src/third_party/llvm-project/llvm/lib/MC/MCParser/AsmParser.cpp

//===- AsmParser.cpp - Parser for Assembly Files --------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This class implements the parser for assembly files.
//
//===----------------------------------------------------------------------===//

#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/None.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Twine.h"
#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCCodeView.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCDirectives.h"
#include "llvm/MC/MCDwarf.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInstPrinter.h"
#include "llvm/MC/MCInstrDesc.h"
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/MC/MCObjectFileInfo.h"
#include "llvm/MC/MCParser/AsmCond.h"
#include "llvm/MC/MCParser/AsmLexer.h"
#include "llvm/MC/MCParser/MCAsmLexer.h"
#include "llvm/MC/MCParser/MCAsmParser.h"
#include "llvm/MC/MCParser/MCAsmParserExtension.h"
#include "llvm/MC/MCParser/MCAsmParserUtils.h"
#include "llvm/MC/MCParser/MCParsedAsmOperand.h"
#include "llvm/MC/MCParser/MCTargetAsmParser.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCTargetOptions.h"
#include "llvm/MC/MCValue.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MD5.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/SMLoc.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
#include <cctype>
#include <climits>
#include <cstddef>
#include <cstdint>
#include <deque>
#include <memory>
#include <sstream>
#include <string>
#include <tuple>
#include <utility>
#include <vector>

using namespace llvm;

MCAsmParserSemaCallback::~MCAsmParserSemaCallback() = default;

static cl::opt<unsigned> AsmMacroMaxNestingDepth(
     "asm-macro-max-nesting-depth", cl::init(20), cl::Hidden,
     cl::desc("The maximum nesting depth allowed for assembly macros."));

namespace {

/// Helper types for tracking macro definitions.
typedef std::vector<AsmToken> MCAsmMacroArgument;
typedef std::vector<MCAsmMacroArgument> MCAsmMacroArguments;

/// Helper class for storing information about an active macro
/// instantiation.
struct MacroInstantiation {
  /// The location of the instantiation.
  SMLoc InstantiationLoc;

  /// The buffer where parsing should resume upon instantiation completion.
  int ExitBuffer;

  /// The location where parsing should resume upon instantiation completion.
  SMLoc ExitLoc;

  /// The depth of TheCondStack at the start of the instantiation.
  size_t CondStackDepth;

public:
  MacroInstantiation(SMLoc IL, int EB, SMLoc EL, size_t CondStackDepth);
};

struct ParseStatementInfo {
  /// The parsed operands from the last parsed statement.
  SmallVector<std::unique_ptr<MCParsedAsmOperand>, 8> ParsedOperands;

  /// The opcode from the last parsed instruction.
  unsigned Opcode = ~0U;

  /// Was there an error parsing the inline assembly?
  bool ParseError = false;

  SmallVectorImpl<AsmRewrite> *AsmRewrites = nullptr;

  ParseStatementInfo() = delete;
  ParseStatementInfo(SmallVectorImpl<AsmRewrite> *rewrites)
    : AsmRewrites(rewrites) {}
};

/// The concrete assembly parser instance.
class AsmParser : public MCAsmParser {
private:
  AsmLexer Lexer;
  MCContext &Ctx;
  MCStreamer &Out;
  const MCAsmInfo &MAI;
  SourceMgr &SrcMgr;
  SourceMgr::DiagHandlerTy SavedDiagHandler;
  void *SavedDiagContext;
  std::unique_ptr<MCAsmParserExtension> PlatformParser;

  /// This is the current buffer index we're lexing from as managed by the
  /// SourceMgr object.
  unsigned CurBuffer;

  AsmCond TheCondState;
  std::vector<AsmCond> TheCondStack;

  /// maps directive names to handler methods in parser
  /// extensions. Extensions register themselves in this map by calling
  /// addDirectiveHandler.
  StringMap<ExtensionDirectiveHandler> ExtensionDirectiveMap;

  /// Stack of active macro instantiations.
  std::vector<MacroInstantiation*> ActiveMacros;

  /// List of bodies of anonymous macros.
  std::deque<MCAsmMacro> MacroLikeBodies;

  /// Boolean tracking whether macro substitution is enabled.
  unsigned MacrosEnabledFlag : 1;

  /// Keeps track of how many .macro's have been instantiated.
  unsigned NumOfMacroInstantiations;

  /// The values from the last parsed cpp hash file line comment if any.
  struct CppHashInfoTy {
    StringRef Filename;
    int64_t LineNumber = 0;
    SMLoc Loc;
    unsigned Buf = 0;
  };
  CppHashInfoTy CppHashInfo;

  /// List of forward directional labels for diagnosis at the end.
  SmallVector<std::tuple<SMLoc, CppHashInfoTy, MCSymbol *>, 4> DirLabels;

  /// AssemblerDialect. ~OU means unset value and use value provided by MAI.
  unsigned AssemblerDialect = ~0U;

  /// is Darwin compatibility enabled?
  bool IsDarwin = false;

  /// Are we parsing ms-style inline assembly?
  bool ParsingInlineAsm = false;

  /// Did we already inform the user about inconsistent MD5 usage?
  bool ReportedInconsistentMD5 = false;

public:
  AsmParser(SourceMgr &SM, MCContext &Ctx, MCStreamer &Out,
            const MCAsmInfo &MAI, unsigned CB);
  AsmParser(const AsmParser &) = delete;
  AsmParser &operator=(const AsmParser &) = delete;
  ~AsmParser() override;

  bool Run(bool NoInitialTextSection, bool NoFinalize = false) override;

  void addDirectiveHandler(StringRef Directive,
                           ExtensionDirectiveHandler Handler) override {
    ExtensionDirectiveMap[Directive] = Handler;
  }

  void addAliasForDirective(StringRef Directive, StringRef Alias) override {
    DirectiveKindMap[Directive] = DirectiveKindMap[Alias];
  }

  /// @name MCAsmParser Interface
  /// {

  SourceMgr &getSourceManager() override { return SrcMgr; }
  MCAsmLexer &getLexer() override { return Lexer; }
  MCContext &getContext() override { return Ctx; }
  MCStreamer &getStreamer() override { return Out; }

  CodeViewContext &getCVContext() { return Ctx.getCVContext(); }

  unsigned getAssemblerDialect() override {
    if (AssemblerDialect == ~0U)
      return MAI.getAssemblerDialect();
    else
      return AssemblerDialect;
  }
  void setAssemblerDialect(unsigned i) override {
    AssemblerDialect = i;
  }

  void Note(SMLoc L, const Twine &Msg, SMRange Range = None) override;
  bool Warning(SMLoc L, const Twine &Msg, SMRange Range = None) override;
  bool printError(SMLoc L, const Twine &Msg, SMRange Range = None) override;

  const AsmToken &Lex() override;

  void setParsingInlineAsm(bool V) override {
    ParsingInlineAsm = V;
    Lexer.setParsingMSInlineAsm(V);
  }
  bool isParsingInlineAsm() override { return ParsingInlineAsm; }

  bool parseMSInlineAsm(void *AsmLoc, std::string &AsmString,
                        unsigned &NumOutputs, unsigned &NumInputs,
                        SmallVectorImpl<std::pair<void *,bool>> &OpDecls,
                        SmallVectorImpl<std::string> &Constraints,
                        SmallVectorImpl<std::string> &Clobbers,
                        const MCInstrInfo *MII, const MCInstPrinter *IP,
                        MCAsmParserSemaCallback &SI) override;

  bool parseExpression(const MCExpr *&Res);
  bool parseExpression(const MCExpr *&Res, SMLoc &EndLoc) override;
  bool parsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc) override;
  bool parseParenExpression(const MCExpr *&Res, SMLoc &EndLoc) override;
  bool parseParenExprOfDepth(unsigned ParenDepth, const MCExpr *&Res,
                             SMLoc &EndLoc) override;
  bool parseAbsoluteExpression(int64_t &Res) override;

  /// Parse a floating point expression using the float \p Semantics
  /// and set \p Res to the value.
  bool parseRealValue(const fltSemantics &Semantics, APInt &Res);

  /// Parse an identifier or string (as a quoted identifier)
  /// and set \p Res to the identifier contents.
  bool parseIdentifier(StringRef &Res) override;
  void eatToEndOfStatement() override;

  bool checkForValidSection() override;

  /// }

private:
  bool isAltmacroString(SMLoc &StrLoc, SMLoc &EndLoc);
  void altMacroString(StringRef AltMacroStr, std::string &Res);
  bool parseStatement(ParseStatementInfo &Info,
                      MCAsmParserSemaCallback *SI);
  bool parseCurlyBlockScope(SmallVectorImpl<AsmRewrite>& AsmStrRewrites);
  bool parseCppHashLineFilenameComment(SMLoc L);

  void checkForBadMacro(SMLoc DirectiveLoc, StringRef Name, StringRef Body,
                        ArrayRef<MCAsmMacroParameter> Parameters);
  bool expandMacro(raw_svector_ostream &OS, StringRef Body,
                   ArrayRef<MCAsmMacroParameter> Parameters,
                   ArrayRef<MCAsmMacroArgument> A, bool EnableAtPseudoVariable,
                   SMLoc L);

  /// Are macros enabled in the parser?
  bool areMacrosEnabled() {return MacrosEnabledFlag;}

  /// Control a flag in the parser that enables or disables macros.
  void setMacrosEnabled(bool Flag) {MacrosEnabledFlag = Flag;}

  /// Are we inside a macro instantiation?
  bool isInsideMacroInstantiation() {return !ActiveMacros.empty();}

  /// Handle entry to macro instantiation.
  ///
  /// \param M The macro.
  /// \param NameLoc Instantiation location.
  bool handleMacroEntry(const MCAsmMacro *M, SMLoc NameLoc);

  /// Handle exit from macro instantiation.
  void handleMacroExit();

  /// Extract AsmTokens for a macro argument.
  bool parseMacroArgument(MCAsmMacroArgument &MA, bool Vararg);

  /// Parse all macro arguments for a given macro.
  bool parseMacroArguments(const MCAsmMacro *M, MCAsmMacroArguments &A);

  void printMacroInstantiations();
  void printMessage(SMLoc Loc, SourceMgr::DiagKind Kind, const Twine &Msg,
                    SMRange Range = None) const {
    ArrayRef<SMRange> Ranges(Range);
    SrcMgr.PrintMessage(Loc, Kind, Msg, Ranges);
  }
  static void DiagHandler(const SMDiagnostic &Diag, void *Context);

  /// Should we emit DWARF describing this assembler source?  (Returns false if
  /// the source has .file directives, which means we don't want to generate
  /// info describing the assembler source itself.)
  bool enabledGenDwarfForAssembly();

  /// Enter the specified file. This returns true on failure.
  bool enterIncludeFile(const std::string &Filename);

  /// Process the specified file for the .incbin directive.
  /// This returns true on failure.
  bool processIncbinFile(const std::string &Filename, int64_t Skip = 0,
                         const MCExpr *Count = nullptr, SMLoc Loc = SMLoc());

  /// Reset the current lexer position to that given by \p Loc. The
  /// current token is not set; clients should ensure Lex() is called
  /// subsequently.
  ///
  /// \param InBuffer If not 0, should be the known buffer id that contains the
  /// location.
  void jumpToLoc(SMLoc Loc, unsigned InBuffer = 0);

  /// Parse up to the end of statement and a return the contents from the
  /// current token until the end of the statement; the current token on exit
  /// will be either the EndOfStatement or EOF.
  StringRef parseStringToEndOfStatement() override;

  /// Parse until the end of a statement or a comma is encountered,
  /// return the contents from the current token up to the end or comma.
  StringRef parseStringToComma();

  bool parseAssignment(StringRef Name, bool allow_redef,
                       bool NoDeadStrip = false);

  unsigned getBinOpPrecedence(AsmToken::TokenKind K,
                              MCBinaryExpr::Opcode &Kind);

  bool parseBinOpRHS(unsigned Precedence, const MCExpr *&Res, SMLoc &EndLoc);
  bool parseParenExpr(const MCExpr *&Res, SMLoc &EndLoc);
  bool parseBracketExpr(const MCExpr *&Res, SMLoc &EndLoc);

  bool parseRegisterOrRegisterNumber(int64_t &Register, SMLoc DirectiveLoc);

  bool parseCVFunctionId(int64_t &FunctionId, StringRef DirectiveName);
  bool parseCVFileId(int64_t &FileId, StringRef DirectiveName);

