Target/Hexagon/HexagonAsmPrinter.cpp

//===-- HexagonAsmPrinter.cpp - Print machine instrs to Hexagon assembly --===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains a printer that converts from our internal representation
// of machine-dependent LLVM code to Hexagon assembly language. This printer is
// the output mechanism used by `llc'.
//
//===----------------------------------------------------------------------===//

#include "Hexagon.h"
#include "HexagonAsmPrinter.h"
#include "HexagonMachineFunctionInfo.h"
#include "HexagonSubtarget.h"
#include "HexagonTargetMachine.h"
#include "MCTargetDesc/HexagonInstPrinter.h"
#include "MCTargetDesc/HexagonMCInstrInfo.h"
#include "MCTargetDesc/HexagonMCShuffler.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ELF.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Target/TargetRegisterInfo.h"

using namespace llvm;

namespace llvm {
  void HexagonLowerToMC(const MCInstrInfo &MCII, const MachineInstr *MI,
                        MCInst &MCB, HexagonAsmPrinter &AP);
}

#define DEBUG_TYPE "asm-printer"

static cl::opt<bool> AlignCalls(
         "hexagon-align-calls", cl::Hidden, cl::init(true),
          cl::desc("Insert falign after call instruction for Hexagon target"));

// Given a scalar register return its pair.
inline static unsigned getHexagonRegisterPair(unsigned Reg,
      const MCRegisterInfo *RI) {
  assert(Hexagon::IntRegsRegClass.contains(Reg));
  MCSuperRegIterator SR(Reg, RI, false);
  unsigned Pair = *SR;
  assert(Hexagon::DoubleRegsRegClass.contains(Pair));
  return Pair;
}

HexagonAsmPrinter::HexagonAsmPrinter(TargetMachine &TM,
                                     std::unique_ptr<MCStreamer> Streamer)
    : AsmPrinter(TM, std::move(Streamer)), Subtarget(nullptr) {}

void HexagonAsmPrinter::printOperand(const MachineInstr *MI, unsigned OpNo,
                                    raw_ostream &O) {
  const MachineOperand &MO = MI->getOperand(OpNo);

  switch (MO.getType()) {
  default: llvm_unreachable ("<unknown operand type>");
  case MachineOperand::MO_Register:
    O << HexagonInstPrinter::getRegisterName(MO.getReg());
    return;
  case MachineOperand::MO_Immediate:
    O << MO.getImm();
    return;
  case MachineOperand::MO_MachineBasicBlock:
    MO.getMBB()->getSymbol()->print(O, MAI);
    return;
  case MachineOperand::MO_ConstantPoolIndex:
    GetCPISymbol(MO.getIndex())->print(O, MAI);
    return;
  case MachineOperand::MO_GlobalAddress:
    // Computing the address of a global symbol, not calling it.
    getSymbol(MO.getGlobal())->print(O, MAI);
    printOffset(MO.getOffset(), O);
    return;
  }
}

//
// isBlockOnlyReachableByFallthrough - We need to override this since the
// default AsmPrinter does not print labels for any basic block that
// is only reachable by a fall through. That works for all cases except
// for the case in which the basic block is reachable by a fall through but
// through an indirect from a jump table. In this case, the jump table
// will contain a label not defined by AsmPrinter.
//
bool HexagonAsmPrinter::
isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const {
  if (MBB->hasAddressTaken())
    return false;
  return AsmPrinter::isBlockOnlyReachableByFallthrough(MBB);
}


/// PrintAsmOperand - Print out an operand for an inline asm expression.
///
bool HexagonAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
                                        unsigned AsmVariant,
                                        const char *ExtraCode,
                                        raw_ostream &OS) {
  // Does this asm operand have a single letter operand modifier?
  if (ExtraCode && ExtraCode[0]) {
    if (ExtraCode[1] != 0)
      return true; // Unknown modifier.

