//===- MCStreamer.h - High-level Streaming Machine Code Output --*- C++ -*-===//

//

//                     The LLVM Compiler Infrastructure

//

// This file is distributed under the University of Illinois Open Source

// License. See LICENSE.TXT for details.

//

//===----------------------------------------------------------------------===//

//

// This file declares the MCStreamer class.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_MC_MCSTREAMER_H

#define LLVM_MC_MCSTREAMER_H

#include "llvm/ADT/ArrayRef.h"

#include "llvm/ADT/SmallVector.h"

#include "llvm/MC/MCDirectives.h"

#include "llvm/MC/MCDwarf.h"

#include "llvm/MC/MCLinkerOptimizationHint.h"

#include "llvm/MC/MCSymbol.h"

#include "llvm/MC/MCWinEH.h"

#include "llvm/Support/DataTypes.h"

#include "llvm/Support/SMLoc.h"

#include <string>

namespace llvm_ks {

class MCAsmBackend;

class MCCodeEmitter;

class MCContext;

class MCExpr;

class MCInst;

class MCSection;

class MCStreamer;

class MCSymbolELF;

class MCSymbolRefExpr;

class MCSubtargetInfo;

class StringRef;

class Twine;

class raw_ostream;

class formatted_raw_ostream;

class AssemblerConstantPools;

typedef std::pair<MCSection *, const MCExpr *> MCSectionSubPair;

/// Target specific streamer interface. This is used so that targets can

/// implement support for target specific assembly directives.

///

/// If target foo wants to use this, it should implement 3 classes:

/// * FooTargetStreamer : public MCTargetStreamer

/// * FooTargetAsmStreamer : public FooTargetStreamer

/// * FooTargetELFStreamer : public FooTargetStreamer

///

/// FooTargetStreamer should have a pure virtual method for each directive. For

/// example, for a ".bar symbol_name" directive, it should have

/// virtual emitBar(const MCSymbol &Symbol) = 0;

///

/// The FooTargetAsmStreamer and FooTargetELFStreamer classes implement the

/// method. The assembly streamer just prints ".bar symbol_name". The object

/// streamer does whatever is needed to implement .bar in the object file.

///

/// In the assembly printer and parser the target streamer can be used by

/// calling getTargetStreamer and casting it to FooTargetStreamer:

///

/// MCTargetStreamer &TS = OutStreamer.getTargetStreamer();

/// FooTargetStreamer &ATS = static_cast<FooTargetStreamer &>(TS);

///

/// The base classes FooTargetAsmStreamer and FooTargetELFStreamer should

/// *never* be treated differently. Callers should always talk to a

/// FooTargetStreamer.

class MCTargetStreamer {

protected:

  MCStreamer &Streamer;

public:

  MCTargetStreamer(MCStreamer &S);

  virtual ~MCTargetStreamer();

  MCStreamer &getStreamer() { return Streamer; }

  // Allow a target to add behavior to the EmitLabel of MCStreamer.

  virtual void emitLabel(MCSymbol *Symbol);

  // Allow a target to add behavior to the emitAssignment of MCStreamer.

  virtual void emitAssignment(MCSymbol *Symbol, const MCExpr *Value);

  virtual void finish();

};

// FIXME: declared here because it is used from

// lib/CodeGen/AsmPrinter/ARMException.cpp.

class ARMTargetStreamer : public MCTargetStreamer {

public:

  ARMTargetStreamer(MCStreamer &S);

