg = RegInfo.createVirtualRegister(&X86::GR32RegClass);
            
      // Build and insert into an implicit UNDEF value. This is OK because
      // well be shifting and then extracting the lower 16-bits. 
      BuildMI(*MFI, MBBI, get(X86::IMPLICIT_DEF), leaInReg);      
      MachineInstr *InsMI =  BuildMI(*MFI, MBBI, get(X86::INSERT_SUBREG),leaInReg)
        .addReg(leaInReg).addReg(Src, false, false, isKill)
        .addImm(X86::SUBREG_16BIT);
      
      NewMI = BuildMI(*MFI, MBBI, get(Opc), leaOutReg).addReg(0).addImm(1 << ShAmt)
        .addReg(leaInReg, false, false, true).addImm(0);
      
      MachineInstr *ExtMI = BuildMI(*MFI, MBBI, get(X86::EXTRACT_SUBREG))
        .addReg(Dest, true, false, false, isDead)
        .addReg(leaOutReg, false, false, true).addImm(X86::SUBREG_16BIT);
      if (LV) {
        // Update live variables
        LV->getVarInfo(leaInReg).Kills.push_back(NewMI);
        LV->getVarInfo(leaOutReg).Kills.push_back(ExtMI);
        if (isKill)
          LV->replaceKillInstruction(Src, MI, InsMI);
        if (isDead)
          LV->replaceKillInstruction(Dest, MI, ExtMI);
      }
      return ExtMI;
    } else {
      NewMI = BuildMI(MF, get(X86::LEA16r)).addReg(Dest, true, false, false, isDead)
        .addReg(0).addImm(1 << ShAmt)
        .addReg(Src, false, false, isKill).addImm(0);
    }
    break;
  }
  default: {
    // The following opcodes also sets the condition code register(s). Only
    // convert them to equivalent lea if the condition code register def's
    // are dead!
    if (hasLiveCondCodeDef(MI))
      return 0;

    bool is64Bit = TM.getSubtarget<X86Subtarget>().is64Bit();
    switch (MIOpc) {
    default: return 0;
    case X86::INC64r:
    case X86::INC32r:
    case X86::INC64_32r: {
      assert(MI->getNumOperands() >= 2 && "Unknown inc instruction!");
      unsigned Opc = MIOpc == X86::INC64r ? X86::LEA64r
        : (is64Bit ? X86::LEA64_32r : X86::LEA32r);
      NewMI = addRegOffset(BuildMI(MF, get(Opc))
                           .addReg(Dest, true, false, false, isDead),
                           Src, isKill, 1);
      break;
    }
    case X86::INC16r:
    case X86::INC64_16r:
      if (DisableLEA16) return 0;
      assert(MI->getNumOperands() >= 2 && "Unknown inc instruction!");
      NewMI = addRegOffset(BuildMI(MF, get(X86::LEA16r))
                           .addReg(Dest, true, false, false, isDead),
                           Src, isKill, 1);
      break;
    case X86::DEC64r:
    case X86::DEC32r:
    case X86::DEC64_32r: {
      assert(MI->getNumOperands() >= 2 && "Unknown dec instruction!");
      unsigned Opc = MIOpc == X86::DEC64r ? X86::LEA64r
        : (is64Bit ? X86::LEA64_32r : X86::LEA32r);
      NewMI = addRegOffset(BuildMI(MF, get(Opc))
                           .addReg(Dest, true, false, false, isDead),
                           Src, isKill, -1);
      break;
    }
    case X86::DEC16r:
    case X86::DEC64_16r:
      if (DisableLEA16) return 0;
      assert(MI->getNumOperands() >= 2 && "Unknown dec instruction!");
      NewMI = addRegOffset(BuildMI(MF, get(X86::LEA16r))
                           .addReg(Dest, true, false, false, isDead),
                           Src, isKill, -1);
      break;
    case X86::ADD64rr:
    case X86::ADD32rr: {
      assert(MI->getNumOperands() >= 3 && "Unknown add instruction!");
      unsigned Opc = MIOpc == X86::ADD64rr ? X86::LEA64r
        : (is64Bit ? X86::LEA64_32r : X86::LEA32r);
      unsigned Src2 = MI->getOperand(2).getReg();
      bool isKill2 = MI->getOperand(2).isKill();
      NewMI = addRegReg(BuildMI(MF, get(Opc))
                        .addReg(Dest, true, false, false, isDead),
                        Src, isKill, Src2, isKill2);
      if (LV && isKill2)
        LV->replaceKillInstruction(Src2, MI, NewMI);
      break;
    }
    case X86::ADD16rr: {
      if (DisableLEA16) return 0;
      assert(MI->getNumOperands() >= 3 && "Unknown add instruction!");
      unsigned Src2 = MI->getOperand(2).getReg();
      bool isKill2 = MI->getOperand(2).isKill();
      NewMI = addRegReg(BuildMI(MF, get(X86::LEA16r))
                        .addReg(Dest, true, false, false, isDead),
                        Src, isKill, Src2, isKill2);
      if (LV && isKill2)
        LV->replaceKillInstruction(Src2, MI, NewMI);
      break;
    }
    case X86::ADD64ri32:
    case X86::ADD64ri8:
      assert(MI->getNumOperands() >= 3 && "Unknown add instruction!");
      if (MI->getOperand(2).isImm())
        NewMI = addRegOffset(BuildMI(MF, get(X86::LEA64r))
                             .addReg(Dest, true, false, false, isDead),
                             Src, isKill, MI->getOperand(2).getImm());
      break;
    case X86::ADD32ri:
    case X86::ADD32ri8:
      assert(MI->getNumOperands() >= 3 && "Unknown add instruction!");
      if (MI->getOperand(2).isImm()) {
        unsigned Opc = is64Bit ? X86::LEA64_32r : X86::LEA32r;
        NewMI = addRegOffset(BuildMI(MF, get(Opc))
                             .addReg(Dest, true, false, false, isDead),
                             Src, isKill, MI->getOperand(2).getImm());
      }
      break;
    case X86::ADD16ri:
    case X86::ADD16ri8:
      if (DisableLEA16) return 0;
      assert(MI->getNumOperands() >= 3 && "Unknown add instruction!");
      if (MI->getOperand(2).isImm())
        NewMI = addRegOffset(BuildMI(MF, get(X86::LEA16r))
                             .addReg(Dest, true, false, false, isDead),
                             Src, isKill, MI->getOperand(2).getImm());
      break;
    case X86::SHL16ri:
      if (DisableLEA16) return 0;
    case X86::SHL32ri:
    case X86::SHL64ri: {
      assert(MI->getNumOperands() >= 3 && MI->getOperand(2).isImm() &&
             "Unknown shl instruction!");
      unsigned ShAmt = MI->getOperand(2).getImm();
      if (ShAmt == 1 || ShAmt == 2 || ShAmt == 3) {
        X86AddressMode AM;
        AM.Scale = 1 << ShAmt;
        AM.IndexReg = Src;
        unsigned Opc = MIOpc == X86::SHL64ri ? X86::LEA64r
          : (MIOpc == X86::SHL32ri
             ? (is64Bit ? X86::LEA64_32r : X86::LEA32r) : X86::LEA16r);
        NewMI = addFullAddress(BuildMI(MF, get(Opc))
                               .addReg(Dest, true, false, false, isDead), AM);
        if (isKill)
          NewMI->getOperand(3).setIsKill(true);
      }
      break;
    }
    }
  }
  }

