llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp

//===-- X86AsmParser.cpp - Parse X86 assembly to MCInst instructions ------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "llvm/Target/TargetAsmParser.h"
#include "X86.h"
#include "X86Subtarget.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/ADT/Twine.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCParser/MCAsmLexer.h"
#include "llvm/MC/MCParser/MCAsmParser.h"
#include "llvm/MC/MCParser/MCParsedAsmOperand.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetRegistry.h"
#include "llvm/Target/TargetAsmParser.h"
using namespace llvm;

namespace {
struct X86Operand;

class X86ATTAsmParser : public TargetAsmParser {
  MCAsmParser &Parser;
  TargetMachine &TM;

protected:
  unsigned Is64Bit : 1;

private:
  MCAsmParser &getParser() const { return Parser; }

  MCAsmLexer &getLexer() const { return Parser.getLexer(); }

  bool Error(SMLoc L, const Twine &Msg) { return Parser.Error(L, Msg); }

  bool ParseRegister(unsigned &RegNo, SMLoc &StartLoc, SMLoc &EndLoc);

  X86Operand *ParseOperand();
  X86Operand *ParseMemOperand(unsigned SegReg, SMLoc StartLoc);

  bool ParseDirectiveWord(unsigned Size, SMLoc L);

  bool MatchInstruction(SMLoc IDLoc,
                        const SmallVectorImpl<MCParsedAsmOperand*> &Operands,
                        MCInst &Inst);

  /// @name Auto-generated Matcher Functions
  /// {
  
#define GET_ASSEMBLER_HEADER
#include "X86GenAsmMatcher.inc"
  
  /// }

public:
  X86ATTAsmParser(const Target &T, MCAsmParser &_Parser, TargetMachine &TM)
    : TargetAsmParser(T), Parser(_Parser), TM(TM) {

    // Initialize the set of available features.
    setAvailableFeatures(ComputeAvailableFeatures(
                           &TM.getSubtarget<X86Subtarget>()));
  }

  virtual bool ParseInstruction(StringRef Name, SMLoc NameLoc,
                                SmallVectorImpl<MCParsedAsmOperand*> &Operands);

  virtual bool ParseDirective(AsmToken DirectiveID);
};

class X86_32ATTAsmParser : public X86ATTAsmParser {
public:
  X86_32ATTAsmParser(const Target &T, MCAsmParser &_Parser, TargetMachine &TM)
    : X86ATTAsmParser(T, _Parser, TM) {
    Is64Bit = false;
  }
};

class X86_64ATTAsmParser : public X86ATTAsmParser {
public:
  X86_64ATTAsmParser(const Target &T, MCAsmParser &_Parser, TargetMachine &TM)
    : X86ATTAsmParser(T, _Parser, TM) {
    Is64Bit = true;
  }
};

} // end anonymous namespace

/// @name Auto-generated Match Functions
/// {

static unsigned MatchRegisterName(StringRef Name);

/// }

namespace {

/// X86Operand - Instances of this class represent a parsed X86 machine
/// instruction.
struct X86Operand : public MCParsedAsmOperand {
  enum KindTy {
    Token,
    Register,
    Immediate,
    Memory
  } Kind;

  SMLoc StartLoc, EndLoc;

  union {
    struct {
      const char *Data;
      unsigned Length;
    } Tok;

    struct {
      unsigned RegNo;
    } Reg;

    struct {
      const MCExpr *Val;
    } Imm;

    struct {
      unsigned SegReg;
      const MCExpr *Disp;
      unsigned BaseReg;
      unsigned IndexReg;
      unsigned Scale;
    } Mem;
  };

  X86Operand(KindTy K, SMLoc Start, SMLoc End)
    : Kind(K), StartLoc(Start), EndLoc(End) {}

  /// getStartLoc - Get the location of the first token of this operand.
  SMLoc getStartLoc() const { return StartLoc; }
  /// getEndLoc - Get the location of the last token of this operand.
  SMLoc getEndLoc() const { return EndLoc; }

  virtual void dump(raw_ostream &OS) const {}

  StringRef getToken() const {
    assert(Kind == Token && "Invalid access!");
    return StringRef(Tok.Data, Tok.Length);
  }
  void setTokenValue(StringRef Value) {
    assert(Kind == Token && "Invalid access!");
    Tok.Data = Value.data();
    Tok.Length = Value.size();
  }

  unsigned getReg() const {
    assert(Kind == Register && "Invalid access!");
    return Reg.RegNo;
  }

  const MCExpr *getImm() const {
    assert(Kind == Immediate && "Invalid access!");
    return Imm.Val;
  }