  // Generic (target and platform independent) directive parsing.
  enum DirectiveKind {
    DK_NO_DIRECTIVE, // Placeholder
    DK_SET,
    DK_EQU,
    DK_EQUIV,
    DK_ASCII,
    DK_ASCIZ,
    DK_STRING,
    DK_BYTE,
    DK_SHORT,
    DK_RELOC,
    DK_VALUE,
    DK_2BYTE,
    DK_LONG,
    DK_INT,
    DK_4BYTE,
    DK_QUAD,
    DK_8BYTE,
    DK_OCTA,
    DK_DC,
    DK_DC_A,
    DK_DC_B,
    DK_DC_D,
    DK_DC_L,
    DK_DC_S,
    DK_DC_W,
    DK_DC_X,
    DK_DCB,
    DK_DCB_B,
    DK_DCB_D,
    DK_DCB_L,
    DK_DCB_S,
    DK_DCB_W,
    DK_DCB_X,
    DK_DS,
    DK_DS_B,
    DK_DS_D,
    DK_DS_L,
    DK_DS_P,
    DK_DS_S,
    DK_DS_W,
    DK_DS_X,
    DK_SINGLE,
    DK_FLOAT,
    DK_DOUBLE,
    DK_ALIGN,
    DK_ALIGN32,
    DK_BALIGN,
    DK_BALIGNW,
    DK_BALIGNL,
    DK_P2ALIGN,
    DK_P2ALIGNW,
    DK_P2ALIGNL,
    DK_ORG,
    DK_FILL,
    DK_ENDR,
    DK_BUNDLE_ALIGN_MODE,
    DK_BUNDLE_LOCK,
    DK_BUNDLE_UNLOCK,
    DK_ZERO,
    DK_EXTERN,
    DK_GLOBL,
    DK_GLOBAL,
    DK_LAZY_REFERENCE,
    DK_NO_DEAD_STRIP,
    DK_SYMBOL_RESOLVER,
    DK_PRIVATE_EXTERN,
    DK_REFERENCE,
    DK_WEAK_DEFINITION,
    DK_WEAK_REFERENCE,
    DK_WEAK_DEF_CAN_BE_HIDDEN,
    DK_COMM,
    DK_COMMON,
    DK_LCOMM,
    DK_ABORT,
    DK_INCLUDE,
    DK_INCBIN,
    DK_CODE16,
    DK_CODE16GCC,
    DK_REPT,
    DK_IRP,
    DK_IRPC,
    DK_IF,
    DK_IFEQ,
    DK_IFGE,
    DK_IFGT,
    DK_IFLE,
    DK_IFLT,
    DK_IFNE,
    DK_IFB,
    DK_IFNB,
    DK_IFC,
    DK_IFEQS,
    DK_IFNC,
    DK_IFNES,
    DK_IFDEF,
    DK_IFNDEF,
    DK_IFNOTDEF,
    DK_ELSEIF,
    DK_ELSE,
    DK_ENDIF,
    DK_SPACE,
    DK_SKIP,
    DK_FILE,
    DK_LINE,
    DK_LOC,
    DK_STABS,
    DK_CV_FILE,
    DK_CV_FUNC_ID,
    DK_CV_INLINE_SITE_ID,
    DK_CV_LOC,
    DK_CV_LINETABLE,
    DK_CV_INLINE_LINETABLE,
    DK_CV_DEF_RANGE,
    DK_CV_STRINGTABLE,
    DK_CV_FILECHECKSUMS,
    DK_CV_FILECHECKSUM_OFFSET,
    DK_CV_FPO_DATA,
    DK_CFI_SECTIONS,
    DK_CFI_STARTPROC,
    DK_CFI_ENDPROC,
    DK_CFI_DEF_CFA,
    DK_CFI_DEF_CFA_OFFSET,
    DK_CFI_ADJUST_CFA_OFFSET,
    DK_CFI_DEF_CFA_REGISTER,
    DK_CFI_OFFSET,
    DK_CFI_REL_OFFSET,
    DK_CFI_PERSONALITY,
    DK_CFI_LSDA,
    DK_CFI_REMEMBER_STATE,
    DK_CFI_RESTORE_STATE,
    DK_CFI_SAME_VALUE,
    DK_CFI_RESTORE,
    DK_CFI_ESCAPE,
    DK_CFI_RETURN_COLUMN,
    DK_CFI_SIGNAL_FRAME,
    DK_CFI_UNDEFINED,
    DK_CFI_REGISTER,
    DK_CFI_WINDOW_SAVE,
    DK_MACROS_ON,
    DK_MACROS_OFF,
    DK_ALTMACRO,
    DK_NOALTMACRO,
    DK_MACRO,
    DK_EXITM,
    DK_ENDM,
    DK_ENDMACRO,
    DK_PURGEM,
    DK_SLEB128,
    DK_ULEB128,
    DK_ERR,
    DK_ERROR,
    DK_WARNING,
    DK_PRINT,
    DK_ADDRSIG,
    DK_ADDRSIG_SYM,
    DK_END
  };

  /// Maps directive name --> DirectiveKind enum, for
  /// directives parsed by this class.
  StringMap<DirectiveKind> DirectiveKindMap;

  // ".ascii", ".asciz", ".string"
  bool parseDirectiveAscii(StringRef IDVal, bool ZeroTerminated);
  bool parseDirectiveReloc(SMLoc DirectiveLoc); // ".reloc"
  bool parseDirectiveValue(StringRef IDVal,
                           unsigned Size);       // ".byte", ".long", ...
  bool parseDirectiveOctaValue(StringRef IDVal); // ".octa", ...
  bool parseDirectiveRealValue(StringRef IDVal,
                               const fltSemantics &); // ".single", ...
  bool parseDirectiveFill(); // ".fill"
  bool parseDirectiveZero(); // ".zero"
  // ".set", ".equ", ".equiv"
  bool parseDirectiveSet(StringRef IDVal, bool allow_redef);
  bool parseDirectiveOrg(); // ".org"
  // ".align{,32}", ".p2align{,w,l}"
  bool parseDirectiveAlign(bool IsPow2, unsigned ValueSize);

  // ".file", ".line", ".loc", ".stabs"
  bool parseDirectiveFile(SMLoc DirectiveLoc);
  bool parseDirectiveLine();
  bool parseDirectiveLoc();
  bool parseDirectiveStabs();

  // ".cv_file", ".cv_func_id", ".cv_inline_site_id", ".cv_loc", ".cv_linetable",
  // ".cv_inline_linetable", ".cv_def_range"
  bool parseDirectiveCVFile();
  bool parseDirectiveCVFuncId();
  bool parseDirectiveCVInlineSiteId();
  bool parseDirectiveCVLoc();
  bool parseDirectiveCVLinetable();
  bool parseDirectiveCVInlineLinetable();
  bool parseDirectiveCVDefRange();
  bool parseDirectiveCVStringTable();
  bool parseDirectiveCVFileChecksums();
  bool parseDirectiveCVFileChecksumOffset();
  bool parseDirectiveCVFPOData();

  // .cfi directives
  bool parseDirectiveCFIRegister(SMLoc DirectiveLoc);
  bool parseDirectiveCFIWindowSave();
  bool parseDirectiveCFISections();
  bool parseDirectiveCFIStartProc();
  bool parseDirectiveCFIEndProc();
  bool parseDirectiveCFIDefCfaOffset();
  bool parseDirectiveCFIDefCfa(SMLoc DirectiveLoc);
  bool parseDirectiveCFIAdjustCfaOffset();
  bool parseDirectiveCFIDefCfaRegister(SMLoc DirectiveLoc);
  bool parseDirectiveCFIOffset(SMLoc DirectiveLoc);
  bool parseDirectiveCFIRelOffset(SMLoc DirectiveLoc);
  bool parseDirectiveCFIPersonalityOrLsda(bool IsPersonality);
  bool parseDirectiveCFIRememberState();
  bool parseDirectiveCFIRestoreState();
  bool parseDirectiveCFISameValue(SMLoc DirectiveLoc);
  bool parseDirectiveCFIRestore(SMLoc DirectiveLoc);
  bool parseDirectiveCFIEscape();
  bool parseDirectiveCFIReturnColumn(SMLoc DirectiveLoc);
  bool parseDirectiveCFISignalFrame();
  bool parseDirectiveCFIUndefined(SMLoc DirectiveLoc);

  // macro directives
  bool parseDirectivePurgeMacro(SMLoc DirectiveLoc);
  bool parseDirectiveExitMacro(StringRef Directive);
  bool parseDirectiveEndMacro(StringRef Directive);
  bool parseDirectiveMacro(SMLoc DirectiveLoc);
  bool parseDirectiveMacrosOnOff(StringRef Directive);
  // alternate macro mode directives
  bool parseDirectiveAltmacro(StringRef Directive);
  // ".bundle_align_mode"
  bool parseDirectiveBundleAlignMode();
  // ".bundle_lock"
  bool parseDirectiveBundleLock();
  // ".bundle_unlock"
  bool parseDirectiveBundleUnlock();

  // ".space", ".skip"
  bool parseDirectiveSpace(StringRef IDVal);

  // ".dcb"
  bool parseDirectiveDCB(StringRef IDVal, unsigned Size);
  bool parseDirectiveRealDCB(StringRef IDVal, const fltSemantics &);
  // ".ds"
  bool parseDirectiveDS(StringRef IDVal, unsigned Size);

  // .sleb128 (Signed=true) and .uleb128 (Signed=false)
  bool parseDirectiveLEB128(bool Signed);

  /// Parse a directive like ".globl" which
  /// accepts a single symbol (which should be a label or an external).
  bool parseDirectiveSymbolAttribute(MCSymbolAttr Attr);

  bool parseDirectiveComm(bool IsLocal); // ".comm" and ".lcomm"

  bool parseDirectiveAbort(); // ".abort"
  bool parseDirectiveInclude(); // ".include"
  bool parseDirectiveIncbin(); // ".incbin"

  // ".if", ".ifeq", ".ifge", ".ifgt" , ".ifle", ".iflt" or ".ifne"
  bool parseDirectiveIf(SMLoc DirectiveLoc, DirectiveKind DirKind);
  // ".ifb" or ".ifnb", depending on ExpectBlank.
  bool parseDirectiveIfb(SMLoc DirectiveLoc, bool ExpectBlank);
  // ".ifc" or ".ifnc", depending on ExpectEqual.
  bool parseDirectiveIfc(SMLoc DirectiveLoc, bool ExpectEqual);
  // ".ifeqs" or ".ifnes", depending on ExpectEqual.
  bool parseDirectiveIfeqs(SMLoc DirectiveLoc, bool ExpectEqual);
  // ".ifdef" or ".ifndef", depending on expect_defined
  bool parseDirectiveIfdef(SMLoc DirectiveLoc, bool expect_defined);
  bool parseDirectiveElseIf(SMLoc DirectiveLoc); // ".elseif"
  bool parseDirectiveElse(SMLoc DirectiveLoc); // ".else"
  bool parseDirectiveEndIf(SMLoc DirectiveLoc); // .endif
  bool parseEscapedString(std::string &Data) override;

  const MCExpr *applyModifierToExpr(const MCExpr *E,
                                    MCSymbolRefExpr::VariantKind Variant);

  // Macro-like directives
  MCAsmMacro *parseMacroLikeBody(SMLoc DirectiveLoc);
  void instantiateMacroLikeBody(MCAsmMacro *M, SMLoc DirectiveLoc,
                                raw_svector_ostream &OS);
  bool parseDirectiveRept(SMLoc DirectiveLoc, StringRef Directive);
  bool parseDirectiveIrp(SMLoc DirectiveLoc);  // ".irp"
  bool parseDirectiveIrpc(SMLoc DirectiveLoc); // ".irpc"
  bool parseDirectiveEndr(SMLoc DirectiveLoc); // ".endr"

  // "_emit" or "__emit"
  bool parseDirectiveMSEmit(SMLoc DirectiveLoc, ParseStatementInfo &Info,
                            size_t Len);

  // "align"
  bool parseDirectiveMSAlign(SMLoc DirectiveLoc, ParseStatementInfo &Info);

  // "end"
  bool parseDirectiveEnd(SMLoc DirectiveLoc);

  // ".err" or ".error"
  bool parseDirectiveError(SMLoc DirectiveLoc, bool WithMessage);

  // ".warning"
  bool parseDirectiveWarning(SMLoc DirectiveLoc);

  // .print <double-quotes-string>
  bool parseDirectivePrint(SMLoc DirectiveLoc);

  // Directives to support address-significance tables.
  bool parseDirectiveAddrsig();
  bool parseDirectiveAddrsigSym();

  void initializeDirectiveKindMap();
};

} // end anonymous namespace

namespace llvm {

extern MCAsmParserExtension *createDarwinAsmParser();
extern MCAsmParserExtension *createELFAsmParser();
extern MCAsmParserExtension *createCOFFAsmParser();

} // end namespace llvm

enum { DEFAULT_ADDRSPACE = 0 };

AsmParser::AsmParser(SourceMgr &SM, MCContext &Ctx, MCStreamer &Out,
                     const MCAsmInfo &MAI, unsigned CB = 0)
    : Lexer(MAI), Ctx(Ctx), Out(Out), MAI(MAI), SrcMgr(SM),
      CurBuffer(CB ? CB : SM.getMainFileID()), MacrosEnabledFlag(true) {
  HadError = false;
  // Save the old handler.
  SavedDiagHandler = SrcMgr.getDiagHandler();
  SavedDiagContext = SrcMgr.getDiagContext();
  // Set our own handler which calls the saved handler.
  SrcMgr.setDiagHandler(DiagHandler, this);
  Lexer.setBuffer(SrcMgr.getMemoryBuffer(CurBuffer)->getBuffer());

  // Initialize the platform / file format parser.
  switch (Ctx.getObjectFileInfo()->getObjectFileType()) {
  case MCObjectFileInfo::IsCOFF:
    PlatformParser.reset(createCOFFAsmParser());
    break;
  case MCObjectFileInfo::IsMachO:
    PlatformParser.reset(createDarwinAsmParser());
    IsDarwin = true;
    break;
  case MCObjectFileInfo::IsELF:
    PlatformParser.reset(createELFAsmParser());
    break;
  case MCObjectFileInfo::IsWasm:
    // TODO: WASM will need its own MCAsmParserExtension implementation, but
    // for now we can re-use the ELF one, since the directives can be the
    // same for now.
    PlatformParser.reset(createELFAsmParser());
    break;
  }