  ~ARMTargetStreamer() override;

  virtual void emitFnStart();

  virtual void emitFnEnd();

  virtual void emitCantUnwind();

  virtual void emitPersonality(const MCSymbol *Personality);

  virtual void emitPersonalityIndex(unsigned Index);

  virtual void emitHandlerData();

  virtual void emitSetFP(unsigned FpReg, unsigned SpReg,

                         int64_t Offset = 0);

  virtual void emitMovSP(unsigned Reg, int64_t Offset = 0);

  virtual void emitPad(int64_t Offset);

  virtual void emitRegSave(const SmallVectorImpl<unsigned> &RegList,

                           bool isVector);

  virtual void emitUnwindRaw(int64_t StackOffset,

                             const SmallVectorImpl<uint8_t> &Opcodes);

  virtual void switchVendor(StringRef Vendor);

  virtual void emitAttribute(unsigned Attribute, unsigned Value);

  virtual void emitTextAttribute(unsigned Attribute, StringRef String);

  virtual void emitIntTextAttribute(unsigned Attribute, unsigned IntValue,

                                    StringRef StringValue = "");

  virtual void emitFPU(unsigned FPU);

  virtual void emitArch(unsigned Arch);

  virtual void emitArchExtension(unsigned ArchExt);

  virtual void emitObjectArch(unsigned Arch);

  virtual void finishAttributeSection();

  virtual void emitInst(uint32_t Inst, char Suffix = '\0');

  virtual void AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *SRE);

  virtual void emitThumbSet(MCSymbol *Symbol, const MCExpr *Value);

  void finish() override;

  /// Reset any state between object emissions, i.e. the equivalent of

  /// MCStreamer's reset method.

  virtual void reset();

  /// Callback used to implement the ldr= pseudo.

  /// Add a new entry to the constant pool for the current section and return an

  /// MCExpr that can be used to refer to the constant pool location.

  const MCExpr *addConstantPoolEntry(const MCExpr *, SMLoc Loc);

  /// Callback used to implemnt the .ltorg directive.

  /// Emit contents of constant pool for the current section.

  void emitCurrentConstantPool();

private:

  std::unique_ptr<AssemblerConstantPools> ConstantPools;

};

/// \brief Streaming machine code generation interface.

///

/// This interface is intended to provide a programatic interface that is very

/// similar to the level that an assembler .s file provides.  It has callbacks

/// to emit bytes, handle directives, etc.  The implementation of this interface

/// retains state to know what the current section is etc.

///

/// There are multiple implementations of this interface: one for writing out

/// a .s file, and implementations that write out .o files of various formats.

///

class MCStreamer {

  mutable void *KsSymResolver;

  MCContext &Context;

  std::unique_ptr<MCTargetStreamer> TargetStreamer;

  MCStreamer(const MCStreamer &) = delete;

  MCStreamer &operator=(const MCStreamer &) = delete;

  std::vector<MCDwarfFrameInfo> DwarfFrameInfos;

  MCDwarfFrameInfo *getCurrentDwarfFrameInfo();

  void EnsureValidDwarfFrame();

  MCSymbol *EmitCFICommon();

  std::vector<WinEH::FrameInfo *> WinFrameInfos;

  WinEH::FrameInfo *CurrentWinFrameInfo;

  void EnsureValidWinFrameInfo();

  /// \brief Tracks an index to represent the order a symbol was emitted in.

  /// Zero means we did not emit that symbol.

  DenseMap<const MCSymbol *, unsigned> SymbolOrdering;

  /// \brief This is stack of current and previous section values saved by

  /// PushSection.

  SmallVector<std::pair<MCSectionSubPair, MCSectionSubPair>, 4> SectionStack;

protected:

  MCStreamer(MCContext &Ctx);

  virtual void EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame);

  virtual void EmitCFIEndProcImpl(MCDwarfFrameInfo &CurFrame);

  WinEH::FrameInfo *getCurrentWinFrameInfo() {

    return CurrentWinFrameInfo;

  }

  virtual void EmitWindowsUnwindTables();

  virtual void EmitRawTextImpl(StringRef String);

public:

  virtual ~MCStreamer();

  void setSymResolver(void *h) const { KsSymResolver = h; }

  void *getSymResolver() const { return KsSymResolver; }

  void visitUsedExpr(const MCExpr &Expr);

  virtual void visitUsedSymbol(const MCSymbol &Sym);

  void setTargetStreamer(MCTargetStreamer *TS) {

    TargetStreamer.reset(TS);