  const MCExpr *getMemDisp() const {
    assert(Kind == Memory && "Invalid access!");
    return Mem.Disp;
  }
  unsigned getMemSegReg() const {
    assert(Kind == Memory && "Invalid access!");
    return Mem.SegReg;
  }
  unsigned getMemBaseReg() const {
    assert(Kind == Memory && "Invalid access!");
    return Mem.BaseReg;
  }
  unsigned getMemIndexReg() const {
    assert(Kind == Memory && "Invalid access!");
    return Mem.IndexReg;
  }
  unsigned getMemScale() const {
    assert(Kind == Memory && "Invalid access!");
    return Mem.Scale;
  }

  bool isToken() const {return Kind == Token; }

  bool isImm() const { return Kind == Immediate; }

  bool isImmSExti16i8() const {
    if (!isImm())
      return false;

    // If this isn't a constant expr, just assume it fits and let relaxation
    // handle it.
    const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
    if (!CE)
      return true;

    // Otherwise, check the value is in a range that makes sense for this
    // extension.
    uint64_t Value = CE->getValue();
    return ((                                  Value <= 0x000000000000007FULL)||
            (0x000000000000FF80ULL <= Value && Value <= 0x000000000000FFFFULL)||
            (0xFFFFFFFFFFFFFF80ULL <= Value && Value <= 0xFFFFFFFFFFFFFFFFULL));
  }
  bool isImmSExti32i8() const {
    if (!isImm())
      return false;

    // If this isn't a constant expr, just assume it fits and let relaxation
    // handle it.
    const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
    if (!CE)
      return true;

    // Otherwise, check the value is in a range that makes sense for this
    // extension.
    uint64_t Value = CE->getValue();
    return ((                                  Value <= 0x000000000000007FULL)||
            (0x00000000FFFFFF80ULL <= Value && Value <= 0x00000000FFFFFFFFULL)||
            (0xFFFFFFFFFFFFFF80ULL <= Value && Value <= 0xFFFFFFFFFFFFFFFFULL));
  }
  bool isImmSExti64i8() const {
    if (!isImm())
      return false;

    // If this isn't a constant expr, just assume it fits and let relaxation
    // handle it.
    const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
    if (!CE)
      return true;

    // Otherwise, check the value is in a range that makes sense for this
    // extension.
    uint64_t Value = CE->getValue();
    return ((                                  Value <= 0x000000000000007FULL)||
            (0xFFFFFFFFFFFFFF80ULL <= Value && Value <= 0xFFFFFFFFFFFFFFFFULL));
  }
  bool isImmSExti64i32() const {
    if (!isImm())
      return false;

    // If this isn't a constant expr, just assume it fits and let relaxation
    // handle it.
    const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
    if (!CE)
      return true;

    // Otherwise, check the value is in a range that makes sense for this
    // extension.
    uint64_t Value = CE->getValue();
    return ((                                  Value <= 0x000000007FFFFFFFULL)||
            (0xFFFFFFFF80000000ULL <= Value && Value <= 0xFFFFFFFFFFFFFFFFULL));
  }

  bool isMem() const { return Kind == Memory; }

  bool isAbsMem() const {
    return Kind == Memory && !getMemSegReg() && !getMemBaseReg() &&
      !getMemIndexReg() && getMemScale() == 1;
  }

  bool isReg() const { return Kind == Register; }

  void addExpr(MCInst &Inst, const MCExpr *Expr) const {
    // Add as immediates when possible.
    if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(Expr))
      Inst.addOperand(MCOperand::CreateImm(CE->getValue()));
    else
      Inst.addOperand(MCOperand::CreateExpr(Expr));
  }

  void addRegOperands(MCInst &Inst, unsigned N) const {
    assert(N == 1 && "Invalid number of operands!");
    Inst.addOperand(MCOperand::CreateReg(getReg()));
  }

  void addImmOperands(MCInst &Inst, unsigned N) const {
    assert(N == 1 && "Invalid number of operands!");
    addExpr(Inst, getImm());
  }

  void addMemOperands(MCInst &Inst, unsigned N) const {
    assert((N == 5) && "Invalid number of operands!");
    Inst.addOperand(MCOperand::CreateReg(getMemBaseReg()));
    Inst.addOperand(MCOperand::CreateImm(getMemScale()));
    Inst.addOperand(MCOperand::CreateReg(getMemIndexReg()));
    addExpr(Inst, getMemDisp());
    Inst.addOperand(MCOperand::CreateReg(getMemSegReg()));
  }