  PlatformParser->Initialize(*this);
  initializeDirectiveKindMap();

  NumOfMacroInstantiations = 0;
}

AsmParser::~AsmParser() {
  assert((HadError || ActiveMacros.empty()) &&
         "Unexpected active macro instantiation!");

  // Restore the saved diagnostics handler and context for use during
  // finalization.
  SrcMgr.setDiagHandler(SavedDiagHandler, SavedDiagContext);
}

void AsmParser::printMacroInstantiations() {
  // Print the active macro instantiation stack.
  for (std::vector<MacroInstantiation *>::const_reverse_iterator
           it = ActiveMacros.rbegin(),
           ie = ActiveMacros.rend();
       it != ie; ++it)
    printMessage((*it)->InstantiationLoc, SourceMgr::DK_Note,
                 "while in macro instantiation");
}

void AsmParser::Note(SMLoc L, const Twine &Msg, SMRange Range) {
  printPendingErrors();
  printMessage(L, SourceMgr::DK_Note, Msg, Range);
  printMacroInstantiations();
}

bool AsmParser::Warning(SMLoc L, const Twine &Msg, SMRange Range) {
  if(getTargetParser().getTargetOptions().MCNoWarn)
    return false;
  if (getTargetParser().getTargetOptions().MCFatalWarnings)
    return Error(L, Msg, Range);
  printMessage(L, SourceMgr::DK_Warning, Msg, Range);
  printMacroInstantiations();
  return false;
}

bool AsmParser::printError(SMLoc L, const Twine &Msg, SMRange Range) {
  HadError = true;
  printMessage(L, SourceMgr::DK_Error, Msg, Range);
  printMacroInstantiations();
  return true;
}

bool AsmParser::enterIncludeFile(const std::string &Filename) {
  std::string IncludedFile;
  unsigned NewBuf =
      SrcMgr.AddIncludeFile(Filename, Lexer.getLoc(), IncludedFile);
  if (!NewBuf)
    return true;

  CurBuffer = NewBuf;
  Lexer.setBuffer(SrcMgr.getMemoryBuffer(CurBuffer)->getBuffer());
  return false;
}

/// Process the specified .incbin file by searching for it in the include paths
/// then just emitting the byte contents of the file to the streamer. This
/// returns true on failure.
bool AsmParser::processIncbinFile(const std::string &Filename, int64_t Skip,
                                  const MCExpr *Count, SMLoc Loc) {
  std::string IncludedFile;
  unsigned NewBuf =
      SrcMgr.AddIncludeFile(Filename, Lexer.getLoc(), IncludedFile);
  if (!NewBuf)
    return true;

  // Pick up the bytes from the file and emit them.
  StringRef Bytes = SrcMgr.getMemoryBuffer(NewBuf)->getBuffer();
  Bytes = Bytes.drop_front(Skip);
  if (Count) {
    int64_t Res;
    if (!Count->evaluateAsAbsolute(Res, getStreamer().getAssemblerPtr()))
      return Error(Loc, "expected absolute expression");
    if (Res < 0)
      return Warning(Loc, "negative count has no effect");
    Bytes = Bytes.take_front(Res);
  }
  getStreamer().EmitBytes(Bytes);
  return false;
}

void AsmParser::jumpToLoc(SMLoc Loc, unsigned InBuffer) {
  CurBuffer = InBuffer ? InBuffer : SrcMgr.FindBufferContainingLoc(Loc);
  Lexer.setBuffer(SrcMgr.getMemoryBuffer(CurBuffer)->getBuffer(),
                  Loc.getPointer());
}

const AsmToken &AsmParser::Lex() {
  if (Lexer.getTok().is(AsmToken::Error))
    Error(Lexer.getErrLoc(), Lexer.getErr());

  // if it's a end of statement with a comment in it
  if (getTok().is(AsmToken::EndOfStatement)) {
    // if this is a line comment output it.
    if (!getTok().getString().empty() && getTok().getString().front() != '\n' &&
        getTok().getString().front() != '\r' && MAI.preserveAsmComments())
      Out.addExplicitComment(Twine(getTok().getString()));
  }

  const AsmToken *tok = &Lexer.Lex();

  // Parse comments here to be deferred until end of next statement.
  while (tok->is(AsmToken::Comment)) {
    if (MAI.preserveAsmComments())
      Out.addExplicitComment(Twine(tok->getString()));
    tok = &Lexer.Lex();
  }

  if (tok->is(AsmToken::Eof)) {
    // If this is the end of an included file, pop the parent file off the
    // include stack.
    SMLoc ParentIncludeLoc = SrcMgr.getParentIncludeLoc(CurBuffer);
    if (ParentIncludeLoc != SMLoc()) {
      jumpToLoc(ParentIncludeLoc);
      return Lex();
    }
  }

  return *tok;
}

bool AsmParser::enabledGenDwarfForAssembly() {
  // Check whether the user specified -g.
  if (!getContext().getGenDwarfForAssembly())
    return false;
  // If we haven't encountered any .file directives (which would imply that
  // the assembler source was produced with debug info already) then emit one
  // describing the assembler source file itself.
  if (getContext().getGenDwarfFileNumber() == 0)
    getContext().setGenDwarfFileNumber(getStreamer().EmitDwarfFileDirective(
        0, StringRef(), getContext().getMainFileName()));
  return true;
}

bool AsmParser::Run(bool NoInitialTextSection, bool NoFinalize) {
  // Create the initial section, if requested.
  if (!NoInitialTextSection)
    Out.InitSections(false);

  // Prime the lexer.
  Lex();

  HadError = false;
  AsmCond StartingCondState = TheCondState;
  SmallVector<AsmRewrite, 4> AsmStrRewrites;

  // If we are generating dwarf for assembly source files save the initial text
  // section.  (Don't use enabledGenDwarfForAssembly() here, as we aren't
  // emitting any actual debug info yet and haven't had a chance to parse any
  // embedded .file directives.)
  if (getContext().getGenDwarfForAssembly()) {
    MCSection *Sec = getStreamer().getCurrentSectionOnly();
    if (!Sec->getBeginSymbol()) {
      MCSymbol *SectionStartSym = getContext().createTempSymbol();
      getStreamer().EmitLabel(SectionStartSym);
      Sec->setBeginSymbol(SectionStartSym);
    }
    bool InsertResult = getContext().addGenDwarfSection(Sec);
    assert(InsertResult && ".text section should not have debug info yet");
    (void)InsertResult;
  }

  // While we have input, parse each statement.
  while (Lexer.isNot(AsmToken::Eof)) {
    ParseStatementInfo Info(&AsmStrRewrites);
    if (!parseStatement(Info, nullptr))
      continue;

    // If we have a Lexer Error we are on an Error Token. Load in Lexer Error
    // for printing ErrMsg via Lex() only if no (presumably better) parser error
    // exists.
    if (!hasPendingError() && Lexer.getTok().is(AsmToken::Error)) {
      Lex();
    }

    // parseStatement returned true so may need to emit an error.
    printPendingErrors();

    // Skipping to the next line if needed.
    if (!getLexer().isAtStartOfStatement())
      eatToEndOfStatement();
  }

  // All errors should have been emitted.
  assert(!hasPendingError() && "unexpected error from parseStatement");

  getTargetParser().flushPendingInstructions(getStreamer());

  if (TheCondState.TheCond != StartingCondState.TheCond ||
      TheCondState.Ignore != StartingCondState.Ignore)
    printError(getTok().getLoc(), "unmatched .ifs or .elses");
  // Check to see there are no empty DwarfFile slots.
  const auto &LineTables = getContext().getMCDwarfLineTables();
  if (!LineTables.empty()) {
    unsigned Index = 0;
    for (const auto &File : LineTables.begin()->second.getMCDwarfFiles()) {
      if (File.Name.empty() && Index != 0)
        printError(getTok().getLoc(), "unassigned file number: " +
                                          Twine(Index) +
                                          " for .file directives");
      ++Index;
    }
  }

  // Check to see that all assembler local symbols were actually defined.
  // Targets that don't do subsections via symbols may not want this, though,
  // so conservatively exclude them. Only do this if we're finalizing, though,
  // as otherwise we won't necessarilly have seen everything yet.
  if (!NoFinalize) {
    if (MAI.hasSubsectionsViaSymbols()) {
      for (const auto &TableEntry : getContext().getSymbols()) {
        MCSymbol *Sym = TableEntry.getValue();
        // Variable symbols may not be marked as defined, so check those
        // explicitly. If we know it's a variable, we have a definition for
        // the purposes of this check.
        if (Sym->isTemporary() && !Sym->isVariable() && !Sym->isDefined())
          // FIXME: We would really like to refer back to where the symbol was
          // first referenced for a source location. We need to add something
          // to track that. Currently, we just point to the end of the file.
          printError(getTok().getLoc(), "assembler local symbol '" +
                                            Sym->getName() + "' not defined");
      }
    }

    // Temporary symbols like the ones for directional jumps don't go in the
    // symbol table. They also need to be diagnosed in all (final) cases.
    for (std::tuple<SMLoc, CppHashInfoTy, MCSymbol *> &LocSym : DirLabels) {
      if (std::get<2>(LocSym)->isUndefined()) {
        // Reset the state of any "# line file" directives we've seen to the
        // context as it was at the diagnostic site.
        CppHashInfo = std::get<1>(LocSym);
        printError(std::get<0>(LocSym), "directional label undefined");
      }
    }
  }

  // Finalize the output stream if there are no errors and if the client wants
  // us to.
  if (!HadError && !NoFinalize)
    Out.Finish();

  return HadError || getContext().hadError();
}

bool AsmParser::checkForValidSection() {
  if (!ParsingInlineAsm && !getStreamer().getCurrentSectionOnly()) {
    Out.InitSections(false);
    return Error(getTok().getLoc(),
                 "expected section directive before assembly directive");
  }
  return false;
}

/// Throw away the rest of the line for testing purposes.
void AsmParser::eatToEndOfStatement() {
  while (Lexer.isNot(AsmToken::EndOfStatement) && Lexer.isNot(AsmToken::Eof))
    Lexer.Lex();

  // Eat EOL.
  if (Lexer.is(AsmToken::EndOfStatement))
    Lexer.Lex();
}

StringRef AsmParser::parseStringToEndOfStatement() {
  const char *Start = getTok().getLoc().getPointer();

  while (Lexer.isNot(AsmToken::EndOfStatement) && Lexer.isNot(AsmToken::Eof))
    Lexer.Lex();

  const char *End = getTok().getLoc().getPointer();
  return StringRef(Start, End - Start);
}

StringRef AsmParser::parseStringToComma() {
  const char *Start = getTok().getLoc().getPointer();

  while (Lexer.isNot(AsmToken::EndOfStatement) &&
         Lexer.isNot(AsmToken::Comma) && Lexer.isNot(AsmToken::Eof))
    Lexer.Lex();

  const char *End = getTok().getLoc().getPointer();
  return StringRef(Start, End - Start);
}

/// Parse a paren expression and return it.
/// NOTE: This assumes the leading '(' has already been consumed.
///
/// parenexpr ::= expr)
///
bool AsmParser::parseParenExpr(const MCExpr *&Res, SMLoc &EndLoc) {
  if (parseExpression(Res))
    return true;
  if (Lexer.isNot(AsmToken::RParen))
    return TokError("expected ')' in parentheses expression");
  EndLoc = Lexer.getTok().getEndLoc();
  Lex();
  return false;
}

/// Parse a bracket expression and return it.
/// NOTE: This assumes the leading '[' has already been consumed.
///
/// bracketexpr ::= expr]
///
bool AsmParser::parseBracketExpr(const MCExpr *&Res, SMLoc &EndLoc) {
  if (parseExpression(Res))
    return true;
  EndLoc = getTok().getEndLoc();
  if (parseToken(AsmToken::RBrac, "expected ']' in brackets expression"))
    return true;
  return false;
}

/// Parse a primary expression and return it.
///  primaryexpr ::= (parenexpr
///  primaryexpr ::= symbol
///  primaryexpr ::= number
///  primaryexpr ::= '.'
///  primaryexpr ::= ~,+,- primaryexpr
bool AsmParser::parsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc) {
  SMLoc FirstTokenLoc = getLexer().getLoc();
  AsmToken::TokenKind FirstTokenKind = Lexer.getKind();
  switch (FirstTokenKind) {
  default:
    return TokError("unknown token in expression");
  // If we have an error assume that we've already handled it.
  case AsmToken::Error:
    return true;
  case AsmToken::Exclaim:
    Lex(); // Eat the operator.
    if (parsePrimaryExpr(Res, EndLoc))
      return true;
    Res = MCUnaryExpr::createLNot(Res, getContext(), FirstTokenLoc);
    return false;
  case AsmToken::Dollar:
  case AsmToken::At:
  case AsmToken::String:
  case AsmToken::Identifier: {
    StringRef Identifier;
    if (parseIdentifier(Identifier)) {
      // We may have failed but $ may be a valid token.
      if (getTok().is(AsmToken::Dollar)) {
        if (Lexer.getMAI().getDollarIsPC()) {
          Lex();
          // This is a '$' reference, which references the current PC.  Emit a
          // temporary label to the streamer and refer to it.
          MCSymbol *Sym = Ctx.createTempSymbol();
          Out.EmitLabel(Sym);
          Res = MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_None,
                                        getContext());
          EndLoc = FirstTokenLoc;
          return false;
        }
        return Error(FirstTokenLoc, "invalid token in expression");
      }
    }
    // Parse symbol variant
    std::pair<StringRef, StringRef> Split;
    if (!MAI.useParensForSymbolVariant()) {
      if (FirstTokenKind == AsmToken::String) {
        if (Lexer.is(AsmToken::At)) {
          Lex(); // eat @
          SMLoc AtLoc = getLexer().getLoc();
          StringRef VName;
          if (parseIdentifier(VName))
            return Error(AtLoc, "expected symbol variant after '@'");