  if (!NewMI) return 0;

  if (LV) {  // Update live variables
    if (isKill)
      LV->replaceKillInstruction(Src, MI, NewMI);
    if (isDead)
      LV->replaceKillInstruction(Dest, MI, NewMI);
  }

  MFI->insert(MBBI, NewMI);          // Insert the new inst    
  return NewMI;
}

/// commuteInstruction - We have a few instructions that must be hacked on to
/// commute them.
///
MachineInstr *
X86InstrInfo::commuteInstruction(MachineInstr *MI, bool NewMI) const {
  switch (MI->getOpcode()) {
  case X86::SHRD16rri8: // A = SHRD16rri8 B, C, I -> A = SHLD16rri8 C, B, (16-I)
  case X86::SHLD16rri8: // A = SHLD16rri8 B, C, I -> A = SHRD16rri8 C, B, (16-I)
  case X86::SHRD32rri8: // A = SHRD32rri8 B, C, I -> A = SHLD32rri8 C, B, (32-I)
  case X86::SHLD32rri8: // A = SHLD32rri8 B, C, I -> A = SHRD32rri8 C, B, (32-I)
  case X86::SHRD64rri8: // A = SHRD64rri8 B, C, I -> A = SHLD64rri8 C, B, (64-I)
  case X86::SHLD64rri8:{// A = SHLD64rri8 B, C, I -> A = SHRD64rri8 C, B, (64-I)
    unsigned Opc;
    unsigned Size;
    switch (MI->getOpcode()) {
    default: assert(0 && "Unreachable!");
    case X86::SHRD16rri8: Size = 16; Opc = X86::SHLD16rri8; break;
    case X86::SHLD16rri8: Size = 16; Opc = X86::SHRD16rri8; break;
    case X86::SHRD32rri8: Size = 32; Opc = X86::SHLD32rri8; break;
    case X86::SHLD32rri8: Size = 32; Opc = X86::SHRD32rri8; break;
    case X86::SHRD64rri8: Size = 64; Opc = X86::SHLD64rri8; break;
    case X86::SHLD64rri8: Size = 64; Opc = X86::SHRD64rri8; break;
    }
    unsigned Amt = MI->getOperand(3).getImm();
    if (NewMI) {
      MachineFunction &MF = *MI->getParent()->getParent();
      MI = MF.CloneMachineInstr(MI);
      NewMI = false;
    }
    MI->setDesc(get(Opc));
    MI->getOperand(3).setImm(Size-Amt);
    return TargetInstrInfoImpl::commuteInstruction(MI, NewMI);
  }
  case X86::CMOVB16rr:
  case X86::CMOVB32rr:
  case X86::CMOVB64rr:
  case X86::CMOVAE16rr:
  case X86::CMOVAE32rr:
  case X86::CMOVAE64rr:
  case X86::CMOVE16rr:
  case X86::CMOVE32rr:
  case X86::CMOVE64rr:
  case X86::CMOVNE16rr:
  case X86::CMOVNE32rr:
  case X86::CMOVNE64rr:
  case X86::CMOVBE16rr:
  case X86::CMOVBE32rr:
  case X86::CMOVBE64rr:
  case X86::CMOVA16rr:
  case X86::CMOVA32rr:
  case X86::CMOVA64rr:
  case X86::CMOVL16rr:
  case X86::CMOVL32rr:
  case X86::CMOVL64rr:
  case X86::CMOVGE16rr:
  case X86::CMOVGE32rr:
  case X86::CMOVGE64rr:
  case X86::CMOVLE16rr:
  case X86::CMOVLE32rr:
  case X86::CMOVLE64rr:
  case X86::CMOVG16rr:
  case X86::CMOVG32rr:
  case X86::CMOVG64rr:
  case X86::CMOVS16rr:
  case X86::CMOVS32rr:
  case X86::CMOVS64rr:
  case X86::CMOVNS16rr:
  case X86::CMOVNS32rr:
  case X86::CMOVNS64rr:
  case X86::CMOVP16rr:
  case X86::CMOVP32rr:
  case X86::CMOVP64rr:
  case X86::CMOVNP16rr:
  case X86::CMOVNP32rr:
  case X86::CMOVNP64rr:
  case X86::CMOVO16rr:
  case X86::CMOVO32rr:
  case X86::CMOVO64rr:
  case X86::CMOVNO16rr:
  case X86::CMOVNO32rr:
  case X86::CMOVNO64rr: {
    unsigned Opc = 0;