  void addAbsMemOperands(MCInst &Inst, unsigned N) const {
    assert((N == 1) && "Invalid number of operands!");
    Inst.addOperand(MCOperand::CreateExpr(getMemDisp()));
  }

  static X86Operand *CreateToken(StringRef Str, SMLoc Loc) {
    X86Operand *Res = new X86Operand(Token, Loc, Loc);
    Res->Tok.Data = Str.data();
    Res->Tok.Length = Str.size();
    return Res;
  }

  static X86Operand *CreateReg(unsigned RegNo, SMLoc StartLoc, SMLoc EndLoc) {
    X86Operand *Res = new X86Operand(Register, StartLoc, EndLoc);
    Res->Reg.RegNo = RegNo;
    return Res;
  }

  static X86Operand *CreateImm(const MCExpr *Val, SMLoc StartLoc, SMLoc EndLoc){
    X86Operand *Res = new X86Operand(Immediate, StartLoc, EndLoc);
    Res->Imm.Val = Val;
    return Res;
  }

  /// Create an absolute memory operand.
  static X86Operand *CreateMem(const MCExpr *Disp, SMLoc StartLoc,
                               SMLoc EndLoc) {
    X86Operand *Res = new X86Operand(Memory, StartLoc, EndLoc);
    Res->Mem.SegReg   = 0;
    Res->Mem.Disp     = Disp;
    Res->Mem.BaseReg  = 0;
    Res->Mem.IndexReg = 0;
    Res->Mem.Scale    = 1;
    return Res;
  }

  /// Create a generalized memory operand.
  static X86Operand *CreateMem(unsigned SegReg, const MCExpr *Disp,
                               unsigned BaseReg, unsigned IndexReg,
                               unsigned Scale, SMLoc StartLoc, SMLoc EndLoc) {
    // We should never just have a displacement, that should be parsed as an
    // absolute memory operand.
    assert((SegReg || BaseReg || IndexReg) && "Invalid memory operand!");

    // The scale should always be one of {1,2,4,8}.
    assert(((Scale == 1 || Scale == 2 || Scale == 4 || Scale == 8)) &&
           "Invalid scale!");
    X86Operand *Res = new X86Operand(Memory, StartLoc, EndLoc);
    Res->Mem.SegReg   = SegReg;
    Res->Mem.Disp     = Disp;
    Res->Mem.BaseReg  = BaseReg;
    Res->Mem.IndexReg = IndexReg;
    Res->Mem.Scale    = Scale;
    return Res;
  }
};

} // end anonymous namespace.


bool X86ATTAsmParser::ParseRegister(unsigned &RegNo,
                                    SMLoc &StartLoc, SMLoc &EndLoc) {
  RegNo = 0;
  const AsmToken &TokPercent = Parser.getTok();
  assert(TokPercent.is(AsmToken::Percent) && "Invalid token kind!");
  StartLoc = TokPercent.getLoc();
  Parser.Lex(); // Eat percent token.

  const AsmToken &Tok = Parser.getTok();
  if (Tok.isNot(AsmToken::Identifier))
    return Error(Tok.getLoc(), "invalid register name");

  // FIXME: Validate register for the current architecture; we have to do
  // validation later, so maybe there is no need for this here.
  RegNo = MatchRegisterName(Tok.getString());

  // FIXME: This should be done using Requires<In32BitMode> and
  // Requires<In64BitMode> so "eiz" usage in 64-bit instructions
  // can be also checked.
  if (RegNo == X86::RIZ && !Is64Bit)
    return Error(Tok.getLoc(), "riz register in 64-bit mode only");

  // Parse %st(1) and "%st" as "%st(0)"
  if (RegNo == 0 && Tok.getString() == "st") {
    RegNo = X86::ST0;
    EndLoc = Tok.getLoc();
    Parser.Lex(); // Eat 'st'

    // Check to see if we have '(4)' after %st.
    if (getLexer().isNot(AsmToken::LParen))
      return false;
    // Lex the paren.
    getParser().Lex();

    const AsmToken &IntTok = Parser.getTok();
    if (IntTok.isNot(AsmToken::Integer))
      return Error(IntTok.getLoc(), "expected stack index");
    switch (IntTok.getIntVal()) {
    case 0: RegNo = X86::ST0; break;
    case 1: RegNo = X86::ST1; break;
    case 2: RegNo = X86::ST2; break;
    case 3: RegNo = X86::ST3; break;
    case 4: RegNo = X86::ST4; break;
    case 5: RegNo = X86::ST5; break;
    case 6: RegNo = X86::ST6; break;
    case 7: RegNo = X86::ST7; break;
    default: return Error(IntTok.getLoc(), "invalid stack index");
    }

    if (getParser().Lex().isNot(AsmToken::RParen))
      return Error(Parser.getTok().getLoc(), "expected ')'");