    switch (ExtraCode[0]) {
    default:
      // See if this is a generic print operand
      return AsmPrinter::PrintAsmOperand(MI, OpNo, AsmVariant, ExtraCode, OS);
    case 'c': // Don't print "$" before a global var name or constant.
      // Hexagon never has a prefix.
      printOperand(MI, OpNo, OS);
      return false;
    case 'L': // Write second word of DImode reference.
      // Verify that this operand has two consecutive registers.
      if (!MI->getOperand(OpNo).isReg() ||
          OpNo+1 == MI->getNumOperands() ||
          !MI->getOperand(OpNo+1).isReg())
        return true;
      ++OpNo;   // Return the high-part.
      break;
    case 'I':
      // Write 'i' if an integer constant, otherwise nothing.  Used to print
      // addi vs add, etc.
      if (MI->getOperand(OpNo).isImm())
        OS << "i";
      return false;
    }
  }

  printOperand(MI, OpNo, OS);
  return false;
}

bool HexagonAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
                                            unsigned OpNo, unsigned AsmVariant,
                                            const char *ExtraCode,
                                            raw_ostream &O) {
  if (ExtraCode && ExtraCode[0])
    return true; // Unknown modifier.

  const MachineOperand &Base  = MI->getOperand(OpNo);
  const MachineOperand &Offset = MI->getOperand(OpNo+1);

  if (Base.isReg())
    printOperand(MI, OpNo, O);
  else
    llvm_unreachable("Unimplemented");

  if (Offset.isImm()) {
    if (Offset.getImm())
      O << " + #" << Offset.getImm();
  }
  else
    llvm_unreachable("Unimplemented");

  return false;
}

static MCSymbol *smallData(AsmPrinter &AP, const MachineInstr &MI,
                           MCStreamer &OutStreamer, const MCOperand &Imm,
                           int AlignSize) {
  MCSymbol *Sym;
  int64_t Value;
  if (Imm.getExpr()->evaluateAsAbsolute(Value)) {
    StringRef sectionPrefix;
    std::string ImmString;
    StringRef Name;
    if (AlignSize == 8) {
       Name = ".CONST_0000000000000000";
       sectionPrefix = ".gnu.linkonce.l8";
       ImmString = utohexstr(Value);
    } else {
       Name = ".CONST_00000000";
       sectionPrefix = ".gnu.linkonce.l4";
       ImmString = utohexstr(static_cast<uint32_t>(Value));
    }

    std::string symbolName =   // Yes, leading zeros are kept.
      Name.drop_back(ImmString.size()).str() + ImmString;
    std::string sectionName = sectionPrefix.str() + symbolName;

    MCSectionELF *Section = OutStreamer.getContext().getELFSection(
        sectionName, ELF::SHT_PROGBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC);
    OutStreamer.SwitchSection(Section);

    Sym = AP.OutContext.getOrCreateSymbol(Twine(symbolName));
    if (Sym->isUndefined()) {
      OutStreamer.EmitLabel(Sym);
      OutStreamer.EmitSymbolAttribute(Sym, MCSA_Global);
      OutStreamer.EmitIntValue(Value, AlignSize);
      OutStreamer.EmitCodeAlignment(AlignSize);
    }
  } else {
    assert(Imm.isExpr() && "Expected expression and found none");
    const MachineOperand &MO = MI.getOperand(1);
    assert(MO.isGlobal() || MO.isCPI() || MO.isJTI());
    MCSymbol *MOSymbol = nullptr;
    if (MO.isGlobal())
      MOSymbol = AP.getSymbol(MO.getGlobal());
    else if (MO.isCPI())
      MOSymbol = AP.GetCPISymbol(MO.getIndex());
    else if (MO.isJTI())
      MOSymbol = AP.GetJTISymbol(MO.getIndex());
    else
      llvm_unreachable("Unknown operand type!");

    StringRef SymbolName = MOSymbol->getName();
    std::string LitaName = ".CONST_" + SymbolName.str();

    MCSectionELF *Section = OutStreamer.getContext().getELFSection(
        ".lita", ELF::SHT_PROGBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC);