    switch (MI->getOpcode()) {
    default: break;
    case X86::CMOVB16rr:  Opc = X86::CMOVAE16rr; break;
    case X86::CMOVB32rr:  Opc = X86::CMOVAE32rr; break;
    case X86::CMOVB64rr:  Opc = X86::CMOVAE64rr; break;
    case X86::CMOVAE16rr: Opc = X86::CMOVB16rr; break;
    case X86::CMOVAE32rr: Opc = X86::CMOVB32rr; break;
    case X86::CMOVAE64rr: Opc = X86::CMOVB64rr; break;
    case X86::CMOVE16rr:  Opc = X86::CMOVNE16rr; break;
    case X86::CMOVE32rr:  Opc = X86::CMOVNE32rr; break;
    case X86::CMOVE64rr:  Opc = X86::CMOVNE64rr; break;
    case X86::CMOVNE16rr: Opc = X86::CMOVE16rr; break;
    case X86::CMOVNE32rr: Opc = X86::CMOVE32rr; break;
    case X86::CMOVNE64rr: Opc = X86::CMOVE64rr; break;
    case X86::CMOVBE16rr: Opc = X86::CMOVA16rr; break;
    case X86::CMOVBE32rr: Opc = X86::CMOVA32rr; break;
    case X86::CMOVBE64rr: Opc = X86::CMOVA64rr; break;
    case X86::CMOVA16rr:  Opc = X86::CMOVBE16rr; break;
    case X86::CMOVA32rr:  Opc = X86::CMOVBE32rr; break;
    case X86::CMOVA64rr:  Opc = X86::CMOVBE64rr; break;
    case X86::CMOVL16rr:  Opc = X86::CMOVGE16rr; break;
    case X86::CMOVL32rr:  Opc = X86::CMOVGE32rr; break;
    case X86::CMOVL64rr:  Opc = X86::CMOVGE64rr; break;
    case X86::CMOVGE16rr: Opc = X86::CMOVL16rr; break;
    case X86::CMOVGE32rr: Opc = X86::CMOVL32rr; break;
    case X86::CMOVGE64rr: Opc = X86::CMOVL64rr; break;
    case X86::CMOVLE16rr: Opc = X86::CMOVG16rr; break;
    case X86::CMOVLE32rr: Opc = X86::CMOVG32rr; break;
    case X86::CMOVLE64rr: Opc = X86::CMOVG64rr; break;
    case X86::CMOVG16rr:  Opc = X86::CMOVLE16rr; break;
    case X86::CMOVG32rr:  Opc = X86::CMOVLE32rr; break;
    case X86::CMOVG64rr:  Opc = X86::CMOVLE64rr; break;
    case X86::CMOVS16rr:  Opc = X86::CMOVNS16rr; break;
    case X86::CMOVS32rr:  Opc = X86::CMOVNS32rr; break;
    case X86::CMOVS64rr:  Opc = X86::CMOVNS32rr; break;
    case X86::CMOVNS16rr: Opc = X86::CMOVS16rr; break;
    case X86::CMOVNS32rr: Opc = X86::CMOVS32rr; break;
    case X86::CMOVNS64rr: Opc = X86::CMOVS64rr; break;
    case X86::CMOVP16rr:  Opc = X86::CMOVNP16rr; break;
    case X86::CMOVP32rr:  Opc = X86::CMOVNP32rr; break;
    case X86::CMOVP64rr:  Opc = X86::CMOVNP32rr; break;
    case X86::CMOVNP16rr: Opc = X86::CMOVP16rr; break;
    case X86::CMOVNP32rr: Opc = X86::CMOVP32rr; break;
    case X86::CMOVNP64rr: Opc = X86::CMOVP64rr; break;
    case X86::CMOVO16rr:  Opc = X86::CMOVNO16rr; break;
    case X86::CMOVO32rr:  Opc = X86::CMOVNO32rr; break;
    case X86::CMOVO64rr:  Opc = X86::CMOVNO32rr; break;
    case X86::CMOVNO16rr: Opc = X86::CMOVO16rr; break;
    case X86::CMOVNO32rr: Opc = X86::CMOVO32rr; break;
    case X86::CMOVNO64rr: Opc = X86::CMOVO64rr; break;
    }
    if (NewMI) {
      MachineFunction &MF = *MI->getParent()->getParent();
      MI = MF.CloneMachineInstr(MI);
      NewMI = false;
    }
    MI->setDesc(get(Opc));
    // Fallthrough intended.
  }
  default:
    return TargetInstrInfoImpl::commuteInstruction(MI, NewMI);
  }
}

