path: root/include/llvm/MC/MCStreamer.h

//===- 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/SmallVector.h"
#include "llvm/Support/DataTypes.h"
#include "llvm/MC/MCDirectives.h"
#include "llvm/MC/MCDwarf.h"

namespace llvm {
  class MCAsmInfo;
  class MCCodeEmitter;
  class MCContext;
  class MCExpr;
  class MCInst;
  class MCInstPrinter;
  class MCSection;
  class MCSymbol;
  class StringRef;
  class TargetAsmBackend;
  class TargetLoweringObjectFile;
  class Twine;
  class raw_ostream;
  class formatted_raw_ostream;

  /// MCStreamer - 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 {
    MCContext &Context;

    MCStreamer(const MCStreamer&); // DO NOT IMPLEMENT
    MCStreamer &operator=(const MCStreamer&); // DO NOT IMPLEMENT

    void EmitSymbolValue(const MCSymbol *Sym, unsigned Size,
                         bool isPCRel, unsigned AddrSpace);

    std::vector<MCDwarfFrameInfo> FrameInfos;
    MCDwarfFrameInfo *getCurrentFrameInfo();
    void EnsureValidFrame();

    /// SectionStack - This is stack of current and previous section
    /// values saved by PushSection.
    SmallVector<std::pair<const MCSection *,
                const MCSection *>, 4> SectionStack;

  protected:
    MCStreamer(MCContext &Ctx);

  public:
    virtual ~MCStreamer();

    MCContext &getContext() const { return Context; }

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

    const MCDwarfFrameInfo &getFrameInfo(unsigned i) {
      return FrameInfos[i];
    }

    /// @name Assembly File Formatting.
    /// @{

    /// isVerboseAsm - Return true if this streamer supports verbose assembly
    /// and if it is enabled.
    virtual bool isVerboseAsm() const { return false; }

    /// hasRawTextSupport - Return true if this asm streamer supports emitting
    /// unformatted text to the .s file with EmitRawText.
    virtual bool hasRawTextSupport() const { return false; }

    /// AddComment - Add a comment 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) {}

    /// GetCommentOS - 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();

    /// AddBlankLine - Emit a blank line to a .s file to pretty it up.
    virtual void AddBlankLine() {}

    /// @}

    /// @name Symbol & Section Management
    /// @{

    /// getCurrentSection - Return the current section that the streamer is
    /// emitting code to.
    const MCSection *getCurrentSection() const {
      if (!SectionStack.empty())
        return SectionStack.back().first;
      return NULL;
    }

    /// getPreviousSection - Return the previous section that the streamer is
    /// emitting code to.
    const MCSection *getPreviousSection() const {
      if (!SectionStack.empty())
        return SectionStack.back().second;
      return NULL;
    }

    /// ChangeSection - Update streamer for a new active section.
    ///
    /// This is called by PopSection and SwitchSection, if the current
    /// section changes.
    virtual void ChangeSection(const MCSection *) = 0;

    /// pushSection - Save the current and previous section on the
    /// section stack.
    void PushSection() {
      SectionStack.push_back(std::make_pair(getCurrentSection(),
                                            getPreviousSection()));
    }

    /// popSection - 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;
      const MCSection *oldSection = SectionStack.pop_back_val().first;
      const MCSection *curSection = SectionStack.back().first;

      if (oldSection != curSection)
        ChangeSection(curSection);
      return true;
    }

    /// SwitchSection - 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.
    void SwitchSection(const MCSection *Section) {
      assert(Section && "Cannot switch to a null section!");
      const MCSection *curSection = SectionStack.back().first;
      SectionStack.back().second = curSection;
      if (Section != curSection) {
        SectionStack.back().first = Section;
        ChangeSection(Section);
      }
    }

    /// InitSections - Create the default sections and set the initial one.
    virtual void InitSections() = 0;

    /// EmitLabel - 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.
    virtual void EmitLabel(MCSymbol *Symbol) = 0;

    /// EmitAssemblerFlag - Note in the output the specified @p Flag
    virtual void EmitAssemblerFlag(MCAssemblerFlag Flag) = 0;

    /// EmitThumbFunc - Note in the output that the specified @p Func is
    /// a Thumb mode function (ARM target only).
    virtual void EmitThumbFunc(MCSymbol *Func) = 0;

    /// EmitAssignment - 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 void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) = 0;

    /// EmitWeakReference - 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) = 0;

    /// EmitSymbolAttribute - Add the given @p Attribute to @p Symbol.
    virtual void EmitSymbolAttribute(MCSymbol *Symbol,
                                     MCSymbolAttr Attribute) = 0;

    /// EmitSymbolDesc - 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) = 0;

    /// BeginCOFFSymbolDef - Start emitting COFF symbol definition
    ///
    /// @param Symbol - The symbol to have its External & Type fields set.
    virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol) = 0;

    /// EmitCOFFSymbolStorageClass - Emit the storage class of the symbol.
    ///
    /// @param StorageClass - The storage class the symbol should have.
    virtual void EmitCOFFSymbolStorageClass(int StorageClass) = 0;

    /// EmitCOFFSymbolType - Emit the type of the symbol.
    ///
    /// @param Type - A COFF type identifier (see COFF::SymbolType in X86COFF.h)
    virtual void EmitCOFFSymbolType(int Type) = 0;

    /// EndCOFFSymbolDef - Marks the end of the symbol definition.
    virtual void EndCOFFSymbolDef() = 0;

    /// EmitELFSize - Emit an ELF .size directive.
    ///
    /// This corresponds to an assembler statement such as:
    ///  .size symbol, expression
    ///
    virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) = 0;

    /// EmitCommonSymbol - 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;

    /// EmitLocalCommonSymbol - Emit a local common (.lcomm) symbol.
    ///
    /// @param Symbol - The common symbol to emit.
    /// @param Size - The size of the common symbol.
    virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) = 0;

    /// EmitZerofill - 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(const MCSection *Section, MCSymbol *Symbol = 0,
                              unsigned Size = 0,unsigned ByteAlignment = 0) = 0;

    /// EmitTBSSSymbol - Emit a thread local bss (.tbss) symbol.
    ///
    /// @param Section - The th