    EndLoc = Tok.getLoc();
    Parser.Lex(); // Eat ')'
    return false;
  }

  // If this is "db[0-7]", match it as an alias
  // for dr[0-7].
  if (RegNo == 0 && Tok.getString().size() == 3 &&
      Tok.getString().startswith("db")) {
    switch (Tok.getString()[2]) {
    case '0': RegNo = X86::DR0; break;
    case '1': RegNo = X86::DR1; break;
    case '2': RegNo = X86::DR2; break;
    case '3': RegNo = X86::DR3; break;
    case '4': RegNo = X86::DR4; break;
    case '5': RegNo = X86::DR5; break;
    case '6': RegNo = X86::DR6; break;
    case '7': RegNo = X86::DR7; break;
    }

    if (RegNo != 0) {
      EndLoc = Tok.getLoc();
      Parser.Lex(); // Eat it.
      return false;
    }
  }

  if (RegNo == 0)
    return Error(Tok.getLoc(), "invalid register name");

  EndLoc = Tok.getLoc();
  Parser.Lex(); // Eat identifier token.
  return false;
}

X86Operand *X86ATTAsmParser::ParseOperand() {
  switch (getLexer().getKind()) {
  default:
    // Parse a memory operand with no segment register.
    return ParseMemOperand(0, Parser.getTok().getLoc());
  case AsmToken::Percent: {
    // Read the register.
    unsigned RegNo;
    SMLoc Start, End;
    if (ParseRegister(RegNo, Start, End)) return 0;
    if (RegNo == X86::EIZ || RegNo == X86::RIZ) {
      Error(Start, "eiz and riz can only be used as index registers");
      return 0;
    }

    // If this is a segment register followed by a ':', then this is the start
    // of a memory reference, otherwise this is a normal register reference.
    if (getLexer().isNot(AsmToken::Colon))
      return X86Operand::CreateReg(RegNo, Start, End);


    getParser().Lex(); // Eat the colon.
    return ParseMemOperand(RegNo, Start);
  }
  case AsmToken::Dollar: {
    // $42 -> immediate.
    SMLoc Start = Parser.getTok().getLoc(), End;
    Parser.Lex();
    const MCExpr *Val;
    if (getParser().ParseExpression(Val, End))
      return 0;
    return X86Operand::CreateImm(Val, Start, End);
  }
  }
}

/// ParseMemOperand: segment: disp(basereg, indexreg, scale).  The '%ds:' prefix
/// has already been parsed if present.
X86Operand *X86ATTAsmParser::ParseMemOperand(unsigned SegReg, SMLoc MemStart) {

  // We have to disambiguate a parenthesized expression "(4+5)" from the start
  // of a memory operand with a missing displacement "(%ebx)" or "(,%eax)".  The
  // only way to do this without lookahead is to eat the '(' and see what is
  // after it.
  const MCExpr *Disp = MCConstantExpr::Create(0, getParser().getContext());
  if (getLexer().isNot(AsmToken::LParen)) {
    SMLoc ExprEnd;
    if (getParser().ParseExpression(Disp, ExprEnd)) return 0;

    // After parsing the base expression we could either have a parenthesized
    // memory address or not.  If not, return now.  If so, eat the (.
    if (getLexer().isNot(AsmToken::LParen)) {
      // Unless we have a segment register, treat this as an immediate.
      if (SegReg == 0)
        return X86Operand::CreateMem(Disp, MemStart, ExprEnd);
      return X86Operand::CreateMem(SegReg, Disp, 0, 0, 1, MemStart, ExprEnd);
    }

    // Eat the '('.
    Parser.Lex();
  } else {
    // Okay, we have a '('.  We don't know if this is an expression or not, but
    // so we have to eat the ( to see beyond it.
    SMLoc LParenLoc = Parser.getTok().getLoc();
    Parser.Lex(); // Eat the '('.

    if (getLexer().is(AsmToken::Percent) || getLexer().is(AsmToken::Comma)) {
      // Nothing to do here, fall into the code below with the '(' part of the
      // memory operand consumed.
    } else {
      SMLoc ExprEnd;

      // It must be an parenthesized expression, parse it now.
      if (getParser().ParseParenExpression(Disp, ExprEnd))
        return 0;