    OutStreamer.SwitchSection(Section);
    Sym = AP.OutContext.getOrCreateSymbol(Twine(LitaName));
    if (Sym->isUndefined()) {
      OutStreamer.EmitLabel(Sym);
      OutStreamer.EmitSymbolAttribute(Sym, MCSA_Local);
      OutStreamer.EmitValue(Imm.getExpr(), AlignSize);
      OutStreamer.EmitCodeAlignment(AlignSize);
    }
  }
  return Sym;
}

void HexagonAsmPrinter::HexagonProcessInstruction(MCInst &Inst,
                                                  const MachineInstr &MI) {
  MCInst &MappedInst = static_cast <MCInst &>(Inst);
  const MCRegisterInfo *RI = OutStreamer->getContext().getRegisterInfo();

  switch (Inst.getOpcode()) {
  default: return;

  case Hexagon::A2_iconst: {
    Inst.setOpcode(Hexagon::A2_addi);
    MCOperand Reg = Inst.getOperand(0);
    MCOperand S16 = Inst.getOperand(1);
    HexagonMCInstrInfo::setMustNotExtend(*S16.getExpr());
    HexagonMCInstrInfo::setS23_2_reloc(*S16.getExpr());
    Inst.clear();
    Inst.addOperand(Reg);
    Inst.addOperand(MCOperand::createReg(Hexagon::R0));
    Inst.addOperand(S16);
    break;
  }

  // "$dst = CONST64(#$src1)",
  case Hexagon::CONST64_Float_Real:
  case Hexagon::CONST64_Int_Real:
    if (!OutStreamer->hasRawTextSupport()) {
      const MCOperand &Imm = MappedInst.getOperand(1);
      MCSectionSubPair Current = OutStreamer->getCurrentSection();

      MCSymbol *Sym = smallData(*this, MI, *OutStreamer, Imm, 8);

      OutStreamer->SwitchSection(Current.first, Current.second);
      MCInst TmpInst;
      MCOperand &Reg = MappedInst.getOperand(0);
      TmpInst.setOpcode(Hexagon::L2_loadrdgp);
      TmpInst.addOperand(Reg);
      TmpInst.addOperand(MCOperand::createExpr(
                         MCSymbolRefExpr::create(Sym, OutContext)));
      MappedInst = TmpInst;

    }
    break;
  case Hexagon::CONST32:
  case Hexagon::CONST32_Float_Real:
  case Hexagon::CONST32_Int_Real:
  case Hexagon::FCONST32_nsdata:
    if (!OutStreamer->hasRawTextSupport()) {
      MCOperand &Imm = MappedInst.getOperand(1);
      MCSectionSubPair Current = OutStreamer->getCurrentSection();
      MCSymbol *Sym = smallData(*this, MI, *OutStreamer, Imm, 4);
      OutStreamer->SwitchSection(Current.first, Current.second);
      MCInst TmpInst;
      MCOperand &Reg = MappedInst.getOperand(0);
      TmpInst.setOpcode(Hexagon::L2_loadrigp);
      TmpInst.addOperand(Reg);
      TmpInst.addOperand(MCOperand::createExpr(HexagonMCExpr::create(
          MCSymbolRefExpr::create(Sym, OutContext), OutContext)));
      MappedInst = TmpInst;
    }
    break;

  // C2_pxfer_map maps to C2_or instruction. Though, it's possible to use
  // C2_or during instruction selection itself but it results
  // into suboptimal code.
  case Hexagon::C2_pxfer_map: {
    MCOperand &Ps = Inst.getOperand(1);
    MappedInst.setOpcode(Hexagon::C2_or);
    MappedInst.addOperand(Ps);
    return;
  }

  // Vector reduce complex multiply by scalar, Rt & 1 map to :hi else :lo
  // The insn is mapped from the 4 operand to the 3 operand raw form taking
  // 3 register pairs.
  case Hexagon::M2_vrcmpys_acc_s1: {
    MCOperand &Rt = Inst.getOperand(3);
    assert (Rt.isReg() && "Expected register and none was found");
    unsigned Reg = RI->getEncodingValue(Rt.getReg());
    if (Reg & 1)
      MappedInst.setOpcode(Hexagon::M2_vrcmpys_acc_s1_h);
    else
      MappedInst.setOpcode(Hexagon::M2_vrcmpys_acc_s1_l);
    Rt.setReg(getHexagonRegisterPair(Rt.getReg(), RI));
    return;
  }
  case Hexagon::M2_vrcmpys_s1: {
    MCOperand &Rt = Inst.getOperand(2);
    assert (Rt.isReg() && "Expected register and none was found");
    unsigned Reg = RI->getEncodingValue(Rt.getReg());
    if (Reg & 1)
      MappedInst.setOpcode(Hexagon::M2_vrcmpys_s1_h);
    else
      MappedInst.setOpcode(Hexagon::M2_vrcmpys_s1_l);
    Rt.setReg(getHexagonRegisterPair(Rt.getReg(), RI));
    return;
  }