static X86::CondCode GetCondFromBranchOpc(unsigned BrOpc) {
  switch (BrOpc) {
  default: return X86::COND_INVALID;
  case X86::JE:  return X86::COND_E;
  case X86::JNE: return X86::COND_NE;
  case X86::JL:  return X86::COND_L;
  case X86::JLE: return X86::COND_LE;
  case X86::JG:  return X86::COND_G;
  case X86::JGE: return X86::COND_GE;
  case X86::JB:  return X86::COND_B;
  case X86::JBE: return X86::COND_BE;
  case X86::JA:  return X86::COND_A;
  case X86::JAE: return X86::COND_AE;
  case X86::JS:  return X86::COND_S;
  case X86::JNS: return X86::COND_NS;
  case X86::JP:  return X86::COND_P;
  case X86::JNP: return X86::COND_NP;
  case X86::JO:  return X86::COND_O;
  case X86::JNO: return X86::COND_NO;
  }
}

unsigned X86::GetCondBranchFromCond(X86::CondCode CC) {
  switch (CC) {
  default: assert(0 && "Illegal condition code!");
  case X86::COND_E:  return X86::JE;
  case X86::COND_NE: return X86::JNE;
  case X86::COND_L:  return X86::JL;
  case X86::COND_LE: return X86::JLE;
  case X86::COND_G:  return X86::JG;
  case X86::COND_GE: return X86::JGE;
  case X86::COND_B:  return X86::JB;
  case X86::COND_BE: return X86::JBE;
  case X86::COND_A:  return X86::JA;
  case X86::COND_AE: return X86::JAE;
  case X86::COND_S:  return X86::JS;
  case X86::COND_NS: return X86::JNS;
  case X86::COND_P:  return X86::JP;
  case X86::COND_NP: return X86::JNP;
  case X86::COND_O:  return X86::JO;
  case X86::COND_NO: return X86::JNO;
  }
}

/// GetOppositeBranchCondition - Return the inverse of the specified condition,
/// e.g. turning COND_E to COND_NE.
X86::CondCode X86::GetOppositeBranchCondition(X86::CondCode CC) {
  switch (CC) {
  default: assert(0 && "Illegal condition code!");
  case X86::COND_E:  return X86::COND_NE;
  case X86::COND_NE: return X86::COND_E;
  case X86::COND_L:  return X86::COND_GE;
  case X86::COND_LE: return X86::COND_G;
  case X86::COND_G:  return X86::COND_LE;
  case X86::COND_GE: return X86::COND_L;
  case X86::COND_B:  return X86::COND_AE;
  case X86::COND_BE: return X86::COND_A;
  case X86::COND_A:  return X86::COND_BE;
  case X86::COND_AE: return X86::COND_B;
  case X86::COND_S:  return X86::COND_NS;
  case X86::COND_NS: return X86::COND_S;
  case X86::COND_P:  return X86::COND_NP;
  case X86::COND_NP: return X86::COND_P;
  case X86::COND_O:  return X86::COND_NO;
  case X86::COND_NO: return X86::COND_O;
  }
}

bool X86InstrInfo::isUnpredicatedTerminator(const MachineInstr *MI) const {
  const TargetInstrDesc &TID = MI->getDesc();
  if (!TID.isTerminator()) return false;
  
  // Conditional branch is a special case.
  if (TID.isBranch() && !TID.isBarrier())
    return true;
  if (!TID.isPredicable())
    return true;
  return !isPredicated(MI);
}

// For purposes of branch analysis do not count FP_REG_KILL as a terminator.
static bool isBrAnalysisUnpredicatedTerminator(const MachineInstr *MI,
                                               const X86InstrInfo &TII) {
  if (MI->getOpcode() == X86::FP_REG_KILL)
    return false;
  return TII.isUnpredicatedTerminator(MI);
}