  }

  /// State management

  ///

  virtual void reset();

  MCContext &getContext() const { return Context; }

  MCTargetStreamer *getTargetStreamer() {

    return TargetStreamer.get();

  }

  unsigned getNumFrameInfos() { return DwarfFrameInfos.size(); }

  ArrayRef<MCDwarfFrameInfo> getDwarfFrameInfos() const {

    return DwarfFrameInfos;

  }

  unsigned getNumWinFrameInfos() { return WinFrameInfos.size(); }

  ArrayRef<WinEH::FrameInfo *> getWinFrameInfos() const {

    return WinFrameInfos;

  }

  void generateCompactUnwindEncodings(MCAsmBackend *MAB);

  // \brief Returns the current size of the fragment to which the streamer

  // is emitting code to.

  virtual uint64_t getCurrentFragmentSize() {return 0; }

  /// \name Assembly File Formatting.

  /// @{

  /// \brief Return true if this streamer supports verbose assembly and if it is

  /// enabled.

  virtual bool isVerboseAsm() const { return false; }

  /// \brief Return true if this asm streamer supports emitting unformatted text

  /// to the .s file with EmitRawText.

  virtual bool hasRawTextSupport() const { return false; }

  /// \brief Is the integrated assembler required for this streamer to function

  /// correctly?

  virtual bool isIntegratedAssemblerRequired() const { return false; }

  /// \brief Add a textual command.

  ///

  /// Typically for comments that can be emitted to the generated .s

  /// file if applicable as a QoI issue to make the output of the compiler

  /// more readable.  This only affects the MCAsmStreamer, and only when

  /// verbose assembly output is enabled.

  ///

  /// If the comment includes embedded \n's, they will each get the comment

  /// prefix as appropriate.  The added comment should not end with a \n.

  virtual void AddComment(const Twine &T) {}

  /// \brief Return a raw_ostream that comments can be written to. Unlike

  /// AddComment, you are required to terminate comments with \n if you use this

  /// method.

  virtual raw_ostream &GetCommentOS();

  /// \brief Print T and prefix it with the comment string (normally #) and

  /// optionally a tab. This prints the comment immediately, not at the end of

  /// the current line. It is basically a safe version of EmitRawText: since it

  /// only prints comments, the object streamer ignores it instead of asserting.

  virtual void emitRawComment(const Twine &T, bool TabPrefix = true);

  /// AddBlankLine - Emit a blank line to a .s file to pretty it up.

  virtual void AddBlankLine() {}

  /// @}

  /// \name Symbol & Section Management

  /// @{

  /// \brief Return the current section that the streamer is emitting code to.

  MCSectionSubPair getCurrentSection() const {

    if (!SectionStack.empty())

      return SectionStack.back().first;

    return MCSectionSubPair();

  }

  MCSection *getCurrentSectionOnly() const { return getCurrentSection().first; }

  /// \brief Return the previous section that the streamer is emitting code to.

  MCSectionSubPair getPreviousSection() const {

    if (!SectionStack.empty())

      return SectionStack.back().second;

    return MCSectionSubPair();

  }

  /// \brief Returns an index to represent the order a symbol was emitted in.

  /// (zero if we did not emit that symbol)

  unsigned GetSymbolOrder(const MCSymbol *Sym) const {

    return SymbolOrdering.lookup(Sym);

  }

  /// \brief Update streamer for a new active section.

  ///

  /// This is called by PopSection and SwitchSection, if the current

  /// section changes.

  virtual void ChangeSection(MCSection *, const MCExpr *);

  /// \brief Save the current and previous section on the section stack.

  void PushSection() {

    SectionStack.push_back(

        std::make_pair(getCurrentSection(), getPreviousSection()));

  }

  /// \brief Restore the current and previous section from the section stack.