  case Hexagon::M2_vrcmpys_s1rp: {
    MCOperand &Rt = Inst.getOperand(2);
    assert (Rt.isReg() && "Expected register and none was found");
    unsigned Reg = RI->getEncodingValue(Rt.getReg());
    if (Reg & 1)
      MappedInst.setOpcode(Hexagon::M2_vrcmpys_s1rp_h);
    else
      MappedInst.setOpcode(Hexagon::M2_vrcmpys_s1rp_l);
    Rt.setReg(getHexagonRegisterPair(Rt.getReg(), RI));
    return;
  }

  case Hexagon::A4_boundscheck: {
    MCOperand &Rs = Inst.getOperand(1);
    assert (Rs.isReg() && "Expected register and none was found");
    unsigned Reg = RI->getEncodingValue(Rs.getReg());
    if (Reg & 1) // Odd mapped to raw:hi, regpair is rodd:odd-1, like r3:2
      MappedInst.setOpcode(Hexagon::A4_boundscheck_hi);
    else         // raw:lo
      MappedInst.setOpcode(Hexagon::A4_boundscheck_lo);
    Rs.setReg(getHexagonRegisterPair(Rs.getReg(), RI));
    return;
  }
  case Hexagon::S5_asrhub_rnd_sat_goodsyntax: {
    MCOperand &MO = MappedInst.getOperand(2);
    int64_t Imm;
    MCExpr const *Expr = MO.getExpr();
    bool Success = Expr->evaluateAsAbsolute(Imm);
    assert (Success && "Expected immediate and none was found");
    (void)Success;
    MCInst TmpInst;
    if (Imm == 0) {
      TmpInst.setOpcode(Hexagon::S2_vsathub);
      TmpInst.addOperand(MappedInst.getOperand(0));
      TmpInst.addOperand(MappedInst.getOperand(1));
      MappedInst = TmpInst;
      return;
    }
    TmpInst.setOpcode(Hexagon::S5_asrhub_rnd_sat);
    TmpInst.addOperand(MappedInst.getOperand(0));
    TmpInst.addOperand(MappedInst.getOperand(1));
    const MCExpr *One = MCConstantExpr::create(1, OutContext);
    const MCExpr *Sub = MCBinaryExpr::createSub(Expr, One, OutContext);
    TmpInst.addOperand(
        MCOperand::createExpr(HexagonMCExpr::create(Sub, OutContext)));
    MappedInst = TmpInst;
    return;
  }
  case Hexagon::S5_vasrhrnd_goodsyntax:
  case Hexagon::S2_asr_i_p_rnd_goodsyntax: {
    MCOperand &MO2 = MappedInst.getOperand(2);
    MCExpr const *Expr = MO2.getExpr();
    int64_t Imm;
    bool Success = Expr->evaluateAsAbsolute(Imm);
    assert (Success && "Expected immediate and none was found");
    (void)Success;
    MCInst TmpInst;
    if (Imm == 0) {
      TmpInst.setOpcode(Hexagon::A2_combinew);
      TmpInst.addOperand(MappedInst.getOperand(0));
      MCOperand &MO1 = MappedInst.getOperand(1);
      unsigned High = RI->getSubReg(MO1.getReg(), Hexagon::subreg_hireg);
      unsigned Low = RI->getSubReg(MO1.getReg(), Hexagon::subreg_loreg);
      // Add a new operand for the second register in the pair.
      TmpInst.addOperand(MCOperand::createReg(High));
      TmpInst.addOperand(MCOperand::createReg(Low));
      MappedInst = TmpInst;
      return;
    }