bool X86InstrInfo::AnalyzeBranch(MachineBasicBlock &MBB, 
                                 MachineBasicBlock *&TBB,
                                 MachineBasicBlock *&FBB,
                                 SmallVectorImpl<MachineOperand> &Cond) const {
  // Start from the bottom of the block and work up, examining the
  // terminator instructions.
  MachineBasicBlock::iterator I = MBB.end();
  while (I != MBB.begin()) {
    --I;
    // Working from the bottom, when we see a non-terminator
    // instruction, we're done.
    if (!isBrAnalysisUnpredicatedTerminator(I, *this))
      break;
    // A terminator that isn't a branch can't easily be handled
    // by this analysis.
    if (!I->getDesc().isBranch())
      return true;
    // Handle unconditional branches.
    if (I->getOpcode() == X86::JMP) {
      // If the block has any instructions after a JMP, delete them.
      while (next(I) != MBB.end())
        next(I)->eraseFromParent();
      Cond.clear();
      FBB = 0;
      // Delete the JMP if it's equivalent to a fall-through.
      if (MBB.isLayoutSuccessor(I->getOperand(0).getMBB())) {
        TBB = 0;
        I->eraseFromParent();
        I = MBB.end();
        continue;
      }
      // TBB is used to indicate the unconditinal destination.
      TBB = I->getOperand(0).getMBB();
      continue;
    }
    // Handle conditional branches.
    X86::CondCode BranchCode = GetCondFromBranchOpc(I->getOpcode());
    if (BranchCode == X86::COND_INVALID)
      return true;  // Can't handle indirect branch.
    // Working from the bottom, handle the first conditional branch.
    if (Cond.empty()) {
      FBB = TBB;
      TBB = I->getOperand(0).getMBB();
      Cond.push_back(MachineOperand::CreateImm(BranchCode));
      continue;
    }
    // Handle subsequent conditional branches. Only handle the case
    // where all conditional branches branch to the same destination
    // and their condition opcodes fit one of the special
    // multi-branch idioms.
    assert(Cond.size() == 1);
    assert(TBB);
    // Only handle the case where all conditional branches branch to
    // the same destination.
    if (TBB != I->getOperand(0).getMBB())
      return true;
    X86::CondCode OldBranchCode = (X86::CondCode)Cond[0].getImm();
    // If the conditions are the same, we can leave them alone.
    if (OldBranchCode == BranchCode)
      continue;
    // If they differ, see if they fit one of the known patterns.
    // Theoretically we could handle more patterns here, but
    // we shouldn't expect to see them if instruction selection
    // has done a reasonable job.
    if ((OldBranchCode == X86::COND_NP &&
         BranchCode == X86::COND_E) ||
        (OldBranchCode == X86::COND_E &&
         BranchCode == X86::COND_NP))
      BranchCode = X86::COND_NP_OR_E;
    else if ((OldBranchCode == X86::COND_P &&
              BranchCode == X86::COND_NE) ||
             (OldBranchCode == X86::COND_NE &&
              BranchCode == X86::COND_P))
      BranchCode = X86::COND_NE_OR_P;
    else
      return true;
    // Update the MachineOperand.
    Cond[0].setImm(BranchCode);
  }

  return false;
}

unsigned X86InstrInfo::RemoveBranch(MachineBasicBlock &MBB) const {
  MachineBasicBlock::iterator I = MBB.end();
  unsigned Count = 0;

  while (I != MBB.begin()) {
    --I;
    if (I->getOpcode() != X86::JMP &&
        GetCondFromBranchOpc(I->getOpcode()) == X86::COND_INVALID)
      break;
    // Remove the branch.
    I->eraseFromParent();
    I = MBB.end();
    ++Count;
  }
  
  return Count;
}

static const MachineInstrBuilder &X86InstrAddOperand(MachineInstrBuilder &MIB,
                                                     const MachineOperand &MO) {
  if (MO.isReg())
    MIB = MIB.addReg(MO.getReg(), MO.isDef(), MO.isImplicit(),
                     MO.isKill(), MO.isDead(), MO.getSubReg());
  else if (MO.isImm())
    MIB = MIB.addImm(MO.getImm());
  else if (MO.isFI())
    MIB = MIB.addFrameIndex(MO.getIndex());
  else if (MO.isGlobal())
    MIB = MIB.addGlobalAddress(MO.getGlobal(), MO.getOffset());
  else if (MO.isCPI())
    MIB = MIB.addConstantPoolIndex(MO.getIndex(), MO.getOffset());
  else if (MO.isJTI())
    MIB = MIB.addJumpTableIndex(MO.getIndex());
  else if (MO.isSymbol())
    MIB = MIB.addExternalSymbol(MO.getSymbolName());
  else
    assert(0 && "Unknown operand for X86InstrAddOperand!");

  return MIB;
}

unsigned
X86InstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
                           MachineBasicBlock *FBB,
                           const SmallVectorImpl<MachineOperand> &Cond) const {
  // Shouldn't be a fall through.
  assert(TBB && "InsertBranch must not be told to insert a fallthrough");
  assert((Cond.size() == 1 || Cond.size() == 0) &&
         "X86 branch conditions have one component!");

  if (Cond.empty()) {
    // Unconditional branch?
    assert(!FBB && "Unconditional branch with multiple successors!");
    BuildMI(&MBB, get(X86::JMP)).addMBB(TBB);
    return 1;
  }

  // Conditional branch.
  unsigned Count = 0;
  X86::CondCode CC = (X86::CondCode)Cond[0].getImm();
  switch (CC) {
  case X86::COND_NP_OR_E:
    // Synthesize NP_OR_E with two branches.
    BuildMI(&MBB, get(X86::JNP)).addMBB(TBB);
    ++Count;
    BuildMI(&MBB, get(X86::JE)).addMBB(TBB);
    ++Count;
    break;
  case X86::COND_NE_OR_P:
    // Synthesize NE_OR_P with two branches.
    BuildMI(&MBB, get(X86::JNE)).addMBB(TBB);
    ++Count;
    BuildMI(&MBB, get(X86::JP)).addMBB(TBB);
    ++Count;
    break;
  default: {
    unsigned Opc = GetCondBranchFromCond(CC);
    BuildMI(&MBB, get(Opc)).addMBB(TBB);
    ++Count;
  }
  }
  if (FBB) {
    // Two-way Conditional branch. Insert the second branch.
    BuildMI(&MBB, get(X86::JMP)).addMBB(FBB);
    ++Count;
  }
  return Count;
}