  /// Calls ChangeSection as needed.

  ///

  /// Returns false if the stack was empty.

  bool PopSection() {

    if (SectionStack.size() <= 1)

      return false;

    auto I = SectionStack.end();

    --I;

    MCSectionSubPair OldSection = I->first;

    --I;

    MCSectionSubPair NewSection = I->first;

    if (OldSection != NewSection)

      ChangeSection(NewSection.first, NewSection.second);

    SectionStack.pop_back();

    return true;

  }

  bool SubSection(const MCExpr *Subsection) {

    if (SectionStack.empty())

      return false;

    SwitchSection(SectionStack.back().first.first, Subsection);

    return true;

  }

  /// Set the current section where code is being emitted to \p Section.  This

  /// is required to update CurSection.

  ///

  /// This corresponds to assembler directives like .section, .text, etc.

  virtual void SwitchSection(MCSection *Section,

                             const MCExpr *Subsection = nullptr);

  /// \brief Set the current section where code is being emitted to \p Section.

  /// This is required to update CurSection. This version does not call

  /// ChangeSection.

  void SwitchSectionNoChange(MCSection *Section,

                             const MCExpr *Subsection = nullptr) {

    assert(Section && "Cannot switch to a null section!");

    MCSectionSubPair curSection = SectionStack.back().first;

    SectionStack.back().second = curSection;

    if (MCSectionSubPair(Section, Subsection) != curSection)

      SectionStack.back().first = MCSectionSubPair(Section, Subsection);

  }

  /// \brief Create the default sections and set the initial one.

  virtual void InitSections(bool NoExecStack);

  MCSymbol *endSection(MCSection *Section);

  /// \brief Sets the symbol's section.

  ///

  /// Each emitted symbol will be tracked in the ordering table,

  /// so we can sort on them later.

  void AssignFragment(MCSymbol *Symbol, MCFragment *Fragment);

  /// \brief Emit a label for \p Symbol into the current section.

  ///

  /// This corresponds to an assembler statement such as:

  ///   foo:

  ///

  /// \param Symbol - The symbol to emit. A given symbol should only be

  /// emitted as a label once, and symbols emitted as a label should never be

  /// used in an assignment.

  // FIXME: These emission are non-const because we mutate the symbol to

  // add the section we're emitting it to later.

  virtual void EmitLabel(MCSymbol *Symbol);

  virtual void EmitEHSymAttributes(const MCSymbol *Symbol, MCSymbol *EHSymbol);

  /// \brief Note in the output the specified \p Flag.

  virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);

  /// \brief Emit the given list \p Options of strings as linker

  /// options into the output.

  virtual void EmitLinkerOptions(ArrayRef<std::string> Kind) {}

  /// \brief Note in the output the specified region \p Kind.

  virtual void EmitDataRegion(MCDataRegionType Kind) {}

  /// \brief Specify the MachO minimum deployment target version.

  virtual void EmitVersionMin(MCVersionMinType, unsigned Major, unsigned Minor,

                              unsigned Update) {}

  /// \brief Note in the output that the specified \p Func is a Thumb mode

  /// function (ARM target only).

  virtual void EmitThumbFunc(MCSymbol *Func);

  /// \brief Emit an assignment of \p Value to \p Symbol.

  ///

  /// This corresponds to an assembler statement such as:

  ///  symbol = value

  ///

  /// The assignment generates no code, but has the side effect of binding the

  /// value in the current context. For the assembly streamer, this prints the

  /// binding into the .s file.

  ///

  /// \param Symbol - The symbol being assigned to.

  /// \param Value - The value for the symbol.

  virtual bool EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);

  /// \brief Emit an weak reference from \p Alias to \p Symbol.

  ///

  /// This corresponds to an assembler statement such as:

  ///  .weakref alias, symbol

  ///

  /// \param Alias - The alias that is being created.