    if (Inst.getOpcode() == Hexagon::S2_asr_i_p_rnd_goodsyntax)
      TmpInst.setOpcode(Hexagon::S2_asr_i_p_rnd);
    else
      TmpInst.setOpcode(Hexagon::S5_vasrhrnd);
    TmpInst.addOperand(MappedInst.getOperand(0));
    TmpInst.addOperand(MappedInst.getOperand(1));
    const MCExpr *One = MCConstantExpr::create(1, OutContext);
    const MCExpr *Sub = MCBinaryExpr::createSub(Expr, One, OutContext);
    TmpInst.addOperand(
        MCOperand::createExpr(HexagonMCExpr::create(Sub, OutContext)));
    MappedInst = TmpInst;
    return;
  }
  // if ("#u5==0") Assembler mapped to: "Rd=Rs"; else Rd=asr(Rs,#u5-1):rnd
  case Hexagon::S2_asr_i_r_rnd_goodsyntax: {
    MCOperand &MO = Inst.getOperand(2);
    MCExpr const *Expr = MO.getExpr();
    int64_t Imm;
    bool Success = Expr->evaluateAsAbsolute(Imm);
    assert (Success && "Expected immediate and none was found");
    (void)Success;
    MCInst TmpInst;
    if (Imm == 0) {
      TmpInst.setOpcode(Hexagon::A2_tfr);
      TmpInst.addOperand(MappedInst.getOperand(0));
      TmpInst.addOperand(MappedInst.getOperand(1));
      MappedInst = TmpInst;
      return;
    }
    TmpInst.setOpcode(Hexagon::S2_asr_i_r_rnd);
    TmpInst.addOperand(MappedInst.getOperand(0));
    TmpInst.addOperand(MappedInst.getOperand(1));
    const MCExpr *One = MCConstantExpr::create(1, OutContext);
    const MCExpr *Sub = MCBinaryExpr::createSub(Expr, One, OutContext);
    TmpInst.addOperand(
        MCOperand::createExpr(HexagonMCExpr::create(Sub, OutContext)));
    MappedInst = TmpInst;
    return;
  }
  case Hexagon::TFRI_f:
    MappedInst.setOpcode(Hexagon::A2_tfrsi);
    return;
  case Hexagon::TFRI_cPt_f:
    MappedInst.setOpcode(Hexagon::C2_cmoveit);
    return;
  case Hexagon::TFRI_cNotPt_f:
    MappedInst.setOpcode(Hexagon::C2_cmoveif);
    return;
  case Hexagon::MUX_ri_f:
    MappedInst.setOpcode(Hexagon::C2_muxri);
    return;
  case Hexagon::MUX_ir_f:
    MappedInst.setOpcode(Hexagon::C2_muxir);
    return;

  // Translate a "$Rdd = #imm" to "$Rdd = combine(#[-1,0], #imm)"
  case Hexagon::A2_tfrpi: {
    MCInst TmpInst;
    MCOperand &Rdd = MappedInst.getOperand(0);
    MCOperand &MO = MappedInst.getOperand(1);

    TmpInst.setOpcode(Hexagon::A2_combineii);
    TmpInst.addOperand(Rdd);
    int64_t Imm;
    bool Success = MO.getExpr()->evaluateAsAbsolute(Imm);
    if (Success && Imm < 0) {
      const MCExpr *MOne = MCConstantExpr::create(-1, OutContext);
      TmpInst.addOperand(MCOperand::createExpr(HexagonMCExpr::create(MOne, OutContext)));
    } else {
      const MCExpr *Zero = MCConstantExpr::create(0, OutContext);
      TmpInst.addOperand(MCOperand::createExpr(HexagonMCExpr::create(Zero, OutContext)));
    }
    TmpInst.addOperand(MO);
    MappedInst = TmpInst;
    return;
  }
  // Translate a "$Rdd = $Rss" to "$Rdd = combine($Rs, $Rt)"
  case Hexagon::A2_tfrp: {
    MCOperand &MO = MappedInst.getOperand(1);
    unsigned High = RI->getSubReg(MO.getReg(), Hexagon::subreg_hireg);
    unsigned Low = RI->getSubReg(MO.getReg(), Hexagon::subreg_loreg);
    MO.setReg(High);
    // Add a new operand for the second register in the pair.
    MappedInst.addOperand(MCOperand::createReg(Low));
    MappedInst.setOpcode(Hexagon::A2_combinew);
    return;
  }