bool X86InstrInfo::copyRegToReg(MachineBasicBlock &MBB,
                                MachineBasicBlock::iterator MI,
                                unsigned DestReg, unsigned SrcReg,
                                const TargetRegisterClass *DestRC,
                                const TargetRegisterClass *SrcRC) const {
  if (DestRC == SrcRC) {
    unsigned Opc;
    if (DestRC == &X86::GR64RegClass) {
      Opc = X86::MOV64rr;
    } else if (DestRC == &X86::GR32RegClass) {
      Opc = X86::MOV32rr;
    } else if (DestRC == &X86::GR16RegClass) {
      Opc = X86::MOV16rr;
    } else if (DestRC == &X86::GR8RegClass) {
      Opc = X86::MOV8rr;
    } else if (DestRC == &X86::GR32_RegClass) {
      Opc = X86::MOV32_rr;
    } else if (DestRC == &X86::GR16_RegClass) {
      Opc = X86::MOV16_rr;
    } else if (DestRC == &X86::RFP32RegClass) {
      Opc = X86::MOV_Fp3232;
    } else if (DestRC == &X86::RFP64RegClass || DestRC == &X86::RSTRegClass) {
      Opc = X86::MOV_Fp6464;
    } else if (DestRC == &X86::RFP80RegClass) {
      Opc = X86::MOV_Fp8080;
    } else if (DestRC == &X86::FR32RegClass) {
      Opc = X86::FsMOVAPSrr;
    } else if (DestRC == &X86::FR64RegClass) {
      Opc = X86::FsMOVAPDrr;
    } else if (DestRC == &X86::VR128RegClass) {
      Opc = X86::MOVAPSrr;
    } else if (DestRC == &X86::VR64RegClass) {
      Opc = X86::MMX_MOVQ64rr;
    } else {
      return false;
    }
    BuildMI(MBB, MI, get(Opc), DestReg).addReg(SrcReg);
    return true;
  }
  
  // Moving EFLAGS to / from another register requires a push and a pop.
  if (SrcRC == &X86::CCRRegClass) {
    if (SrcReg != X86::EFLAGS)
      return false;
    if (DestRC == &X86::GR64RegClass) {
      BuildMI(MBB, MI, get(X86::PUSHFQ));
      BuildMI(MBB, MI, get(X86::POP64r), DestReg);
      return true;
    } else if (DestRC == &X86::GR32RegClass) {
      BuildMI(MBB, MI, get(X86::PUSHFD));
      BuildMI(MBB, MI, get(X86::POP32r), DestReg);
      return true;
    }
  } else if (DestRC == &X86::CCRRegClass) {
    if (DestReg != X86::EFLAGS)
      return false;
    if (SrcRC == &X86::GR64RegClass) {
      BuildMI(MBB, MI, get(X86::PUSH64r)).addReg(SrcReg);
      BuildMI(MBB, MI, get(X86::POPFQ));
      return true;
    } else if (SrcRC == &X86::GR32RegClass) {
      BuildMI(MBB, MI, get(X86::PUSH32r)).addReg(SrcReg);
      BuildMI(MBB, MI, get(X86::POPFD));
      return true;
    }
  }
  
  // Moving from ST(0) turns into FpGET_ST0_32 etc.
  if (SrcRC == &X86::RSTRegClass) {
    // Copying from ST(0)/ST(1).
    if (SrcReg != X86::ST0 && SrcReg != X86::ST1)
      // Can only copy from ST(0)/ST(1) right now
      return false;
    bool isST0 = SrcReg == X86::ST0;
    unsigned Opc;
    if (DestRC == &X86::RFP32RegClass)
      Opc = isST0 ? X86::FpGET_ST0_32 : X86::FpGET_ST1_32;
    else if (DestRC == &X86::RFP64RegClass)
      Opc = isST0 ? X86::FpGET_ST0_64 : X86::FpGET_ST1_64;
    else {
      if (DestRC != &X86::RFP80RegClass)
        return false;
      Opc = isST0 ? X86::FpGET_ST0_80 : X86::FpGET_ST1_80;
    }
    BuildMI(MBB, MI, get(Opc), DestReg);
    return true;
  }

  // Moving to ST(0) turns into FpSET_ST0_32 etc.
  if (DestRC == &X86::RSTRegClass) {
    // Copying to ST(0).  FIXME: handle ST(1) also
    if (DestReg != X86::ST0)
      // Can only copy to TOS right now
      return false;
    unsigned Opc;
    if (SrcRC == &X86::RFP32RegClass)
      Opc = X86::FpSET_ST0_32;
    else if (SrcRC == &X86::RFP64RegClass)
      Opc = X86::FpSET_ST0_64;
    else {
      if (SrcRC != &X86::RFP80RegClass)
        return false;
      Opc = X86::FpSET_ST0_80;
    }
    BuildMI(MBB, MI, get(Opc)).addReg(SrcReg);
    return true;
  }
  