          Split = std::make_pair(Identifier, VName);
        }
      } else {
        Split = Identifier.split('@');
      }
    } else if (Lexer.is(AsmToken::LParen)) {
      Lex(); // eat '('.
      StringRef VName;
      parseIdentifier(VName);
      // eat ')'.
      if (parseToken(AsmToken::RParen,
                     "unexpected token in variant, expected ')'"))
        return true;
      Split = std::make_pair(Identifier, VName);
    }

    EndLoc = SMLoc::getFromPointer(Identifier.end());

    // This is a symbol reference.
    StringRef SymbolName = Identifier;
    if (SymbolName.empty())
      return true;

    MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;

    // Lookup the symbol variant if used.
    if (!Split.second.empty()) {
      Variant = MCSymbolRefExpr::getVariantKindForName(Split.second);
      if (Variant != MCSymbolRefExpr::VK_Invalid) {
        SymbolName = Split.first;
      } else if (MAI.doesAllowAtInName() && !MAI.useParensForSymbolVariant()) {
        Variant = MCSymbolRefExpr::VK_None;
      } else {
        return Error(SMLoc::getFromPointer(Split.second.begin()),
                     "invalid variant '" + Split.second + "'");
      }
    }

    MCSymbol *Sym = getContext().getOrCreateSymbol(SymbolName);

    // If this is an absolute variable reference, substitute it now to preserve
    // semantics in the face of reassignment.
    if (Sym->isVariable()) {
      auto V = Sym->getVariableValue(/*SetUsed*/ false);
      bool DoInline = isa<MCConstantExpr>(V);
      if (auto TV = dyn_cast<MCTargetExpr>(V))
        DoInline = TV->inlineAssignedExpr();
      if (DoInline) {
        if (Variant)
          return Error(EndLoc, "unexpected modifier on variable reference");
        Res = Sym->getVariableValue(/*SetUsed*/ false);
        return false;
      }
    }

    // Otherwise create a symbol ref.
    Res = MCSymbolRefExpr::create(Sym, Variant, getContext(), FirstTokenLoc);
    return false;
  }
  case AsmToken::BigNum:
    return TokError("literal value out of range for directive");
  case AsmToken::Integer: {
    SMLoc Loc = getTok().getLoc();
    int64_t IntVal = getTok().getIntVal();
    Res = MCConstantExpr::create(IntVal, getContext());
    EndLoc = Lexer.getTok().getEndLoc();
    Lex(); // Eat token.
    // Look for 'b' or 'f' following an Integer as a directional label
    if (Lexer.getKind() == AsmToken::Identifier) {
      StringRef IDVal = getTok().getString();
      // Lookup the symbol variant if used.
      std::pair<StringRef, StringRef> Split = IDVal.split('@');
      MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
      if (Split.first.size() != IDVal.size()) {
        Variant = MCSymbolRefExpr::getVariantKindForName(Split.second);
        if (Variant == MCSymbolRefExpr::VK_Invalid)
          return TokError("invalid variant '" + Split.second + "'");
        IDVal = Split.first;
      }
      if (IDVal == "f" || IDVal == "b") {
        MCSymbol *Sym =
            Ctx.getDirectionalLocalSymbol(IntVal, IDVal == "b");
        Res = MCSymbolRefExpr::create(Sym, Variant, getContext());
        if (IDVal == "b" && Sym->isUndefined())
          return Error(Loc, "directional label undefined");
        DirLabels.push_back(std::make_tuple(Loc, CppHashInfo, Sym));
        EndLoc = Lexer.getTok().getEndLoc();
        Lex(); // Eat identifier.
      }
    }
    return false;
  }
  case AsmToken::Real: {
    APFloat RealVal(APFloat::IEEEdouble(), getTok().getString());
    uint64_t IntVal = RealVal.bitcastToAPInt().getZExtValue();
    Res = MCConstantExpr::create(IntVal, getContext());
    EndLoc = Lexer.getTok().getEndLoc();
    Lex(); // Eat token.
    return false;
  }
  case AsmToken::Dot: {
    // This is a '.' reference, which references the current PC.  Emit a
    // temporary label to the streamer and refer to it.
    MCSymbol *Sym = Ctx.createTempSymbol();
    Out.EmitLabel(Sym);
    Res = MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_None, getContext());
    EndLoc = Lexer.getTok().getEndLoc();
    Lex(); // Eat identifier.
    return false;
  }
  case AsmToken::LParen:
    Lex(); // Eat the '('.
    return parseParenExpr(Res, EndLoc);
  case AsmToken::LBrac:
    if (!PlatformParser->HasBracketExpressions())
      return TokError("brackets expression not supported on this target");
    Lex(); // Eat the '['.
    return parseBracketExpr(Res, EndLoc);
  case AsmToken::Minus:
    Lex(); // Eat the operator.
    if (parsePrimaryExpr(Res, EndLoc))
      return true;
    Res = MCUnaryExpr::createMinus(Res, getContext(), FirstTokenLoc);
    return false;
  case AsmToken::Plus:
    Lex(); // Eat the operator.
    if (parsePrimaryExpr(Res, EndLoc))
      return true;
    Res = MCUnaryExpr::createPlus(Res, getContext(), FirstTokenLoc);
    return false;
  case AsmToken::Tilde:
    Lex(); // Eat the operator.
    if (parsePrimaryExpr(Res, EndLoc))
      return true;
    Res = MCUnaryExpr::createNot(Res, getContext(), FirstTokenLoc);
    return false;
  // MIPS unary expression operators. The lexer won't generate these tokens if
  // MCAsmInfo::HasMipsExpressions is false for the target.
  case AsmToken::PercentCall16:
  case AsmToken::PercentCall_Hi:
  case AsmToken::PercentCall_Lo:
  case AsmToken::PercentDtprel_Hi:
  case AsmToken::PercentDtprel_Lo:
  case AsmToken::PercentGot:
  case AsmToken::PercentGot_Disp:
  case AsmToken::PercentGot_Hi:
  case AsmToken::PercentGot_Lo:
  case AsmToken::PercentGot_Ofst:
  case AsmToken::PercentGot_Page:
  case AsmToken::PercentGottprel:
  case AsmToken::PercentGp_Rel:
  case AsmToken::PercentHi:
  case AsmToken::PercentHigher:
  case AsmToken::PercentHighest:
  case AsmToken::PercentLo:
  case AsmToken::PercentNeg:
  case AsmToken::PercentPcrel_Hi:
  case AsmToken::PercentPcrel_Lo:
  case AsmToken::PercentTlsgd:
  case AsmToken::PercentTlsldm:
  case AsmToken::PercentTprel_Hi:
  case AsmToken::PercentTprel_Lo:
    Lex(); // Eat the operator.
    if (Lexer.isNot(AsmToken::LParen))
      return TokError("expected '(' after operator");
    Lex(); // Eat the operator.
    if (parseExpression(Res, EndLoc))
      return true;
    if (Lexer.isNot(AsmToken::RParen))
      return TokError("expected ')'");
    Lex(); // Eat the operator.
    Res = getTargetParser().createTargetUnaryExpr(Res, FirstTokenKind, Ctx);
    return !Res;
  }
}

bool AsmParser::parseExpression(const MCExpr *&Res) {
  SMLoc EndLoc;
  return parseExpression(Res, EndLoc);
}

const MCExpr *
AsmParser::applyModifierToExpr(const MCExpr *E,
                               MCSymbolRefExpr::VariantKind Variant) {
  // Ask the target implementation about this expression first.
  const MCExpr *NewE = getTargetParser().applyModifierToExpr(E, Variant, Ctx);
  if (NewE)
    return NewE;
  // Recurse over the given expression, rebuilding it to apply the given variant
  // if there is exactly one symbol.
  switch (E->getKind()) {
  case MCExpr::Target:
  case MCExpr::Constant:
    return nullptr;

  case MCExpr::SymbolRef: {
    const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(E);

    if (SRE->getKind() != MCSymbolRefExpr::VK_None) {
      TokError("invalid variant on expression '" + getTok().getIdentifier() +
               "' (already modified)");
      return E;
    }

    return MCSymbolRefExpr::create(&SRE->getSymbol(), Variant, getContext());
  }

  case MCExpr::Unary: {
    const MCUnaryExpr *UE = cast<MCUnaryExpr>(E);
    const MCExpr *Sub = applyModifierToExpr(UE->getSubExpr(), Variant);
    if (!Sub)
      return nullptr;
    return MCUnaryExpr::create(UE->getOpcode(), Sub, getContext());
  }

  case MCExpr::Binary: {
    const MCBinaryExpr *BE = cast<MCBinaryExpr>(E);
    const MCExpr *LHS = applyModifierToExpr(BE->getLHS(), Variant);
    const MCExpr *RHS = applyModifierToExpr(BE->getRHS(), Variant);

    if (!LHS && !RHS)
      return nullptr;

    if (!LHS)
      LHS = BE->getLHS();
    if (!RHS)
      RHS = BE->getRHS();

    return MCBinaryExpr::create(BE->getOpcode(), LHS, RHS, getContext());
  }
  }

  llvm_unreachable("Invalid expression kind!");
}

/// This function checks if the next token is <string> type or arithmetic.
/// string that begin with character '<' must end with character '>'.
/// otherwise it is arithmetics.
/// If the function returns a 'true' value,
/// the End argument will be filled with the last location pointed to the '>'
/// character.

/// There is a gap between the AltMacro's documentation and the single quote implementation.
/// GCC does not fully support this feature and so we will not support it.
/// TODO: Adding single quote as a string.
bool AsmParser::isAltmacroString(SMLoc &StrLoc, SMLoc &EndLoc) {
  assert((StrLoc.getPointer() != NULL) &&
         "Argument to the function cannot be a NULL value");
  const char *CharPtr = StrLoc.getPointer();
  while ((*CharPtr != '>') && (*CharPtr != '\n') && (*CharPtr != '\r') &&
         (*CharPtr != '\0')) {
    if (*CharPtr == '!')
      CharPtr++;
    CharPtr++;
  }
  if (*CharPtr == '>') {
    EndLoc = StrLoc.getFromPointer(CharPtr + 1);
    return true;
  }
  return false;
}

/// creating a string without the escape characters '!'.
void AsmParser::altMacroString(StringRef AltMacroStr,std::string &Res) {
  for (size_t Pos = 0; Pos < AltMacroStr.size(); Pos++) {
    if (AltMacroStr[Pos] == '!')
      Pos++;
    Res += AltMacroStr[Pos];
  }
}

/// Parse an expression and return it.
///
///  expr ::= expr &&,|| expr               -> lowest.
///  expr ::= expr |,^,&,! expr
///  expr ::= expr ==,!=,<>,<,<=,>,>= expr
///  expr ::= expr <<,>> expr
///  expr ::= expr +,- expr
///  expr ::= expr *,/,% expr               -> highest.
///  expr ::= primaryexpr
///
bool AsmParser::parseExpression(const MCExpr *&Res, SMLoc &EndLoc) {
  // Parse the expression.
  Res = nullptr;
  if (getTargetParser().parsePrimaryExpr(Res, EndLoc) ||
      parseBinOpRHS(1, Res, EndLoc))
    return true;

  // As a special case, we support 'a op b @ modifier' by rewriting the
  // expression to include the modifier. This is inefficient, but in general we
  // expect users to use 'a@modifier op b'.
  if (Lexer.getKind() == AsmToken::At) {
    Lex();

    if (Lexer.isNot(AsmToken::Identifier))
      return TokError("unexpected symbol modifier following '@'");

    MCSymbolRefExpr::VariantKind Variant =
        MCSymbolRefExpr::getVariantKindForName(getTok().getIdentifier());
    if (Variant == MCSymbolRefExpr::VK_Invalid)
      return TokError("invalid variant '" + getTok().getIdentifier() + "'");

    const MCExpr *ModifiedRes = applyModifierToExpr(Res, Variant);
    if (!ModifiedRes) {
      return TokError("invalid modifier '" + getTok().getIdentifier() +
                      "' (no symbols present)");
    }

    Res = ModifiedRes;
    Lex();
  }

  // Try to constant fold it up front, if possible. Do not exploit
  // assembler here.
  int64_t Value;
  if (Res->evaluateAsAbsolute(Value))
    Res = MCConstantExpr::create(Value, getContext());

  return false;
}

bool AsmParser::parseParenExpression(const MCExpr *&Res, SMLoc &EndLoc) {
  Res = nullptr;
  return parseParenExpr(Res, EndLoc) || parseBinOpRHS(1, Res, EndLoc);
}

bool AsmParser::parseParenExprOfDepth(unsigned ParenDepth, const MCExpr *&Res,
                                      SMLoc &EndLoc) {
  if (parseParenExpr(Res, EndLoc))
    return true;

  for (; ParenDepth > 0; --ParenDepth) {
    if (parseBinOpRHS(1, Res, EndLoc))
      return true;

    // We don't Lex() the last RParen.
    // This is the same behavior as parseParenExpression().
    if (ParenDepth - 1 > 0) {
      EndLoc = getTok().getEndLoc();
      if (parseToken(AsmToken::RParen,
                     "expected ')' in parentheses expression"))
        return true;
    }
  }
  return false;
}

bool AsmParser::parseAbsoluteExpression(int64_t &Res) {
  const MCExpr *Expr;

  SMLoc StartLoc = Lexer.getLoc();
  if (parseExpression(Expr))
    return true;

  if (!Expr->evaluateAsAbsolute(Res, getStreamer().getAssemblerPtr()))
    return Error(StartLoc, "expected absolute expression");

  return false;
}

static unsigned getDarwinBinOpPrecedence(AsmToken::TokenKind K,
                                         MCBinaryExpr::Opcode &Kind,
                                         bool ShouldUseLogicalShr) {
  switch (K) {
  default:
    return 0; // not a binop.