  /// \param Symbol - The symbol being aliased.

  virtual void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol);

  /// \brief Add the given \p Attribute to \p Symbol.

  virtual bool EmitSymbolAttribute(MCSymbol *Symbol,

                                   MCSymbolAttr Attribute) = 0;

  /// \brief Set the \p DescValue for the \p Symbol.

  ///

  /// \param Symbol - The symbol to have its n_desc field set.

  /// \param DescValue - The value to set into the n_desc field.

  virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);

  /// \brief Start emitting COFF symbol definition

  ///

  /// \param Symbol - The symbol to have its External & Type fields set.

  virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol);

  /// \brief Emit the storage class of the symbol.

  ///

  /// \param StorageClass - The storage class the symbol should have.

  virtual void EmitCOFFSymbolStorageClass(int StorageClass);

  /// \brief Emit the type of the symbol.

  ///

  /// \param Type - A COFF type identifier (see COFF::SymbolType in X86COFF.h)

  virtual void EmitCOFFSymbolType(int Type);

  /// \brief Marks the end of the symbol definition.

  virtual void EndCOFFSymbolDef();

  virtual void EmitCOFFSafeSEH(MCSymbol const *Symbol);

  /// \brief Emits a COFF section index.

  ///

  /// \param Symbol - Symbol the section number relocation should point to.

  virtual void EmitCOFFSectionIndex(MCSymbol const *Symbol);

  /// \brief Emits a COFF section relative relocation.

  ///

  /// \param Symbol - Symbol the section relative relocation should point to.

  virtual void EmitCOFFSecRel32(MCSymbol const *Symbol);

  /// \brief Emit an ELF .size directive.

  ///

  /// This corresponds to an assembler statement such as:

  ///  .size symbol, expression

  virtual void emitELFSize(MCSymbolELF *Symbol, const MCExpr *Value);

  /// \brief Emit a Linker Optimization Hint (LOH) directive.

  /// \param Args - Arguments of the LOH.

  virtual void EmitLOHDirective(MCLOHType Kind, const MCLOHArgs &Args) {}

  /// \brief Emit a common symbol.

  ///

  /// \param Symbol - The common symbol to emit.

  /// \param Size - The size of the common symbol.

  /// \param ByteAlignment - The alignment of the symbol if

  /// non-zero. This must be a power of 2.

  virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,

                                unsigned ByteAlignment) = 0;

  /// \brief Emit a local common (.lcomm) symbol.

  ///

  /// \param Symbol - The common symbol to emit.

  /// \param Size - The size of the common symbol.

  /// \param ByteAlignment - The alignment of the common symbol in bytes.

  virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,

                                     unsigned ByteAlignment);

  /// \brief Emit the zerofill section and an optional symbol.

  ///

  /// \param Section - The zerofill section to create and or to put the symbol

  /// \param Symbol - The zerofill symbol to emit, if non-NULL.

  /// \param Size - The size of the zerofill symbol.

  /// \param ByteAlignment - The alignment of the zerofill symbol if

  /// non-zero. This must be a power of 2 on some targets.

  virtual void EmitZerofill(MCSection *Section, MCSymbol *Symbol = nullptr,

                            uint64_t Size = 0, unsigned ByteAlignment = 0) = 0;

  /// \brief Emit a thread local bss (.tbss) symbol.

  ///

  /// \param Section - The thread local common section.

  /// \param Symbol - The thread local common symbol to emit.

  /// \param Size - The size of the symbol.

  /// \param ByteAlignment - The alignment of the thread local common symbol

  /// if non-zero.  This must be a power of 2 on some targets.

  virtual void EmitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,

                              uint64_t Size, unsigned ByteAlignment = 0);

  /// @}

  /// \name Generating Data

  /// @{

  /// \brief Emit the bytes in \p Data into the output.