  case Hexagon::A2_tfrpt:
  case Hexagon::A2_tfrpf: {
    MCOperand &MO = MappedInst.getOperand(2);
    unsigned High = RI->getSubReg(MO.getReg(), Hexagon::subreg_hireg);
    unsigned Low = RI->getSubReg(MO.getReg(), Hexagon::subreg_loreg);
    MO.setReg(High);
    // Add a new operand for the second register in the pair.
    MappedInst.addOperand(MCOperand::createReg(Low));
    MappedInst.setOpcode((Inst.getOpcode() == Hexagon::A2_tfrpt)
                          ? Hexagon::C2_ccombinewt
                          : Hexagon::C2_ccombinewf);
    return;
  }
  case Hexagon::A2_tfrptnew:
  case Hexagon::A2_tfrpfnew: {
    MCOperand &MO = MappedInst.getOperand(2);
    unsigned High = RI->getSubReg(MO.getReg(), Hexagon::subreg_hireg);
    unsigned Low = RI->getSubReg(MO.getReg(), Hexagon::subreg_loreg);
    MO.setReg(High);
    // Add a new operand for the second register in the pair.
    MappedInst.addOperand(MCOperand::createReg(Low));
    MappedInst.setOpcode((Inst.getOpcode() == Hexagon::A2_tfrptnew)
                          ? Hexagon::C2_ccombinewnewt
                          : Hexagon::C2_ccombinewnewf);
    return;
  }

  case Hexagon::M2_mpysmi: {
    MCOperand &Imm = MappedInst.getOperand(2);
    MCExpr const *Expr = Imm.getExpr();
    int64_t Value;
    bool Success = Expr->evaluateAsAbsolute(Value);
    assert(Success);
    (void)Success;
    if (Value < 0 && Value > -256) {
      MappedInst.setOpcode(Hexagon::M2_mpysin);
      Imm.setExpr(HexagonMCExpr::create(
          MCUnaryExpr::createMinus(Expr, OutContext), OutContext));
    } else
      MappedInst.setOpcode(Hexagon::M2_mpysip);
    return;
  }

  case Hexagon::A2_addsp: {
    MCOperand &Rt = Inst.getOperand(1);
    assert (Rt.isReg() && "Expected register and none was found");
    unsigned Reg = RI->getEncodingValue(Rt.getReg());
    if (Reg & 1)
      MappedInst.setOpcode(Hexagon::A2_addsph);
    else
      MappedInst.setOpcode(Hexagon::A2_addspl);
    Rt.setReg(getHexagonRegisterPair(Rt.getReg(), RI));
    return;
  }
  case Hexagon::HEXAGON_V6_vd0_pseudo:
  case Hexagon::HEXAGON_V6_vd0_pseudo_128B: {
    MCInst TmpInst;
    assert (Inst.getOperand(0).isReg() &&
            "Expected register and none was found");

    TmpInst.setOpcode(Hexagon::V6_vxor);
    TmpInst.addOperand(Inst.getOperand(0));
    TmpInst.addOperand(Inst.getOperand(0));
    TmpInst.addOperand(Inst.getOperand(0));
    MappedInst = TmpInst;
    return;
  }

  }
}


/// printMachineInstruction -- Print out a single Hexagon MI in Darwin syntax to
/// the current output stream.
///
void HexagonAsmPrinter::EmitInstruction(const MachineInstr *MI) {
  MCInst MCB = HexagonMCInstrInfo::createBundle();
  const MCInstrInfo &MCII = *Subtarget->getInstrInfo();

  if (MI->isBundle()) {
    const MachineBasicBlock* MBB = MI->getParent();
    MachineBasicBlock::const_instr_iterator MII = MI->getIterator();
    unsigned IgnoreCount = 0;

    for (++MII; MII != MBB->instr_end() && MII->isInsideBundle(); ++MII)
      if (MII->getOpcode() == TargetOpcode::DBG_VALUE ||
          MII->getOpcode() == TargetOpcode::IMPLICIT_DEF)
        ++IgnoreCount;
      else
        HexagonLowerToMC(MCII, &*MII, MCB, *this);
  }
  else
    HexagonLowerToMC(MCII, MI, MCB, *this);

  bool Ok = HexagonMCInstrInfo::canonicalizePacket(
      MCII, *Subtarget, OutStreamer->getContext(), MCB, nullptr);
  assert(Ok);
  (void)Ok;
  if(HexagonMCInstrInfo::bundleSize(MCB) == 0)
    return;
  OutStreamer->EmitInstruction(MCB, getSubtargetInfo());
}

extern "C" void LLVMInitializeHexagonAsmPrinter() {
  RegisterAsmPrinter<HexagonAsmPrinter> X(TheHexagonTarget);
}