  // Lowest Precedence: &&, ||
  case AsmToken::AmpAmp:
    Kind = MCBinaryExpr::LAnd;
    return 1;
  case AsmToken::PipePipe:
    Kind = MCBinaryExpr::LOr;
    return 1;

  // Low Precedence: |, &, ^
  //
  // FIXME: gas seems to support '!' as an infix operator?
  case AsmToken::Pipe:
    Kind = MCBinaryExpr::Or;
    return 2;
  case AsmToken::Caret:
    Kind = MCBinaryExpr::Xor;
    return 2;
  case AsmToken::Amp:
    Kind = MCBinaryExpr::And;
    return 2;

  // Low Intermediate Precedence: ==, !=, <>, <, <=, >, >=
  case AsmToken::EqualEqual:
    Kind = MCBinaryExpr::EQ;
    return 3;
  case AsmToken::ExclaimEqual:
  case AsmToken::LessGreater:
    Kind = MCBinaryExpr::NE;
    return 3;
  case AsmToken::Less:
    Kind = MCBinaryExpr::LT;
    return 3;
  case AsmToken::LessEqual:
    Kind = MCBinaryExpr::LTE;
    return 3;
  case AsmToken::Greater:
    Kind = MCBinaryExpr::GT;
    return 3;
  case AsmToken::GreaterEqual:
    Kind = MCBinaryExpr::GTE;
    return 3;

  // Intermediate Precedence: <<, >>
  case AsmToken::LessLess:
    Kind = MCBinaryExpr::Shl;
    return 4;
  case AsmToken::GreaterGreater:
    Kind = ShouldUseLogicalShr ? MCBinaryExpr::LShr : MCBinaryExpr::AShr;
    return 4;

  // High Intermediate Precedence: +, -
  case AsmToken::Plus:
    Kind = MCBinaryExpr::Add;
    return 5;
  case AsmToken::Minus:
    Kind = MCBinaryExpr::Sub;
    return 5;

  // Highest Precedence: *, /, %
  case AsmToken::Star:
    Kind = MCBinaryExpr::Mul;
    return 6;
  case AsmToken::Slash:
    Kind = MCBinaryExpr::Div;
    return 6;
  case AsmToken::Percent:
    Kind = MCBinaryExpr::Mod;
    return 6;
  }
}

static unsigned getGNUBinOpPrecedence(AsmToken::TokenKind K,
                                      MCBinaryExpr::Opcode &Kind,
                                      bool ShouldUseLogicalShr) {
  switch (K) {
  default:
    return 0; // not a binop.

  // Lowest Precedence: &&, ||
  case AsmToken::AmpAmp:
    Kind = MCBinaryExpr::LAnd;
    return 2;
  case AsmToken::PipePipe:
    Kind = MCBinaryExpr::LOr;
    return 1;

  // Low Precedence: ==, !=, <>, <, <=, >, >=
  case AsmToken::EqualEqual:
    Kind = MCBinaryExpr::EQ;
    return 3;
  case AsmToken::ExclaimEqual:
  case AsmToken::LessGreater:
    Kind = MCBinaryExpr::NE;
    return 3;
  case AsmToken::Less:
    Kind = MCBinaryExpr::LT;
    return 3;
  case AsmToken::LessEqual:
    Kind = MCBinaryExpr::LTE;
    return 3;
  case AsmToken::Greater:
    Kind = MCBinaryExpr::GT;
    return 3;
  case AsmToken::GreaterEqual:
    Kind = MCBinaryExpr::GTE;
    return 3;

  // Low Intermediate Precedence: +, -
  case AsmToken::Plus:
    Kind = MCBinaryExpr::Add;
    return 4;
  case AsmToken::Minus:
    Kind = MCBinaryExpr::Sub;
    return 4;

  // High Intermediate Precedence: |, &, ^
  //
  // FIXME: gas seems to support '!' as an infix operator?
  case AsmToken::Pipe:
    Kind = MCBinaryExpr::Or;
    return 5;
  case AsmToken::Caret:
    Kind = MCBinaryExpr::Xor;
    return 5;
  case AsmToken::Amp:
    Kind = MCBinaryExpr::And;
    return 5;

  // Highest Precedence: *, /, %, <<, >>
  case AsmToken::Star:
    Kind = MCBinaryExpr::Mul;
    return 6;
  case AsmToken::Slash:
    Kind = MCBinaryExpr::Div;
    return 6;
  case AsmToken::Percent:
    Kind = MCBinaryExpr::Mod;
    return 6;
  case AsmToken::LessLess:
    Kind = MCBinaryExpr::Shl;
    return 6;
  case AsmToken::GreaterGreater:
    Kind = ShouldUseLogicalShr ? MCBinaryExpr::LShr : MCBinaryExpr::AShr;
    return 6;
  }
}

unsigned AsmParser::getBinOpPrecedence(AsmToken::TokenKind K,
                                       MCBinaryExpr::Opcode &Kind) {
  bool ShouldUseLogicalShr = MAI.shouldUseLogicalShr();
  return IsDarwin ? getDarwinBinOpPrecedence(K, Kind, ShouldUseLogicalShr)
                  : getGNUBinOpPrecedence(K, Kind, ShouldUseLogicalShr);
}

/// Parse all binary operators with precedence >= 'Precedence'.
/// Res contains the LHS of the expression on input.
bool AsmParser::parseBinOpRHS(unsigned Precedence, const MCExpr *&Res,
                              SMLoc &EndLoc) {
  SMLoc StartLoc = Lexer.getLoc();
  while (true) {
    MCBinaryExpr::Opcode Kind = MCBinaryExpr::Add;
    unsigned TokPrec = getBinOpPrecedence(Lexer.getKind(), Kind);

    // If the next token is lower precedence than we are allowed to eat, return
    // successfully with what we ate already.
    if (TokPrec < Precedence)
      return false;

    Lex();

    // Eat the next primary expression.
    const MCExpr *RHS;
    if (getTargetParser().parsePrimaryExpr(RHS, EndLoc))
      return true;

    // If BinOp binds less tightly with RHS than the operator after RHS, let
    // the pending operator take RHS as its LHS.
    MCBinaryExpr::Opcode Dummy;
    unsigned NextTokPrec = getBinOpPrecedence(Lexer.getKind(), Dummy);
    if (TokPrec < NextTokPrec && parseBinOpRHS(TokPrec + 1, RHS, EndLoc))
      return true;

    // Merge LHS and RHS according to operator.
    Res = MCBinaryExpr::create(Kind, Res, RHS, getContext(), StartLoc);
  }
}

/// ParseStatement:
///   ::= EndOfStatement
///   ::= Label* Directive ...Operands... EndOfStatement
///   ::= Label* Identifier OperandList* EndOfStatement
bool AsmParser::parseStatement(ParseStatementInfo &Info,
                               MCAsmParserSemaCallback *SI) {
  assert(!hasPendingError() && "parseStatement started with pending error");
  // Eat initial spaces and comments
  while (Lexer.is(AsmToken::Space))
    Lex();
  if (Lexer.is(AsmToken::EndOfStatement)) {
    // if this is a line comment we can drop it safely
    if (getTok().getString().empty() || getTok().getString().front() == '\r' ||
        getTok().getString().front() == '\n')
      Out.AddBlankLine();
    Lex();
    return false;
  }
  // Statements always start with an identifier.
  AsmToken ID = getTok();
  SMLoc IDLoc = ID.getLoc();
  StringRef IDVal;
  int64_t LocalLabelVal = -1;
  if (Lexer.is(AsmToken::HashDirective))
    return parseCppHashLineFilenameComment(IDLoc);
  // Allow an integer followed by a ':' as a directional local label.
  if (Lexer.is(AsmToken::Integer)) {
    LocalLabelVal = getTok().getIntVal();
    if (LocalLabelVal < 0) {
      if (!TheCondState.Ignore) {
        Lex(); // always eat a token
        return Error(IDLoc, "unexpected token at start of statement");
      }
      IDVal = "";
    } else {
      IDVal = getTok().getString();
      Lex(); // Consume the integer token to be used as an identifier token.
      if (Lexer.getKind() != AsmToken::Colon) {
        if (!TheCondState.Ignore) {
          Lex(); // always eat a token
          return Error(IDLoc, "unexpected token at start of statement");
        }
      }
    }
  } else if (Lexer.is(AsmToken::Dot)) {
    // Treat '.' as a valid identifier in this context.
    Lex();
    IDVal = ".";
  } else if (Lexer.is(AsmToken::LCurly)) {
    // Treat '{' as a valid identifier in this context.
    Lex();
    IDVal = "{";

  } else if (Lexer.is(AsmToken::RCurly)) {
    // Treat '}' as a valid identifier in this context.
    Lex();
    IDVal = "}";
  } else if (Lexer.is(AsmToken::Star) &&
             getTargetParser().starIsStartOfStatement()) {
    // Accept '*' as a valid start of statement.
    Lex();
    IDVal = "*";
  } else if (parseIdentifier(IDVal)) {
    if (!TheCondState.Ignore) {
      Lex(); // always eat a token
      return Error(IDLoc, "unexpected token at start of statement");
    }
    IDVal = "";
  }

  // Handle conditional assembly here before checking for skipping.  We
  // have to do this so that .endif isn't skipped in a ".if 0" block for
  // example.
  StringMap<DirectiveKind>::const_iterator DirKindIt =
      DirectiveKindMap.find(IDVal);
  DirectiveKind DirKind = (DirKindIt == DirectiveKindMap.end())
                              ? DK_NO_DIRECTIVE
                              : DirKindIt->getValue();
  switch (DirKind) {
  default:
    break;
  case DK_IF:
  case DK_IFEQ:
  case DK_IFGE:
  case DK_IFGT:
  case DK_IFLE:
  case DK_IFLT:
  case DK_IFNE:
    return parseDirectiveIf(IDLoc, DirKind);
  case DK_IFB:
    return parseDirectiveIfb(IDLoc, true);
  case DK_IFNB:
    return parseDirectiveIfb(IDLoc, false);
  case DK_IFC:
    return parseDirectiveIfc(IDLoc, true);
  case DK_IFEQS:
    return parseDirectiveIfeqs(IDLoc, true);
  case DK_IFNC:
    return parseDirectiveIfc(IDLoc, false);
  case DK_IFNES:
    return parseDirectiveIfeqs(IDLoc, false);
  case DK_IFDEF:
    return parseDirectiveIfdef(IDLoc, true);
  case DK_IFNDEF:
  case DK_IFNOTDEF:
    return parseDirectiveIfdef(IDLoc, false);
  case DK_ELSEIF:
    return parseDirectiveElseIf(IDLoc);
  case DK_ELSE:
    return parseDirectiveElse(IDLoc);
  case DK_ENDIF:
    return parseDirectiveEndIf(IDLoc);
  }

  // Ignore the statement if in the middle of inactive conditional
  // (e.g. ".if 0").
  if (TheCondState.Ignore) {
    eatToEndOfStatement();
    return false;
  }

  // FIXME: Recurse on local labels?