      // After parsing the base expression we could either have a parenthesized
      // memory address or not.  If not, return now.  If so, eat the (.
      if (getLexer().isNot(AsmToken::LParen)) {
        // Unless we have a segment register, treat this as an immediate.
        if (SegReg == 0)
          return X86Operand::CreateMem(Disp, LParenLoc, ExprEnd);
        return X86Operand::CreateMem(SegReg, Disp, 0, 0, 1, MemStart, ExprEnd);
      }

      // Eat the '('.
      Parser.Lex();
    }
  }

  // If we reached here, then we just ate the ( of the memory operand.  Process
  // the rest of the memory operand.
  unsigned BaseReg = 0, IndexReg = 0, Scale = 1;

  if (getLexer().is(AsmToken::Percent)) {
    SMLoc L;
    if (ParseRegister(BaseReg, L, L)) return 0;
    if (BaseReg == X86::EIZ || BaseReg == X86::RIZ) {
      Error(L, "eiz and riz can only be used as index registers");
      return 0;
    }
  }

  if (getLexer().is(AsmToken::Comma)) {
    Parser.Lex(); // Eat the comma.

    // Following the comma we should have either an index register, or a scale
    // value. We don't support the later form, but we want to parse it
    // correctly.
    //
    // Not that even though it would be completely consistent to support syntax
    // like "1(%eax,,1)", the assembler doesn't. Use "eiz" or "riz" for this.
    if (getLexer().is(AsmToken::Percent)) {
      SMLoc L;
      if (ParseRegister(IndexReg, L, L)) return 0;

      if (getLexer().isNot(AsmToken::RParen)) {
        // Parse the scale amount:
        //  ::= ',' [scale-expression]
        if (getLexer().isNot(AsmToken::Comma)) {
          Error(Parser.getTok().getLoc(),
                "expected comma in scale expression");
          return 0;
        }
        Parser.Lex(); // Eat the comma.

        if (getLexer().isNot(AsmToken::RParen)) {
          SMLoc Loc = Parser.getTok().getLoc();

          int64_t ScaleVal;
          if (getParser().ParseAbsoluteExpression(ScaleVal))
            return 0;

          // Validate the scale amount.
          if (ScaleVal != 1 && ScaleVal != 2 && ScaleVal != 4 && ScaleVal != 8){
            Error(Loc, "scale factor in address must be 1, 2, 4 or 8");
            return 0;
          }
          Scale = (unsigned)ScaleVal;
        }
      }
    } else if (getLexer().isNot(AsmToken::RParen)) {
      // A scale amount without an index is ignored.
      // index.
      SMLoc Loc = Parser.getTok().getLoc();

      int64_t Value;
      if (getParser().ParseAbsoluteExpression(Value))
        return 0;

      if (Value != 1)
        Warning(Loc, "scale factor without index register is ignored");
      Scale = 1;
    }
  }

  // Ok, we've eaten the memory operand, verify we have a ')' and eat it too.
  if (getLexer().isNot(AsmToken::RParen)) {
    Error(Parser.getTok().getLoc(), "unexpected token in memory operand");
    return 0;
  }
  SMLoc MemEnd = Parser.getTok().getLoc();
  Parser.Lex(); // Eat the ')'.

  return X86Operand::CreateMem(SegReg, Disp, BaseReg, IndexReg, Scale,
                               MemStart, MemEnd);
}

bool X86ATTAsmParser::
ParseInstruction(StringRef Name, SMLoc NameLoc,
                 SmallVectorImpl<MCParsedAsmOperand*> &Operands) {

  // The "Jump if rCX Zero" form jcxz is not allowed in 64-bit mode and
  // the form jrcxz is not allowed in 32-bit mode.
  if (Is64Bit) {
    // FIXME: We can do jcxz/jecxz, we just don't have the encoding right yet.
    if (Name == "jcxz" || Name == "jecxz")
      return Error(NameLoc, Name + " cannot be encoded in 64-bit mode");
  } else {
    if (Name == "jrcxz")
      return Error(NameLoc, "jrcxz cannot be encoded in 32-bit mode");
  }