  ///

  /// This is used to implement assembler directives such as .byte, .ascii,

  /// etc.

  virtual void EmitBytes(StringRef Data);

  /// \brief Emit the expression \p Value into the output as a native

  /// integer of the given \p Size bytes.

  ///

  /// This is used to implement assembler directives such as .word, .quad,

  /// etc.

  ///

  /// \param Value - The value to emit.

  /// \param Size - The size of the integer (in bytes) to emit. This must

  /// match a native machine width.

  /// \param Loc - The location of the expression for error reporting.

  virtual void EmitValueImpl(const MCExpr *Value, unsigned Size,

                             SMLoc Loc = SMLoc());

  void EmitValue(const MCExpr *Value, unsigned Size, SMLoc Loc = SMLoc());

  /// \brief Special case of EmitValue that avoids the client having

  /// to pass in a MCExpr for constant integers.

  virtual void EmitIntValue(uint64_t Value, unsigned Size, bool &Error);

  virtual void EmitULEB128Value(const MCExpr *Value);

  virtual void EmitSLEB128Value(const MCExpr *Value);

  /// \brief Special case of EmitULEB128Value that avoids the client having to

  /// pass in a MCExpr for constant integers.

  void EmitULEB128IntValue(uint64_t Value, unsigned Padding = 0);

  /// \brief Special case of EmitSLEB128Value that avoids the client having to

  /// pass in a MCExpr for constant integers.

  void EmitSLEB128IntValue(int64_t Value);

  /// \brief Special case of EmitValue that avoids the client having to pass in

  /// a MCExpr for MCSymbols.

  void EmitSymbolValue(const MCSymbol *Sym, unsigned Size,

                       bool IsSectionRelative = false);

  /// \brief Emit the expression \p Value into the output as a gprel64 (64-bit

  /// GP relative) value.

  ///

  /// This is used to implement assembler directives such as .gpdword on

  /// targets that support them.

  virtual void EmitGPRel64Value(const MCExpr *Value);

  /// \brief Emit the expression \p Value into the output as a gprel32 (32-bit

  /// GP relative) value.

  ///

  /// This is used to implement assembler directives such as .gprel32 on

  /// targets that support them.

  virtual void EmitGPRel32Value(const MCExpr *Value);

  /// \brief Emit NumBytes bytes worth of the value specified by FillValue.

  /// This implements directives such as '.space'.

  virtual void EmitFill(uint64_t NumBytes, uint8_t FillValue);

  /// \brief Emit NumBytes worth of zeros.

  /// This function properly handles data in virtual sections.

  void EmitZeros(uint64_t NumBytes);

  /// \brief Emit some number of copies of \p Value until the byte alignment \p

  /// ByteAlignment is reached.

  ///

  /// If the number of bytes need to emit for the alignment is not a multiple

  /// of \p ValueSize, then the contents of the emitted fill bytes is

  /// undefined.

  ///

  /// This used to implement the .align assembler directive.

  ///

  /// \param ByteAlignment - The alignment to reach. This must be a power of

  /// two on some targets.

  /// \param Value - The value to use when filling bytes.

  /// \param ValueSize - The size of the integer (in bytes) to emit for

  /// \p Value. This must match a native machine width.

  /// \param MaxBytesToEmit - The maximum numbers of bytes to emit, or 0. If

  /// the alignment cannot be reached in this many bytes, no bytes are

  /// emitted.

  virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,

                                    unsigned ValueSize = 1,

                                    unsigned MaxBytesToEmit = 0);

  /// \brief Emit nops until the byte alignment \p ByteAlignment is reached.

  ///

  /// This used to align code where the alignment bytes may be executed.  This

  /// can emit different bytes for different sizes to optimize execution.

  ///

  /// \param ByteAlignment - The alignment to reach. This must be a power of

  /// two on some targets.