  // See what kind of statement we have.
  switch (Lexer.getKind()) {
  case AsmToken::Colon: {
    if (!getTargetParser().isLabel(ID))
      break;
    if (checkForValidSection())
      return true;

    // identifier ':'   -> Label.
    Lex();

    // Diagnose attempt to use '.' as a label.
    if (IDVal == ".")
      return Error(IDLoc, "invalid use of pseudo-symbol '.' as a label");

    // Diagnose attempt to use a variable as a label.
    //
    // FIXME: Diagnostics. Note the location of the definition as a label.
    // FIXME: This doesn't diagnose assignment to a symbol which has been
    // implicitly marked as external.
    MCSymbol *Sym;
    if (LocalLabelVal == -1) {
      if (ParsingInlineAsm && SI) {
        StringRef RewrittenLabel =
            SI->LookupInlineAsmLabel(IDVal, getSourceManager(), IDLoc, true);
        assert(!RewrittenLabel.empty() &&
               "We should have an internal name here.");
        Info.AsmRewrites->emplace_back(AOK_Label, IDLoc, IDVal.size(),
                                       RewrittenLabel);
        IDVal = RewrittenLabel;
      }
      Sym = getContext().getOrCreateSymbol(IDVal);
    } else
      Sym = Ctx.createDirectionalLocalSymbol(LocalLabelVal);
    // End of Labels should be treated as end of line for lexing
    // purposes but that information is not available to the Lexer who
    // does not understand Labels. This may cause us to see a Hash
    // here instead of a preprocessor line comment.
    if (getTok().is(AsmToken::Hash)) {
      StringRef CommentStr = parseStringToEndOfStatement();
      Lexer.Lex();
      Lexer.UnLex(AsmToken(AsmToken::EndOfStatement, CommentStr));
    }

    // Consume any end of statement token, if present, to avoid spurious
    // AddBlankLine calls().
    if (getTok().is(AsmToken::EndOfStatement)) {
      Lex();
    }

    // Emit the label.
    if (!getTargetParser().isParsingInlineAsm())
      Out.EmitLabel(Sym, IDLoc);

    // If we are generating dwarf for assembly source files then gather the
    // info to make a dwarf label entry for this label if needed.
    if (enabledGenDwarfForAssembly())
      MCGenDwarfLabelEntry::Make(Sym, &getStreamer(), getSourceManager(),
                                 IDLoc);

    getTargetParser().onLabelParsed(Sym);

    return false;
  }

  case AsmToken::Equal:
    if (!getTargetParser().equalIsAsmAssignment())
      break;
    // identifier '=' ... -> assignment statement
    Lex();

    return parseAssignment(IDVal, true);

  default: // Normal instruction or directive.
    break;
  }

  // If macros are enabled, check to see if this is a macro instantiation.
  if (areMacrosEnabled())
    if (const MCAsmMacro *M = getContext().lookupMacro(IDVal)) {
      return handleMacroEntry(M, IDLoc);
    }

  // Otherwise, we have a normal instruction or directive.

  // Directives start with "."
  if (IDVal[0] == '.' && IDVal != ".") {
    // There are several entities interested in parsing directives:
    //
    // 1. The target-specific assembly parser. Some directives are target
    //    specific or may potentially behave differently on certain targets.
    // 2. Asm parser extensions. For example, platform-specific parsers
    //    (like the ELF parser) register themselves as extensions.
    // 3. The generic directive parser implemented by this class. These are
    //    all the directives that behave in a target and platform independent
    //    manner, or at least have a default behavior that's shared between
    //    all targets and platforms.

    getTargetParser().flushPendingInstructions(getStreamer());

    SMLoc StartTokLoc = getTok().getLoc();
    bool TPDirectiveReturn = getTargetParser().ParseDirective(ID);

    if (hasPendingError())
      return true;
    // Currently the return value should be true if we are
    // uninterested but as this is at odds with the standard parsing
    // convention (return true = error) we have instances of a parsed
    // directive that fails returning true as an error. Catch these
    // cases as best as possible errors here.
    if (TPDirectiveReturn && StartTokLoc != getTok().getLoc())
      return true;
    // Return if we did some parsing or believe we succeeded.
    if (!TPDirectiveReturn || StartTokLoc != getTok().getLoc())
      return false;

    // Next, check the extension directive map to see if any extension has
    // registered itself to parse this directive.
    std::pair<MCAsmParserExtension *, DirectiveHandler> Handler =
        ExtensionDirectiveMap.lookup(IDVal);
    if (Handler.first)
      return (*Handler.second)(Handler.first, IDVal, IDLoc);

    // Finally, if no one else is interested in this directive, it must be
    // generic and familiar to this class.
    switch (DirKind) {
    default:
      break;
    case DK_SET:
    case DK_EQU:
      return parseDirectiveSet(IDVal, true);
    case DK_EQUIV:
      return parseDirectiveSet(IDVal, false);
    case DK_ASCII:
      return parseDirectiveAscii(IDVal, false);
    case DK_ASCIZ:
    case DK_STRING:
      return parseDirectiveAscii(IDVal, true);
    case DK_BYTE:
    case DK_DC_B:
      return parseDirectiveValue(IDVal, 1);
    case DK_DC:
    case DK_DC_W:
    case DK_SHORT:
    case DK_VALUE:
    case DK_2BYTE:
      return parseDirectiveValue(IDVal, 2);
    case DK_LONG:
    case DK_INT:
    case DK_4BYTE:
    case DK_DC_L:
      return parseDirectiveValue(IDVal, 4);
    case DK_QUAD:
    case DK_8BYTE:
      return parseDirectiveValue(IDVal, 8);
    case DK_DC_A:
      return parseDirectiveValue(
          IDVal, getContext().getAsmInfo()->getCodePointerSize());
    case DK_OCTA:
      return parseDirectiveOctaValue(IDVal);
    case DK_SINGLE:
    case DK_FLOAT:
    case DK_DC_S:
      return parseDirectiveRealValue(IDVal, APFloat::IEEEsingle());
    case DK_DOUBLE:
    case DK_DC_D:
      return parseDirectiveRealValue(IDVal, APFloat::IEEEdouble());
    case DK_ALIGN: {
      bool IsPow2 = !getContext().getAsmInfo()->getAlignmentIsInBytes();
      return parseDirectiveAlign(IsPow2, /*ExprSize=*/1);
    }
    case DK_ALIGN32: {
      bool IsPow2 = !getContext().getAsmInfo()->getAlignmentIsInBytes();
      return parseDirectiveAlign(IsPow2, /*ExprSize=*/4);
    }
    case DK_BALIGN:
      return parseDirectiveAlign(/*IsPow2=*/false, /*ExprSize=*/1);
    case DK_BALIGNW:
      return parseDirectiveAlign(/*IsPow2=*/false, /*ExprSize=*/2);
    case DK_BALIGNL:
      return parseDirectiveAlign(/*IsPow2=*/false, /*ExprSize=*/4);
    case DK_P2ALIGN:
      return parseDirectiveAlign(/*IsPow2=*/true, /*ExprSize=*/1);
    case DK_P2ALIGNW:
      return parseDirectiveAlign(/*IsPow2=*/true, /*ExprSize=*/2);
    case DK_P2ALIGNL:
      return parseDirectiveAlign(/*IsPow2=*/true, /*ExprSize=*/4);
    case DK_ORG:
      return parseDirectiveOrg();
    case DK_FILL:
      return parseDirectiveFill();
    case DK_ZERO:
      return parseDirectiveZero();
    case DK_EXTERN:
      eatToEndOfStatement(); // .extern is the default, ignore it.
      return false;
    case DK_GLOBL:
    case DK_GLOBAL:
      return parseDirectiveSymbolAttribute(MCSA_Global);
    case DK_LAZY_REFERENCE:
      return parseDirectiveSymbolAttribute(MCSA_LazyReference);
    case DK_NO_DEAD_STRIP:
      return parseDirectiveSymbolAttribute(MCSA_NoDeadStrip);
    case DK_SYMBOL_RESOLVER:
      return parseDirectiveSymbolAttribute(MCSA_SymbolResolver);
    case DK_PRIVATE_EXTERN:
      return parseDirectiveSymbolAttribute(MCSA_PrivateExtern);
    case DK_REFERENCE:
      return parseDirectiveSymbolAttribute(MCSA_Reference);
    case DK_WEAK_DEFINITION:
      return parseDirectiveSymbolAttribute(MCSA_WeakDefinition);
    case DK_WEAK_REFERENCE:
      return parseDirectiveSymbolAttribute(MCSA_WeakReference);
    case DK_WEAK_DEF_CAN_BE_HIDDEN:
      return parseDirectiveSymbolAttribute(MCSA_WeakDefAutoPrivate);
    case DK_COMM:
    case DK_COMMON:
      return parseDirectiveComm(/*IsLocal=*/false);
    case DK_LCOMM:
      return parseDirectiveComm(/*IsLocal=*/true);
    case DK_ABORT:
      return parseDirectiveAbort();
    case DK_INCLUDE:
      return parseDirectiveInclude();
    case DK_INCBIN:
      return parseDirectiveIncbin();
    case DK_CODE16:
    case DK_CODE16GCC:
      return TokError(Twine(IDVal) +
                      " not currently supported for this target");
    case DK_REPT:
      return parseDirectiveRept(IDLoc, IDVal);
    case DK_IRP:
      return parseDirectiveIrp(IDLoc);
    case DK_IRPC:
      return parseDirectiveIrpc(IDLoc);
    case DK_ENDR:
      return parseDirectiveEndr(IDLoc);
    case DK_BUNDLE_ALIGN_MODE:
      return parseDirectiveBundleAlignMode();
    case DK_BUNDLE_LOCK:
      return parseDirectiveBundleLock();
    case DK_BUNDLE_UNLOCK:
      return parseDirectiveBundleUnlock();
    case DK_SLEB128:
      return parseDirectiveLEB128(true);
    case DK_ULEB128:
      return parseDirectiveLEB128(false);
    case DK_SPACE:
    case DK_SKIP:
      return parseDirectiveSpace(IDVal);
    case DK_FILE:
      return parseDirectiveFile(IDLoc);
    case DK_LINE:
      return parseDirectiveLine();
    case DK_LOC:
      return parseDirectiveLoc();
    case DK_STABS:
      return parseDirectiveStabs();
    case DK_CV_FILE:
      return parseDirectiveCVFile();
    case DK_CV_FUNC_ID:
      return parseDirectiveCVFuncId();
    case DK_CV_INLINE_SITE_ID:
      return parseDirectiveCVInlineSiteId();
    case DK_CV_LOC:
      return parseDirectiveCVLoc();
    case DK_CV_LINETABLE:
      return parseDirectiveCVLinetable();
    case DK_CV_INLINE_LINETABLE:
      return parseDirectiveCVInlineLinetable();
    case DK_CV_DEF_RANGE:
      return parseDirectiveCVDefRange();
    case DK_CV_STRINGTABLE:
      return parseDirectiveCVStringTable();
    case DK_CV_FILECHECKSUMS:
      return parseDirectiveCVFileChecksums();
    case DK_CV_FILECHECKSUM_OFFSET:
      return parseDirectiveCVFileChecksumOffset();
    case DK_CV_FPO_DATA:
      return parseDirectiveCVFPOData();
    case DK_CFI_SECTIONS:
      return parseDirectiveCFISections();
    case DK_CFI_STARTPROC:
      return parseDirectiveCFIStartProc();
    case DK_CFI_ENDPROC:
      return parseDirectiveCFIEndProc();
    case DK_CFI_DEF_CFA:
      return parseDirectiveCFIDefCfa(IDLoc);
    case DK_CFI_DEF_CFA_OFFSET:
      return parseDirectiveCFIDefCfaOffset();
    case DK_CFI_ADJUST_CFA_OFFSET:
      return parseDirectiveCFIAdjustCfaOffset();
    case DK_CFI_DEF_CFA_REGISTER:
      return parseDirectiveCFIDefCfaRegister(IDLoc);
    case DK_CFI_OFFSET:
      return parseDirectiveCFIOffset(IDLoc);
    case DK_CFI_REL_OFFSET:
      return parseDirectiveCFIRelOffset(IDLoc);
    case DK_CFI_PERSONALITY:
      return parseDirectiveCFIPersonalityOrLsda(true);
    case DK_CFI_LSDA:
      return parseDirectiveCFIPersonalityOrLsda(false);
    case DK_CFI_REMEMBER_STATE:
      return parseDirectiveCFIRememberState();
    case DK_CFI_RESTORE_STATE:
      return parseDirectiveCFIRestoreState();
    case DK_CFI_SAME_VALUE:
      return parseDirectiveCFISameValue(IDLoc);
    case DK_CFI_RESTORE:
      return parseDirectiveCFIRestore(IDLoc);
    case DK_CFI_ESCAPE:
      return parseDirectiveCFIEscape();
    case DK_CFI_RETURN_COLUMN:
      return parseDirectiveCFIReturnColumn(IDLoc);
    case DK_CFI_SIGNAL_FRAME:
      return parseDirectiveCFISignalFrame();
    case DK_CFI_UNDEFINED:
      return parseDirectiveCFIUndefined(IDLoc);
    case DK_CFI_REGISTER:
      return parseDirectiveCFIRegister(IDLoc);
    case DK_CFI_WINDOW_SAVE:
      return parseDirectiveCFIWindowSave();
    case DK_MACROS_ON:
    case DK_MACROS_OFF:
      return parseDirectiveMacrosOnOff(IDVal);
    case DK_MACRO:
      return parseDirectiveMacro(IDLoc);
    case DK_ALTMACRO:
    case DK_NOALTMACRO:
      return parseDirectiveAltmacro(IDVal);
    case DK_EXITM:
      return parseDirectiveExitMacro(IDVal);
    case DK_ENDM:
    case DK_ENDMACRO:
      return parseDirectiveEndMacro(IDVal);
    case DK_PURGEM:
      return parseDirectivePurgeMacro(IDLoc);
    case DK_END:
      return parseDirectiveEnd(IDLoc);
    case DK_ERR:
      return parseDirectiveError(IDLoc, false);
    case DK_ERROR:
      return parseDirectiveError(IDLoc, true);
    case DK_WARNING:
      return parseDirectiveWarning(IDLoc);
    case DK_RELOC:
      return parseDirectiveReloc(IDLoc);
    case DK_DCB:
    case DK_DCB_W:
      return parseDirectiveDCB(IDVal, 2);
    case DK_DCB_B:
      return parseDirectiveDCB(IDVal, 1);
    case DK_DCB_D:
      return parseDirectiveRealDCB(IDVal, APFloat::IEEEdouble());
    case DK_DCB_L:
      return parseDirectiveDCB(IDVal, 4);
    case DK_DCB_S:
      return parseDirectiveRealDCB(IDVal, APFloat::IEEEsingle());
    case DK_DC_X:
    case DK_DCB_X:
      return TokError(Twine(IDVal) +
                      " not currently supported for this target");
    case DK_DS:
    case DK_DS_W:
      return parseDirectiveDS(IDVal, 2);
    case DK_DS_B:
      return parseDirectiveDS(IDVal, 1);
    case DK_DS_D:
      return parseDirectiveDS(IDVal, 8);
    case DK_DS_L:
    case DK_DS_S:
      return parseDirectiveDS(IDVal, 4);
    case DK_DS_P:
    case DK_DS_X:
      return parseDirectiveDS(IDVal, 12);
    case DK_PRINT:
      return parseDirectivePrint(IDLoc);
    case DK_ADDRSIG:
      return parseDirectiveAddrsig();
    case DK_ADDRSIG_SYM:
      return parseDirectiveAddrsigSym();
    }

    return Error(IDLoc, "unknown directive");
  }

  // __asm _emit or __asm __emit
  if (ParsingInlineAsm && (IDVal == "_emit" || IDVal == "__emit" ||
                           IDVal == "_EMIT" || IDVal == "__EMIT"))
    return parseDirectiveMSEmit(IDLoc, Info, IDVal.size());