  // FIXME: Hack to recognize "sal..." and "rep..." for now. We need a way to
  // represent alternative syntaxes in the .td file, without requiring
  // instruction duplication.
  StringRef PatchedName = StringSwitch<StringRef>(Name)
    .Case("sal", "shl")
    .Case("salb", "shlb")
    .Case("sall", "shll")
    .Case("salq", "shlq")
    .Case("salw", "shlw")
    .Case("repe", "rep")
    .Case("repz", "rep")
    .Case("repnz", "repne")
    .Case("pushf", Is64Bit ? "pushfq" : "pushfl")
    .Case("popf",  Is64Bit ? "popfq"  : "popfl")
    .Case("retl", Is64Bit ? "retl" : "ret")
    .Case("retq", Is64Bit ? "ret" : "retq")
    .Case("setz", "sete")
    .Case("setnz", "setne")
    .Case("jz", "je")
    .Case("jnz", "jne")
    .Case("jc", "jb")
    // FIXME: in 32-bit mode jcxz requires an AdSize prefix. In 64-bit mode
    // jecxz requires an AdSize prefix but jecxz does not have a prefix in
    // 32-bit mode.
    .Case("jecxz", "jcxz")
    .Case("jrcxz", "jcxz")
    .Case("jna", "jbe")
    .Case("jnae", "jb")
    .Case("jnb", "jae")
    .Case("jnbe", "ja")
    .Case("jnc", "jae")
    .Case("jng", "jle")
    .Case("jnge", "jl")
    .Case("jnl", "jge")
    .Case("jnle", "jg")
    .Case("jpe", "jp")
    .Case("jpo", "jnp")
    .Case("cmovcl", "cmovbl")
    .Case("cmovcl", "cmovbl")
    .Case("cmovnal", "cmovbel")
    .Case("cmovnbl", "cmovael")
    .Case("cmovnbel", "cmoval")
    .Case("cmovncl", "cmovael")
    .Case("cmovngl", "cmovlel")
    .Case("cmovnl", "cmovgel")
    .Case("cmovngl", "cmovlel")
    .Case("cmovngel", "cmovll")
    .Case("cmovnll", "cmovgel")
    .Case("cmovnlel", "cmovgl")
    .Case("cmovnzl", "cmovnel")
    .Case("cmovzl", "cmovel")
    .Case("fwait", "wait")
    .Case("movzx", "movzb")
    .Default(Name);

  // FIXME: Hack to recognize cmp<comparison code>{ss,sd,ps,pd}.
  const MCExpr *ExtraImmOp = 0;
  if ((PatchedName.startswith("cmp") || PatchedName.startswith("vcmp")) &&
      (PatchedName.endswith("ss") || PatchedName.endswith("sd") ||
       PatchedName.endswith("ps") || PatchedName.endswith("pd"))) {
    bool IsVCMP = PatchedName.startswith("vcmp");
    unsigned SSECCIdx = IsVCMP ? 4 : 3;
    unsigned SSEComparisonCode = StringSwitch<unsigned>(
      PatchedName.slice(SSECCIdx, PatchedName.size() - 2))
      .Case("eq",          0)
      .Case("lt",          1)
      .Case("le",          2)
      .Case("unord",       3)
      .Case("neq",         4)
      .Case("nlt",         5)
      .Case("nle",         6)
      .Case("ord",         7)
      .Case("eq_uq",       8)
      .Case("nge",         9)
      .Case("ngt",      0x0A)
      .Case("false",    0x0B)
      .Case("neq_oq",   0x0C)
      .Case("ge",       0x0D)
      .Case("gt",       0x0E)
      .Case("true",     0x0F)
      .Case("eq_os",    0x10)
      .Case("lt_oq",    0x11)
      .Case("le_oq",    0x12)
      .Case("unord_s",  0x13)
      .Case("neq_us",   0x14)
      .Case("nlt_uq",   0x15)
      .Case("nle_uq",   0x16)
      .Case("ord_s",    0x17)
      .Case("eq_us",    0x18)
      .Case("nge_uq",   0x19)
      .Case("ngt_uq",   0x1A)
      .Case("false_os", 0x1B)
      .Case("neq_os",   0x1C)
      .Case("ge_oq",    0x1D)
      .Case("gt_oq",    0x1E)
      .Case("true_us",  0x1F)
      .Default(~0U);
    if (SSEComparisonCode != ~0U) {
      ExtraImmOp = MCConstantExpr::Create(SSEComparisonCode,
                                          getParser().getContext());
      if (PatchedName.endswith("ss")) {
        PatchedName = IsVCMP ? "vcmpss" : "cmpss";
      } else if (PatchedName.endswith("sd")) {
        PatchedName = IsVCMP ? "vcmpsd" : "cmpsd";
      } else if (PatchedName.endswith("ps")) {
        PatchedName = IsVCMP ? "vcmpps" : "cmpps";
      } else {
        assert(PatchedName.endswith("pd") && "Unexpected mnemonic!");
        PatchedName = IsVCMP ? "vcmppd" : "cmppd";
      }
    }
  }