  /// \param MaxBytesToEmit - The maximum numbers of bytes to emit, or 0. If

  /// the alignment cannot be reached in this many bytes, no bytes are

  /// emitted.

  virtual void EmitCodeAlignment(unsigned ByteAlignment,

                                 unsigned MaxBytesToEmit = 0);

  /// \brief Emit some number of copies of \p Value until the byte offset \p

  /// Offset is reached.

  ///

  /// This is used to implement assembler directives such as .org.

  ///

  /// \param Offset - The offset to reach. This may be an expression, but the

  /// expression must be associated with the current section.

  /// \param Value - The value to use when filling bytes.

  virtual void emitValueToOffset(const MCExpr *Offset, unsigned char Value = 0);

  /// @}

  /// \brief Switch to a new logical file.  This is used to implement the '.file

  /// "foo.c"' assembler directive.

  virtual void EmitFileDirective(StringRef Filename);

  /// \brief Emit the "identifiers" directive.  This implements the

  /// '.ident "version foo"' assembler directive.

  virtual void EmitIdent(StringRef IdentString) {}

  /// \brief Associate a filename with a specified logical file number.  This

  /// implements the DWARF2 '.file 4 "foo.c"' assembler directive.

  virtual unsigned EmitDwarfFileDirective(unsigned FileNo, StringRef Directory,

                                          StringRef Filename,

                                          unsigned CUID = 0);

  /// \brief This implements the DWARF2 '.loc fileno lineno ...' assembler

  /// directive.

  virtual void EmitDwarfLocDirective(unsigned FileNo, unsigned Line,

                                     unsigned Column, unsigned Flags,

                                     unsigned Isa, unsigned Discriminator,

                                     StringRef FileName);

  /// \brief Associate a filename with a specified logical file number.  This

  /// implements the '.cv_file 4 "foo.c"' assembler directive.

  virtual unsigned EmitCVFileDirective(unsigned FileNo, StringRef Filename);

  /// \brief This implements the CodeView '.cv_loc' assembler directive.

  virtual void EmitCVLocDirective(unsigned FunctionId, unsigned FileNo,

                                  unsigned Line, unsigned Column,

                                  bool PrologueEnd, bool IsStmt,

                                  StringRef FileName);

  /// \brief This implements the CodeView '.cv_linetable' assembler directive.

  virtual void EmitCVLinetableDirective(unsigned FunctionId,

                                        const MCSymbol *FnStart,

                                        const MCSymbol *FnEnd);

  /// \brief This implements the CodeView '.cv_inline_linetable' assembler

  /// directive.

  virtual void

  EmitCVInlineLinetableDirective(unsigned PrimaryFunctionId,

                                 unsigned SourceFileId, unsigned SourceLineNum,

                                 ArrayRef<unsigned> SecondaryFunctionIds);

  /// \brief This implements the CodeView '.cv_stringtable' assembler directive.

  virtual void EmitCVStringTableDirective() {}

  /// \brief This implements the CodeView '.cv_filechecksums' assembler directive.

  virtual void EmitCVFileChecksumsDirective() {}

  /// Emit the absolute difference between two symbols.

  ///

  /// \pre Offset of \c Hi is greater than the offset \c Lo.

  virtual void emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo,

                                      unsigned Size);

  virtual MCSymbol *getDwarfLineTableSymbol(unsigned CUID);

  virtual void EmitCFISections(bool EH, bool Debug);

  void EmitCFIStartProc(bool IsSimple);

  void EmitCFIEndProc();

  virtual void EmitCFIDefCfa(int64_t Register, int64_t Offset);

  virtual void EmitCFIDefCfaOffset(int64_t Offset);

  virtual void EmitCFIDefCfaRegister(int64_t Register);

  virtual void EmitCFIOffset(int64_t Register, int64_t Offset);

  virtual void EmitCFIPersonality(const MCSymbol *Sym, unsigned Encoding);

  virtual void EmitCFILsda(const MCSymbol *Sym, unsigned Encoding);

  virtual void EmitCFIRememberState();

  virtual void EmitCFIRestoreState();