  // __asm align
  if (ParsingInlineAsm && (IDVal == "align" || IDVal == "ALIGN"))
    return parseDirectiveMSAlign(IDLoc, Info);

  if (ParsingInlineAsm && (IDVal == "even" || IDVal == "EVEN"))
    Info.AsmRewrites->emplace_back(AOK_EVEN, IDLoc, 4);
  if (checkForValidSection())
    return true;

  // Canonicalize the opcode to lower case.
  std::string OpcodeStr = IDVal.lower();
  ParseInstructionInfo IInfo(Info.AsmRewrites);
  bool ParseHadError = getTargetParser().ParseInstruction(IInfo, OpcodeStr, ID,
                                                          Info.ParsedOperands);
  Info.ParseError = ParseHadError;

  // Dump the parsed representation, if requested.
  if (getShowParsedOperands()) {
    SmallString<256> Str;
    raw_svector_ostream OS(Str);
    OS << "parsed instruction: [";
    for (unsigned i = 0; i != Info.ParsedOperands.size(); ++i) {
      if (i != 0)
        OS << ", ";
      Info.ParsedOperands[i]->print(OS);
    }
    OS << "]";

    printMessage(IDLoc, SourceMgr::DK_Note, OS.str());
  }

  // Fail even if ParseInstruction erroneously returns false.
  if (hasPendingError() || ParseHadError)
    return true;

  // If we are generating dwarf for the current section then generate a .loc
  // directive for the instruction.
  if (!ParseHadError && enabledGenDwarfForAssembly() &&
      getContext().getGenDwarfSectionSyms().count(
          getStreamer().getCurrentSectionOnly())) {
    unsigned Line;
    if (ActiveMacros.empty())
      Line = SrcMgr.FindLineNumber(IDLoc, CurBuffer);
    else
      Line = SrcMgr.FindLineNumber(ActiveMacros.front()->InstantiationLoc,
                                   ActiveMacros.front()->ExitBuffer);

    // If we previously parsed a cpp hash file line comment then make sure the
    // current Dwarf File is for the CppHashFilename if not then emit the
    // Dwarf File table for it and adjust the line number for the .loc.
    if (!CppHashInfo.Filename.empty()) {
      unsigned FileNumber = getStreamer().EmitDwarfFileDirective(
          0, StringRef(), CppHashInfo.Filename);
      getContext().setGenDwarfFileNumber(FileNumber);

      unsigned CppHashLocLineNo =
        SrcMgr.FindLineNumber(CppHashInfo.Loc, CppHashInfo.Buf);
      Line = CppHashInfo.LineNumber - 1 + (Line - CppHashLocLineNo);
    }

    getStreamer().EmitDwarfLocDirective(
        getContext().getGenDwarfFileNumber(), Line, 0,
        DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0, 0, 0,
        StringRef());
  }

  // If parsing succeeded, match the instruction.
  if (!ParseHadError) {
    uint64_t ErrorInfo;
    if (getTargetParser().MatchAndEmitInstruction(
            IDLoc, Info.Opcode, Info.ParsedOperands, Out, ErrorInfo,
            getTargetParser().isParsingInlineAsm()))
      return true;
  }
  return false;
}

// Parse and erase curly braces marking block start/end
bool
AsmParser::parseCurlyBlockScope(SmallVectorImpl<AsmRewrite> &AsmStrRewrites) {
  // Identify curly brace marking block start/end
  if (Lexer.isNot(AsmToken::LCurly) && Lexer.isNot(AsmToken::RCurly))
    return false;

  SMLoc StartLoc = Lexer.getLoc();
  Lex(); // Eat the brace
  if (Lexer.is(AsmToken::EndOfStatement))
    Lex(); // Eat EndOfStatement following the brace

  // Erase the block start/end brace from the output asm string
  AsmStrRewrites.emplace_back(AOK_Skip, StartLoc, Lexer.getLoc().getPointer() -
                                                  StartLoc.getPointer());
  return true;
}

/// parseCppHashLineFilenameComment as this:
///   ::= # number "filename"
bool AsmParser::parseCppHashLineFilenameComment(SMLoc L) {
  Lex(); // Eat the hash token.
  // Lexer only ever emits HashDirective if it fully formed if it's
  // done the checking already so this is an internal error.
  assert(getTok().is(AsmToken::Integer) &&
         "Lexing Cpp line comment: Expected Integer");
  int64_t LineNumber = getTok().getIntVal();
  Lex();
  assert(getTok().is(AsmToken::String) &&
         "Lexing Cpp line comment: Expected String");
  StringRef Filename = getTok().getString();
  Lex();

  // Get rid of the enclosing quotes.
  Filename = Filename.substr(1, Filename.size() - 2);

  // Save the SMLoc, Filename and LineNumber for later use by diagnostics.
  CppHashInfo.Loc = L;
  CppHashInfo.Filename = Filename;
  CppHashInfo.LineNumber = LineNumber;
  CppHashInfo.Buf = CurBuffer;
  return false;
}

/// will use the last parsed cpp hash line filename comment
/// for the Filename and LineNo if any in the diagnostic.
void AsmParser::DiagHandler(const SMDiagnostic &Diag, void *Context) {
  const AsmParser *Parser = static_cast<const AsmParser *>(Context);
  raw_ostream &OS = errs();

  const SourceMgr &DiagSrcMgr = *Diag.getSourceMgr();
  SMLoc DiagLoc = Diag.getLoc();
  unsigned DiagBuf = DiagSrcMgr.FindBufferContainingLoc(DiagLoc);
  unsigned CppHashBuf =
      Parser->SrcMgr.FindBufferContainingLoc(Parser->CppHashInfo.Loc);

  // Like SourceMgr::printMessage() we need to print the include stack if any
  // before printing the message.
  unsigned DiagCurBuffer = DiagSrcMgr.FindBufferContainingLoc(DiagLoc);
  if (!Parser->SavedDiagHandler && DiagCurBuffer &&
      DiagCurBuffer != DiagSrcMgr.getMainFileID()) {
    SMLoc ParentIncludeLoc = DiagSrcMgr.getParentIncludeLoc(DiagCurBuffer);
    DiagSrcMgr.PrintIncludeStack(ParentIncludeLoc, OS);
  }

  // If we have not parsed a cpp hash line filename comment or the source
  // manager changed or buffer changed (like in a nested include) then just
  // print the normal diagnostic using its Filename and LineNo.
  if (!Parser->CppHashInfo.LineNumber || &DiagSrcMgr != &Parser->SrcMgr ||
      DiagBuf != CppHashBuf) {
    if (Parser->SavedDiagHandler)
      Parser->SavedDiagHandler(Diag, Parser->SavedDiagContext);
    else
      Diag.print(nullptr, OS);
    return;
  }

  // Use the CppHashFilename and calculate a line number based on the
  // CppHashInfo.Loc and CppHashInfo.LineNumber relative to this Diag's SMLoc
  // for the diagnostic.
  const std::string &Filename = Parser->CppHashInfo.Filename;

  int DiagLocLineNo = DiagSrcMgr.FindLineNumber(DiagLoc, DiagBuf);
  int CppHashLocLineNo =
      Parser->SrcMgr.FindLineNumber(Parser->CppHashInfo.Loc, CppHashBuf);
  int LineNo =
      Parser->CppHashInfo.LineNumber - 1 + (DiagLocLineNo - CppHashLocLineNo);

  SMDiagnostic NewDiag(*Diag.getSourceMgr(), Diag.getLoc(), Filename, LineNo,
                       Diag.getColumnNo(), Diag.getKind(), Diag.getMessage(),
                       Diag.getLineContents(), Diag.getRanges());

  if (Parser->SavedDiagHandler)
    Parser->SavedDiagHandler(NewDiag, Parser->SavedDiagContext);
  else
    NewDiag.print(nullptr, OS);
}

// FIXME: This is mostly duplicated from the function in AsmLexer.cpp. The
// difference being that that function accepts '@' as part of identifiers and
// we can't do that. AsmLexer.cpp should probably be changed to handle
// '@' as a special case when needed.
static bool isIdentifierChar(char c) {
  return isalnum(static_cast<unsigned char>(c)) || c == '_' || c == '$' ||
         c == '.';
}

bool AsmParser::expandMacro(raw_svector_ostream &OS, StringRef Body,
                            ArrayRef<MCAsmMacroParameter> Parameters,
                            ArrayRef<MCAsmMacroArgument> A,
                            bool EnableAtPseudoVariable, SMLoc L) {
  unsigned NParameters = Parameters.size();
  bool HasVararg = NParameters ? Parameters.back().Vararg : false;
  if ((!IsDarwin || NParameters != 0) && NParameters != A.size())
    return Error(L, "Wrong number of arguments");

  // A macro without parameters is handled differently on Darwin:
  // gas accepts no arguments and does no substitutions
  while (!Body.empty()) {
    // Scan for the next substitution.
    std::size_t End = Body.size(), Pos = 0;
    for (; Pos != End; ++Pos) {
      // Check for a substitution or escape.
      if (IsDarwin && !NParameters) {
        // This macro has no parameters, look for $0, $1, etc.
        if (Body[Pos] != '$' || Pos + 1 == End)
          continue;

        char Next = Body[Pos + 1];
        if (Next == '$' || Next == 'n' ||
            isdigit(static_cast<unsigned char>(Next)))
          break;
      } else {
        // This macro has parameters, look for \foo, \bar, etc.
        if (Body[Pos] == '\\' && Pos + 1 != End)
          break;
      }
    }

    // Add the prefix.
    OS << Body.slice(0, Pos);

    // Check if we reached the end.
    if (Pos == End)
      break;

    if (IsDarwin && !NParameters) {
      switch (Body[Pos + 1]) {
      // $$ => $
      case '$':
        OS << '$';
        break;

      // $n => number of arguments
      case 'n':
        OS << A.size();
        break;

      // $[0-9] => argument
      default: {
        // Missing arguments are ignored.
        unsigned Index = Body[Pos + 1] - '0';
        if (Index >= A.size())
          break;

        // Otherwise substitute with the token values, with spaces eliminated.
        for (const AsmToken &Token : A[Index])
          OS << Token.getString();
        break;
      }
      }
      Pos += 2;
    } else {
      unsigned I = Pos + 1;

      // Check for the \@ pseudo-variable.
      if (EnableAtPseudoVariable && Body[I] == '@' && I + 1 != End)
        ++I;
      else
        while (isIdentifierChar(Body[I]) && I + 1 != End)
          ++I;

      const char *Begin = Body.data() + Pos + 1;
      StringRef Argument(Begin, I - (Pos + 1));
      unsigned Index = 0;

      if (Argument == "@") {
        OS << NumOfMacroInstantiations;
        Pos += 2;
      } else {
        for (; Index < NParameters; ++Index)
          if (Parameters[Index].Name == Argument)
            break;

        if (Index == NParameters) {
          if (Body[Pos + 1] == '(' && Body[Pos + 2] == ')')
            Pos += 3;
          else {
            OS << '\\' << Argument;
            Pos = I;
          }
        } else {
          bool VarargParameter = HasVararg && Index == (NParameters - 1);
          for (const AsmToken &Token : A[Index])
            // For altmacro mode, you can write '%expr'.
            // The prefix '%' evaluates the expression 'expr'
            // and uses the result as a string (e.g. replace %(1+2) with the string "3").
            // Here, we identify the integer token which is the result of the
            // absolute expression evaluation and replace it with its string representation.
            if ((Lexer.IsaAltMacroMode()) &&
                 (*(Token.getString().begin()) == '%') && Token.is(AsmToken::Integer))
              // Emit an integer value to the buffer.
              OS << Token.getIntVal();
            // Only Token that was validated as a string and begins with '<'
            // is considered altMacroString!!!
            else if ((Lexer.IsaAltMacroMode()) &&
                     (*(Token.getString().begin()) == '<') &&
                     Token.is(AsmToken::String)) {
              std::string Res;
              altMacroString(Token.getStringContents(), Res);
              OS << Res;
            }
            // We expect no quotes around the string's contents when
            // parsing for varargs.
            else if (Token.isNot(AsmToken::String) || VarargParameter)
              OS << Token.getString();
            else
              OS << Token.getStringContents();