  // FIXME: Hack to recognize vpclmul<src1_quadword, src2_quadword>dq
  if (PatchedName.startswith("vpclmul")) {
    unsigned CLMULQuadWordSelect = StringSwitch<unsigned>(
      PatchedName.slice(7, PatchedName.size() - 2))
      .Case("lqlq", 0x00) // src1[63:0],   src2[63:0]
      .Case("hqlq", 0x01) // src1[127:64], src2[63:0]
      .Case("lqhq", 0x10) // src1[63:0],   src2[127:64]
      .Case("hqhq", 0x11) // src1[127:64], src2[127:64]
      .Default(~0U);
    if (CLMULQuadWordSelect != ~0U) {
      ExtraImmOp = MCConstantExpr::Create(CLMULQuadWordSelect,
                                          getParser().getContext());
      assert(PatchedName.endswith("dq") && "Unexpected mnemonic!");
      PatchedName = "vpclmulqdq";
    }
  }
  Operands.push_back(X86Operand::CreateToken(PatchedName, NameLoc));

  if (ExtraImmOp)
    Operands.push_back(X86Operand::CreateImm(ExtraImmOp, NameLoc, NameLoc));

  
  // This does the actual operand parsing.
  if (getLexer().isNot(AsmToken::EndOfStatement)) {

    // Parse '*' modifier.
    if (getLexer().is(AsmToken::Star)) {
      SMLoc Loc = Parser.getTok().getLoc();
      Operands.push_back(X86Operand::CreateToken("*", Loc));
      Parser.Lex(); // Eat the star.
    }

    // Read the first operand.
    if (X86Operand *Op = ParseOperand())
      Operands.push_back(Op);
    else
      return true;

    while (getLexer().is(AsmToken::Comma)) {
      Parser.Lex();  // Eat the comma.

      // Parse and remember the operand.
      if (X86Operand *Op = ParseOperand())
        Operands.push_back(Op);
      else
        return true;
    }
  }

  // FIXME: Hack to handle recognizing s{hr,ar,hl}? $1.
  if ((Name.startswith("shr") || Name.startswith("sar") ||
       Name.startswith("shl")) &&
      Operands.size() == 3) {
    X86Operand *Op1 = static_cast<X86Operand*>(Operands[1]);
    if (Op1->isImm() && isa<MCConstantExpr>(Op1->getImm()) &&
        cast<MCConstantExpr>(Op1->getImm())->getValue() == 1) {
      delete Operands[1];
      Operands.erase(Operands.begin() + 1);
    }
  }

  // FIXME: Hack to handle "f{mul*,add*,sub*,div*} $op, st(0)" the same as
  // "f{mul*,add*,sub*,div*} $op"
  if ((Name.startswith("fmul") || Name.startswith("fadd") ||
       Name.startswith("fsub") || Name.startswith("fdiv")) &&
      Operands.size() == 3 &&
      static_cast<X86Operand*>(Operands[2])->isReg() &&
      static_cast<X86Operand*>(Operands[2])->getReg() == X86::ST0) {
    delete Operands[2];
    Operands.erase(Operands.begin() + 2);
  }

  // FIXME: Hack to handle "imul <imm>, B" which is an alias for "imul <imm>, B,
  // B".
  if (Name.startswith("imul") && Operands.size() == 3 &&
      static_cast<X86Operand*>(Operands[1])->isImm() &&
      static_cast<X86Operand*>(Operands.back())->isReg()) {
    X86Operand *Op = static_cast<X86Operand*>(Operands.back());
    Operands.push_back(X86Operand::CreateReg(Op->getReg(), Op->getStartLoc(),
                                             Op->getEndLoc()));
  }

  return false;
}

bool X86ATTAsmParser::ParseDirective(AsmToken DirectiveID) {
  StringRef IDVal = DirectiveID.getIdentifier();
  if (IDVal == ".word")
    return ParseDirectiveWord(2, DirectiveID.getLoc());
  return true;
}

/// ParseDirectiveWord
///  ::= .word [ expression (, expression)* ]
bool X86ATTAsmParser::ParseDirectiveWord(unsigned Size, SMLoc L) {
  if (getLexer().isNot(AsmToken::EndOfStatement)) {
    for (;;) {
      const MCExpr *Value;
      if (getParser().ParseExpression(Value))
        return true;

      getParser().getStreamer().EmitValue(Value, Size, 0 /*addrspace*/);

      if (getLexer().is(AsmToken::EndOfStatement))
        break;

      // FIXME: Improve diagnostic.
      if (getLexer().isNot(AsmToken::Comma))
        return Error(L, "unexpected token in directive");
      Parser.Lex();
    }
  }