  virtual void EmitCFISameValue(int64_t Register);

  virtual void EmitCFIRestore(int64_t Register);

  virtual void EmitCFIRelOffset(int64_t Register, int64_t Offset);

  virtual void EmitCFIAdjustCfaOffset(int64_t Adjustment);

  virtual void EmitCFIEscape(StringRef Values);

  virtual void EmitCFIGnuArgsSize(int64_t Size);

  virtual void EmitCFISignalFrame();

  virtual void EmitCFIUndefined(int64_t Register);

  virtual void EmitCFIRegister(int64_t Register1, int64_t Register2);

  virtual void EmitCFIWindowSave();

  virtual void EmitWinCFIStartProc(const MCSymbol *Symbol);

  virtual void EmitWinCFIEndProc();

  virtual void EmitWinCFIStartChained();

  virtual void EmitWinCFIEndChained();

  virtual void EmitWinCFIPushReg(unsigned Register);

  virtual void EmitWinCFISetFrame(unsigned Register, unsigned Offset);

  virtual void EmitWinCFIAllocStack(unsigned Size);

  virtual void EmitWinCFISaveReg(unsigned Register, unsigned Offset);

  virtual void EmitWinCFISaveXMM(unsigned Register, unsigned Offset);

  virtual void EmitWinCFIPushFrame(bool Code);

  virtual void EmitWinCFIEndProlog();

  virtual void EmitWinEHHandler(const MCSymbol *Sym, bool Unwind, bool Except);

  virtual void EmitWinEHHandlerData();

  virtual void EmitSyntaxDirective();

  /// \brief Emit a .reloc directive.

  /// Returns true if the relocation could not be emitted because Name is not

  /// known.

  virtual bool EmitRelocDirective(const MCExpr &Offset, StringRef Name,

                                  const MCExpr *Expr, SMLoc Loc) {

    return true;

  }

  /// \brief Emit the given \p Instruction into the current section.

  virtual void EmitInstruction(MCInst &Inst, const MCSubtargetInfo &STI, unsigned int &KsError);

  /// \brief Set the bundle alignment mode from now on in the section.

  /// The argument is the power of 2 to which the alignment is set. The

  /// value 0 means turn the bundle alignment off.

  virtual void EmitBundleAlignMode(unsigned AlignPow2);

  /// \brief The following instructions are a bundle-locked group.

  ///

  /// \param AlignToEnd - If true, the bundle-locked group will be aligned to

  ///                     the end of a bundle.

  virtual void EmitBundleLock(bool AlignToEnd);

  /// \brief Ends a bundle-locked group.

  virtual void EmitBundleUnlock();

  /// \brief If this file is backed by a assembly streamer, this dumps the

  /// specified string in the output .s file.  This capability is indicated by

  /// the hasRawTextSupport() predicate.  By default this aborts.

  void EmitRawText(const Twine &String);

  /// \brief Streamer specific finalization.

  virtual unsigned int FinishImpl();

  /// \brief Finish emission of machine code.

  unsigned int Finish();

  virtual bool mayHaveInstructions(MCSection &Sec) const { return true; }

};

/// Create a dummy machine code streamer, which does nothing. This is useful for

/// timing the assembler front end.

MCStreamer *createNullStreamer(MCContext &Ctx);

/// Create a machine code streamer which will print out assembly for the native

/// target, suitable for compiling with a native assembler.

///

/// \param CE - If given, a code emitter to use to show the instruction

/// encoding inline with the assembly. This method takes ownership of \p CE.

///

/// \param TAB - If given, a target asm backend to use to show the fixup

/// information in conjunction with encoding information. This method takes

/// ownership of \p TAB.

MCStreamer *createAsmStreamer(MCContext &Ctx,

                              std::unique_ptr<formatted_raw_ostream> OS,

                              MCCodeEmitter *CE,

                              MCAsmBackend *TAB);

} // end namespace llvm_ks

#endif