          Pos += 1 + Argument.size();
        }
      }
    }
    // Update the scan point.
    Body = Body.substr(Pos);
  }

  return false;
}

MacroInstantiation::MacroInstantiation(SMLoc IL, int EB, SMLoc EL,
                                       size_t CondStackDepth)
    : InstantiationLoc(IL), ExitBuffer(EB), ExitLoc(EL),
      CondStackDepth(CondStackDepth) {}

static bool isOperator(AsmToken::TokenKind kind) {
  switch (kind) {
  default:
    return false;
  case AsmToken::Plus:
  case AsmToken::Minus:
  case AsmToken::Tilde:
  case AsmToken::Slash:
  case AsmToken::Star:
  case AsmToken::Dot:
  case AsmToken::Equal:
  case AsmToken::EqualEqual:
  case AsmToken::Pipe:
  case AsmToken::PipePipe:
  case AsmToken::Caret:
  case AsmToken::Amp:
  case AsmToken::AmpAmp:
  case AsmToken::Exclaim:
  case AsmToken::ExclaimEqual:
  case AsmToken::Less:
  case AsmToken::LessEqual:
  case AsmToken::LessLess:
  case AsmToken::LessGreater:
  case AsmToken::Greater:
  case AsmToken::GreaterEqual:
  case AsmToken::GreaterGreater:
    return true;
  }
}

namespace {

class AsmLexerSkipSpaceRAII {
public:
  AsmLexerSkipSpaceRAII(AsmLexer &Lexer, bool SkipSpace) : Lexer(Lexer) {
    Lexer.setSkipSpace(SkipSpace);
  }

  ~AsmLexerSkipSpaceRAII() {
    Lexer.setSkipSpace(true);
  }

private:
  AsmLexer &Lexer;
};

} // end anonymous namespace

bool AsmParser::parseMacroArgument(MCAsmMacroArgument &MA, bool Vararg) {

  if (Vararg) {
    if (Lexer.isNot(AsmToken::EndOfStatement)) {
      StringRef Str = parseStringToEndOfStatement();
      MA.emplace_back(AsmToken::String, Str);
    }
    return false;
  }

  unsigned ParenLevel = 0;

  // Darwin doesn't use spaces to delmit arguments.
  AsmLexerSkipSpaceRAII ScopedSkipSpace(Lexer, IsDarwin);

  bool SpaceEaten;

  while (true) {
    SpaceEaten = false;
    if (Lexer.is(AsmToken::Eof) || Lexer.is(AsmToken::Equal))
      return TokError("unexpected token in macro instantiation");

    if (ParenLevel == 0) {

      if (Lexer.is(AsmToken::Comma))
        break;

      if (Lexer.is(AsmToken::Space)) {
        SpaceEaten = true;
        Lexer.Lex(); // Eat spaces
      }

      // Spaces can delimit parameters, but could also be part an expression.
      // If the token after a space is an operator, add the token and the next
      // one into this argument
      if (!IsDarwin) {
        if (isOperator(Lexer.getKind())) {
          MA.push_back(getTok());
          Lexer.Lex();

          // Whitespace after an operator can be ignored.
          if (Lexer.is(AsmToken::Space))
            Lexer.Lex();

          continue;
        }
      }
      if (SpaceEaten)
        break;
    }

    // handleMacroEntry relies on not advancing the lexer here
    // to be able to fill in the remaining default parameter values
    if (Lexer.is(AsmToken::EndOfStatement))
      break;

    // Adjust the current parentheses level.
    if (Lexer.is(AsmToken::LParen))
      ++ParenLevel;
    else if (Lexer.is(AsmToken::RParen) && ParenLevel)
      --ParenLevel;

    // Append the token to the current argument list.
    MA.push_back(getTok());
    Lexer.Lex();
  }

  if (ParenLevel != 0)
    return TokError("unbalanced parentheses in macro argument");
  return false;
}

// Parse the macro instantiation arguments.
bool AsmParser::parseMacroArguments(const MCAsmMacro *M,
                                    MCAsmMacroArguments &A) {
  const unsigned NParameters = M ? M->Parameters.size() : 0;
  bool NamedParametersFound = false;
  SmallVector<SMLoc, 4> FALocs;

  A.resize(NParameters);
  FALocs.resize(NParameters);

  // Parse two kinds of macro invocations:
  // - macros defined without any parameters accept an arbitrary number of them
  // - macros defined with parameters accept at most that many of them
  bool HasVararg = NParameters ? M->Parameters.back().Vararg : false;
  for (unsigned Parameter = 0; !NParameters || Parameter < NParameters;
       ++Parameter) {
    SMLoc IDLoc = Lexer.getLoc();
    MCAsmMacroParameter FA;

    if (Lexer.is(AsmToken::Identifier) && Lexer.peekTok().is(AsmToken::Equal)) {
      if (parseIdentifier(FA.Name))
        return Error(IDLoc, "invalid argument identifier for formal argument");

      if (Lexer.isNot(AsmToken::Equal))
        return TokError("expected '=' after formal parameter identifier");

      Lex();

      NamedParametersFound = true;
    }
    bool Vararg = HasVararg && Parameter == (NParameters - 1);

    if (NamedParametersFound && FA.Name.empty())
      return Error(IDLoc, "cannot mix positional and keyword arguments");

    SMLoc StrLoc = Lexer.getLoc();
    SMLoc EndLoc;
    if (Lexer.IsaAltMacroMode() && Lexer.is(AsmToken::Percent)) {
        const MCExpr *AbsoluteExp;
        int64_t Value;
        /// Eat '%'
        Lex();
        if (parseExpression(AbsoluteExp, EndLoc))
          return false;
        if (!AbsoluteExp->evaluateAsAbsolute(Value,
                                             getStreamer().getAssemblerPtr()))
          return Error(StrLoc, "expected absolute expression");
        const char *StrChar = StrLoc.getPointer();
        const char *EndChar = EndLoc.getPointer();
        AsmToken newToken(AsmToken::Integer, StringRef(StrChar , EndChar - StrChar), Value);
        FA.Value.push_back(newToken);
    } else if (Lexer.IsaAltMacroMode() && Lexer.is(AsmToken::Less) &&
               isAltmacroString(StrLoc, EndLoc)) {
        const char *StrChar = StrLoc.getPointer();
        const char *EndChar = EndLoc.getPointer();
        jumpToLoc(EndLoc, CurBuffer);
        /// Eat from '<' to '>'
        Lex();
        AsmToken newToken(AsmToken::String, StringRef(StrChar, EndChar - StrChar));
        FA.Value.push_back(newToken);
    } else if(parseMacroArgument(FA.Value, Vararg))
        return true;

    unsigned PI = Parameter;
    if (!FA.Name.empty()) {
      unsigned FAI = 0;
      for (FAI = 0; FAI < NParameters; ++FAI)
        if (M->Parameters[FAI].Name == FA.Name)
          break;

      if (FAI >= NParameters) {
        assert(M && "expected macro to be defined");
        return Error(IDLoc, "parameter named '" + FA.Name +
                                "' does not exist for macro '" + M->Name + "'");
      }
      PI = FAI;
    }

    if (!FA.Value.empty()) {
      if (A.size() <= PI)
        A.resize(PI + 1);
      A[PI] = FA.Value;

      if (FALocs.size() <= PI)
        FALocs.resize(PI + 1);

      FALocs[PI] = Lexer.getLoc();
    }

    // At the end of the statement, fill in remaining arguments that have
    // default values. If there aren't any, then the next argument is
    // required but missing
    if (Lexer.is(AsmToken::EndOfStatement)) {
      bool Failure = false;
      for (unsigned FAI = 0; FAI < NParameters; ++FAI) {
        if (A[FAI].empty()) {
          if (M->Parameters[FAI].Required) {
            Error(FALocs[FAI].isValid() ? FALocs[FAI] : Lexer.getLoc(),
                  "missing value for required parameter "
                  "'" + M->Parameters[FAI].Name + "' in macro '" + M->Name + "'");
            Failure = true;
          }

          if (!M->Parameters[FAI].Value.empty())
            A[FAI] = M->Parameters[FAI].Value;
        }
      }
      return Failure;
    }

    if (Lexer.is(AsmToken::Comma))
      Lex();
  }

  return TokError("too many positional arguments");
}

bool AsmParser::handleMacroEntry(const MCAsmMacro *M, SMLoc NameLoc) {
  // Arbitrarily limit macro nesting depth (default matches 'as'). We can
  // eliminate this, although we should protect against infinite loops.
  unsigned MaxNestingDepth = AsmMacroMaxNestingDepth;
  if (ActiveMacros.size() == MaxNestingDepth) {
    std::ostringstream MaxNestingDepthError;
    MaxNestingDepthError << "macros cannot be nested more than "
                         << MaxNestingDepth << " levels deep."
                         << " Use -asm-macro-max-nesting-depth to increase "
                            "this limit.";
    return TokError(MaxNestingDepthError.str());
  }

  MCAsmMacroArguments A;
  if (parseMacroArguments(M, A))
    return true;

  // Macro instantiation is lexical, unfortunately. We construct a new buffer
  // to hold the macro body with substitutions.
  SmallString<256> Buf;
  StringRef Body = M->Body;
  raw_svector_ostream OS(Buf);

  if (expandMacro(OS, Body, M->Parameters, A, true, getTok().getLoc()))
    return true;

  // We include the .endmacro in the buffer as our cue to exit the macro
  // instantiation.
  OS << ".endmacro\n";

  std::unique_ptr<MemoryBuffer> Instantiation =
      MemoryBuffer::getMemBufferCopy(OS.str(), "<instantiation>");

  // Create the macro instantiation object and add to the current macro
  // instantiation stack.
  MacroInstantiation *MI = new MacroInstantiation(
      NameLoc, CurBuffer, getTok().getLoc(), TheCondStack.size());
  ActiveMacros.push_back(MI);

  ++NumOfMacroInstantiations;

  // Jump to the macro instantiation and prime the lexer.
  CurBuffer = SrcMgr.AddNewSourceBuffer(std::move(Instantiation), SMLoc());
  Lexer.setBuffer(SrcMgr.getMemoryBuffer(CurBuffer)->getBuffer());
  Lex();

  return false;
}

void AsmParser::handleMacroExit() {
  // Jump to the EndOfStatement we should return to, and consume it.
  jumpToLoc(ActiveMacros.back()->ExitLoc, ActiveMacros.back()->ExitBuffer);
  Lex();

  // Pop the instantiation entry.
  delete ActiveMacros.back();
  ActiveMacros.pop_back();
}

bool AsmParser::parseAssignment(StringRef Name, bool allow_redef,
                                bool NoDeadStrip) {
  MCSymbol *Sym;
  const MCExpr *Value;
  if (MCParserUtils::parseAssignmentExpression(Name, allow_redef, *this, Sym,
                                               Value))
    return true;

  if (!Sym) {
    // In the case where we parse an expression starting with a '.', we will
    // not generate an error, nor will we create a symbol.  In this case we
    // should just return out.
    return false;
  }

  // Do the assignment.
  Out.EmitAssignment(Sym, Value);
  if (NoDeadStrip)
    Out.EmitSymbolAttribute(Sym, MCSA_NoDeadStrip);

  return false;
}

/// parseIdentifier:
///   ::= identifier
///   ::= string
bool AsmParser::parseIdentifier(StringRef &Res) {
  // The assembler has relaxed rules for accepting identifiers, in particular we
  // allow things like '.globl $foo' and '.def @feat.00', which would normally be
  // separate tokens. At this level, we have already lexed so we cannot (currently)
  // handle this as a context dependent token, instead we detect adjacent tokens
  // and return the combined identifier.
  if (Lexer.is(AsmToken::Dollar) || Lexer.is(AsmToken::At)) {
    SMLoc PrefixLoc = getLexer().getLoc();

    // Consume the prefix character, and check for a following identifier.

    AsmToken Buf[1];
    Lexer.peekTokens(Buf, false);

    if (Buf[0].isNot(AsmToken::Identifier))
      return true;

    // We have a '$' or '@' followed by an identifier, make sure they are adjacent.
    if (PrefixLoc.getPointer() + 1 != Buf[0].getLoc().getPointer())
      return true;

    // eat $ or @
    Lexer.Lex(); // Lexer's Lex guarantees consecutive token.
    // Construct the joined identifier and consume the token.
    Res =
        StringRef(PrefixLoc.getPointer(), getTok().getIdentifier().size() + 1);
    Lex(); // Parser Lex to maintain invariants.
    return false;
  }

  if (Lexer.isNot(AsmToken::Identifier) && Lexer.isNot(AsmToken::String))
    return true;

  Res = getTok().getIdentifier();

  Lex(); // Consume the identifier token.

  return false;
}

/// parseDirectiveSet:
///   ::= .equ identifier ',' expression
///   ::= .equiv identifier ',' expression
///   ::= .set identifier ',' expression
bool AsmParser::parseDirectiveSet(StringRef IDVal, bool allow_redef) {
  StringRef Name;
  if (check(parseIdentifier(Name), "expected identifier") ||
      parseToken(AsmToken::Comma) || parseAssignment(Name, allow_redef, true))
    return addErrorSuffix(" in '" + Twine(IDVal) + "' directive");
  return false;
}