  // Not yet supported!
  return false;
}

static unsigned getStoreRegOpcode(const TargetRegisterClass *RC,
                                  bool isStackAligned) {
  unsigned Opc = 0;
  if (RC == &X86::GR64RegClass) {
    Opc = X86::MOV64mr;
  } else if (RC == &X86::GR32RegClass) {
    Opc = X86::MOV32mr;
  } else if (RC == &X86::GR16RegClass) {
    Opc = X86::MOV16mr;
  } else if (RC == &X86::GR8RegClass) {
    Opc = X86::MOV8mr;
  } else if (RC == &X86::GR32_RegClass) {
    Opc = X86::MOV32_mr;
  } else if (RC == &X86::GR16_RegClass) {
    Opc = X86::MOV16_mr;
  } else if (RC == &X86::RFP80RegClass) {
    Opc = X86::ST_FpP80m;   // pops
  } else if (RC == &X86::RFP64RegClass) {
    Opc = X86::ST_Fp64m;
  } else if (RC == &X86::RFP32RegClass) {
    Opc = X86::ST_Fp32m;
  } else if (RC == &X86::FR32RegClass) {
    Opc = X86::MOVSSmr;
  } else if (RC == &X86::FR64RegClass) {
    Opc = X86::MOVSDmr;
  } else if (RC == &X86::VR128RegClass) {
    // If stack is realigned we can use aligned stores.
    Opc = isStackAligned ? X86::MOVAPSmr : X86::MOVUPSmr;
  } else if (RC == &X86::VR64RegClass) {
    Opc = X86::MMX_MOVQ64mr;
  } else {
    assert(0 && "Unknown regclass");
    abort();
  }

  return Opc;
}

void X86InstrInfo::storeRegToStackSlot(MachineBasicBlock &MBB,
                                       MachineBasicBlock::iterator MI,
                                       unsigned SrcReg, bool isKill, int FrameIdx,
                                       const TargetRegisterClass *RC) const {
  const MachineFunction &MF = *MBB.getParent();
  bool isAligned = (RI.getStackAlignment() >= 16) ||
    RI.needsStackRealignment(MF);
  unsigned Opc = getStoreRegOpcode(RC, isAligned);
  addFrameReference(BuildMI(MBB, MI, get(Opc)), FrameIdx)
    .addReg(SrcReg, false, false, isKill);
}

void X86InstrInfo::storeRegToAddr(MachineFunction &MF, unsigned SrcReg,
                                  bool isKill,
                                  SmallVectorImpl<MachineOperand> &Addr,
                                  const TargetRegisterClass *RC,
                                  SmallVectorImpl<MachineInstr*> &NewMIs) const {
  bool isAligned = (RI.getStackAlignment() >= 16) ||
    RI.needsStackRealignment(MF);
  unsigned Opc = getStoreRegOpcode(RC, isAligned);
  MachineInstrBuilder MIB = BuildMI(MF, get(Opc));
  for (unsigned i = 0, e = Addr.size(); i != e; ++i)
    MIB = X86InstrAddOperand(MIB, Addr[i]);
  MIB.addReg(SrcReg, false, false, isKill);
  NewMIs.push_back(MIB);
}

static unsigned getLoadRegOpcode(const TargetRegisterClass *RC,
                                 bool isStackAligned) {
  unsigned Opc = 0;
  if (RC == &X86::GR64RegClass) {
    Opc = X86::MOV64rm;
  } else if (RC == &X86::GR32RegClass) {
    Opc = X86::MOV32rm;
  } else if (RC == &X86::GR16RegClass) {
    Opc = X86::MOV16rm;
  } else if (RC == &X86::GR8RegClass) {
    Opc = X86::MOV8rm;
  } else if (RC == &X86::GR32_RegClass) {
    Opc = X86::MOV32_rm;
  } else if (RC == &X86::GR16_RegClass) {
    Opc = X86::MOV16_rm;
  } else if (RC == &X86::RFP80RegClass) {
    Opc = X86::LD_Fp80m;
  } else if (RC == &X86::RFP64RegClass) {
    Opc = X86::LD_Fp64m;
  } else if (RC == &X86::RFP32RegClass) {
    Opc = X86::LD_Fp32m;
  } else if (RC == &X86::FR32RegClass) {
    Opc = X86::MOVSSrm;
  } else if (RC == &X86::FR64RegClass) {
    Opc = X86::MOVSDrm;
  } else if (RC == &X86::VR128RegClass) {
    // If stack is realigned we can use aligned loads.
    Opc = isStackAligned ? X86::MOVAPSrm : X86::MOVUPSrm;
  } else if (RC == &X86::VR64RegClass) {
    Opc = X86::MMX_MOVQ64rm;
  } else {
    assert(0 && "Unknown regclass");
    abort();
  }

  return Opc;
}

void X86InstrInfo::loadRegFromStackSlot(MachineBasicBlock &MBB,
                                        MachineBasicBlock::iterator MI,
                                        unsigned DestReg, int FrameIdx,
                                        const TargetRegisterClass *RC) const{
  const MachineFunction &MF = *MBB.getParent();
  bool isAligned = (RI.getStackAlignment() >= 16) ||
    RI.needsStackRealignment(MF);
  unsigned Opc = getLoadRegOpcode(RC, isAligned);
  addFrameReference(BuildMI(MBB, MI, get(Opc), DestReg), FrameIdx);
}