  Parser.Lex();
  return false;
}


bool
X86ATTAsmParser::MatchInstruction(SMLoc IDLoc,
                                  const SmallVectorImpl<MCParsedAsmOperand*>
                                    &Operands,
                                  MCInst &Inst) {
  assert(!Operands.empty() && "Unexpect empty operand list!");

  // First, try a direct match.
  switch (MatchInstructionImpl(Operands, Inst)) {
  case Match_Success:
    return false;
  case Match_MissingFeature:
    Error(IDLoc, "instruction requires a CPU feature not currently enabled");
    return true;
  default:
    break;
  }

  // FIXME: Ideally, we would only attempt suffix matches for things which are
  // valid prefixes, and we could just infer the right unambiguous
  // type. However, that requires substantially more matcher support than the
  // following hack.

  X86Operand *Op = static_cast<X86Operand*>(Operands[0]);
  assert(Op->isToken() && "Leading operand should always be a mnemonic!");
  
  // Change the operand to point to a temporary token.
  StringRef Base = Op->getToken();
  SmallString<16> Tmp;
  Tmp += Base;
  Tmp += ' ';
  Op->setTokenValue(Tmp.str());

  // Check for the various suffix matches.
  Tmp[Base.size()] = 'b';
  MatchResultTy MatchB = MatchInstructionImpl(Operands, Inst);
  Tmp[Base.size()] = 'w';
  MatchResultTy MatchW = MatchInstructionImpl(Operands, Inst);
  Tmp[Base.size()] = 'l';
  MatchResultTy MatchL = MatchInstructionImpl(Operands, Inst);
  Tmp[Base.size()] = 'q';
  MatchResultTy MatchQ = MatchInstructionImpl(Operands, Inst);

  // Restore the old token.
  Op->setTokenValue(Base);

  // If exactly one matched, then we treat that as a successful match (and the
  // instruction will already have been filled in correctly, since the failing
  // matches won't have modified it).
  unsigned NumSuccessfulMatches =
    (MatchB == Match_Success) + (MatchW == Match_Success) +
    (MatchL == Match_Success) + (MatchQ == Match_Success);
  if (NumSuccessfulMatches == 1)
    return false;

  // Otherwise, the match failed, try to produce a decent error message.

  // If we had multiple suffix matches, then identify this as an ambiguous
  // match.
  if (NumSuccessfulMatches > 1) {
    char MatchChars[4];
    unsigned NumMatches = 0;
    if (MatchB == Match_Success)
      MatchChars[NumMatches++] = 'b';
    if (MatchW == Match_Success)
      MatchChars[NumMatches++] = 'w';
    if (MatchL == Match_Success)
      MatchChars[NumMatches++] = 'l';
    if (MatchQ == Match_Success)
      MatchChars[NumMatches++] = 'q';

    SmallString<126> Msg;
    raw_svector_ostream OS(Msg);
    OS << "ambiguous instructions require an explicit suffix (could be ";
    for (unsigned i = 0; i != NumMatches; ++i) {
      if (i != 0)
        OS << ", ";
      if (i + 1 == NumMatches)
        OS << "or ";
      OS << "'" << Base << MatchChars[i] << "'";
    }
    OS << ")";
    Error(IDLoc, OS.str());
    return true;
  }
  
  unsigned NumMatchFailures =
    (MatchB == Match_Fail) + (MatchW == Match_Fail) +
    (MatchL == Match_Fail) + (MatchQ == Match_Fail);
  
  
  // If one instruction matched with a missing feature, report this as a
  // missing feature.
  if ((MatchB == Match_MissingFeature) + (MatchW == Match_MissingFeature) +
      (MatchL == Match_MissingFeature) + (MatchQ == Match_MissingFeature) == 1&&
      NumMatchFailures == 3) {
    Error(IDLoc, "instruction requires a CPU feature not currently enabled");
    return true;
  }
  
  // If all of these were an outright failure, report it in a useless way.
  // FIXME: We should give nicer diagnostics about the exact failure.
  Error(IDLoc, "unrecognized instruction");
  return true;
}


extern "C" void LLVMInitializeX86AsmLexer();

// Force static initialization.
extern "C" void LLVMInitializeX86AsmParser() {
  RegisterAsmParser<X86_32ATTAsmParser> X(TheX86_32Target);
  RegisterAsmParser<X86_64ATTAsmParser> Y(TheX86_64Target);
  LLVMInitializeX86AsmLexer();
}

#define GET_REGISTER_MATCHER
#define GET_MATCHER_IMPLEMENTATION
#include "X86GenAsmMatcher.inc"