void X86InstrInfo::loadRegFromAddr(MachineFunction &MF, unsigned DestReg,
                                 SmallVectorImpl<MachineOperand> &Addr,
                                 const TargetRegisterClass *RC,
                                 SmallVectorImpl<MachineInstr*> &NewMIs) const {
  bool isAligned = (RI.getStackAlignment() >= 16) ||
    RI.needsStackRealignment(MF);
  unsigned Opc = getLoadRegOpcode(RC, isAligned);
  MachineInstrBuilder MIB = BuildMI(MF, get(Opc), DestReg);
  for (unsigned i = 0, e = Addr.size(); i != e; ++i)
    MIB = X86InstrAddOperand(MIB, Addr[i]);
  NewMIs.push_back(MIB);
}

bool X86InstrInfo::spillCalleeSavedRegisters(MachineBasicBlock &MBB,
                                                MachineBasicBlock::iterator MI,
                                const std::vector<CalleeSavedInfo> &CSI) const {
  if (CSI.empty())
    return false;

  bool is64Bit = TM.getSubtarget<X86Subtarget>().is64Bit();
  unsigned SlotSize = is64Bit ? 8 : 4;

  MachineFunction &MF = *MBB.getParent();
  X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
  X86FI->setCalleeSavedFrameSize(CSI.size() * SlotSize);
  
  unsigned Opc = is64Bit ? X86::PUSH64r : X86::PUSH32r;
  for (unsigned i = CSI.size(); i != 0; --i) {
    unsigned Reg = CSI[i-1].getReg();
    // Add the callee-saved register as live-in. It's killed at the spill.
    MBB.addLiveIn(Reg);
    BuildMI(MBB, MI, get(Opc))
      .addReg(Reg, /*isDef=*/false, /*isImp=*/false, /*isKill=*/true);
  }
  return true;
}

bool X86InstrInfo::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
                                                 MachineBasicBlock::iterator MI,
                                const std::vector<CalleeSavedInfo> &CSI) const {
  if (CSI.empty())
    return false;
    
  bool is64Bit = TM.getSubtarget<X86Subtarget>().is64Bit();

  unsigned Opc = is64Bit ? X86::POP64r : X86::POP32r;
  for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
    unsigned Reg = CSI[i].getReg();
    BuildMI(MBB, MI, get(Opc), Reg);
  }
  return true;
}

static MachineInstr *FuseTwoAddrInst(MachineFunction &MF, unsigned Opcode,
                                     const SmallVectorImpl<MachineOperand> &MOs,
                                     MachineInstr *MI,
                                     const TargetInstrInfo &TII) {
  // Create the base instruction with the memory operand as the first part.
  MachineInstr *NewMI = MF.CreateMachineInstr(TII.get(Opcode),
                                              MI->getDebugLoc(), true);
  MachineInstrBuilder MIB(NewMI);
  unsigned NumAddrOps = MOs.size();
  for (unsigned i = 0; i != NumAddrOps; ++i)
    MIB = X86InstrAddOperand(MIB, MOs[i]);
  if (NumAddrOps < 4)  // FrameIndex only
    MIB.addImm(1).addReg(0).addImm(0);
  
  // Loop over the rest of the ri operands, converting them over.
  unsigned NumOps = MI->getDesc().getNumOperands()-2;
  for (unsigned i = 0; i != NumOps; ++i) {
    MachineOperand &MO = MI->getOperand(i+2);
    MIB = X86InstrAddOperand(MIB, MO);
  }
  for (unsigned i = NumOps+2, e = MI->getNumOperands(); i != e; ++i) {
    MachineOperand &MO = MI->getOperand(i);
    MIB = X86InstrAddOperand(MIB, MO);
  }
  return MIB;
}

static MachineInstr *FuseInst(MachineFunction &MF,
                              unsigned Opcode, unsigned OpNo,
                              const SmallVectorImpl<MachineOperand> &MOs,
                              MachineInstr *MI, const TargetInstrInfo &TII) {
  MachineInstr *NewMI = MF.CreateMachineInstr(TII.get(Opcode),
                                              MI->getDebugLoc(), true);
  MachineInstrBuilder MIB(NewMI);
  
  for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
    MachineOperand &MO = MI->getOperand(i);
    if (i == OpNo) {
      assert(MO.isReg() && "Expected to fold into reg operand!");
      unsigned NumAddrOps = MOs.size();
      for (unsigned i = 0; i != NumAddrOps; ++i)
        MIB = X86InstrAddOperand(MIB, MOs[i]);
      if (NumAddrOps < 4)  // FrameIndex only
        MIB.addImm(1).addReg(0).addImm(0);
    } else {
      MIB = X86InstrAddOperand(MIB, MO);
    }
  }
  return MIB;
}

static MachineInstr *MakeM0Inst(const TargetInstrInfo &TII, unsigned Opcode,
                                const SmallVectorImpl<MachineOperand> &MOs,
                                MachineInstr *MI) {
  MachineFunction &MF = *MI->getParent()->getParent();
  MachineInstrBuilder MIB = BuildMI(MF, TII.get(Opcode));

  unsigned NumAddrOps = MOs.size();
  for (unsigned i = 0; i != NumAddrOps; ++i)
    MIB = X86InstrAddOperand(MIB, MOs[i]);
  if (NumAddrOps < 4)  // FrameIndex only
    MIB.addImm(1).addReg(0).addImm(0);