llvm-mirror/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.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_MC_MCSTREAMER_H
#define LLVM_MC_MCSTREAMER_H

namespace llvm {
  class MCAtom;
  class MCContext;
  class MCImm;
  class MCInst;
  class MCSection;
  class MCSymbol;
  class raw_ostream;

  /// MCStreamer - Streaming machine code generation interface.
  class MCStreamer {
  public:
    enum SymbolAttr {
      Global,
      Weak,
      PrivateExtern
    };

  private:
    MCContext &Context;

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

  protected:
    MCStreamer(MCContext &Ctx);

  public:
    virtual ~MCStreamer();

    MCContext &getContext() const { return Context; }

    /// SwitchSection - Set the current section where code is being emitted to
    /// @param Section.
    ///
    /// This corresponds to assembler directives like .section, .text, etc.
    virtual void SwitchSection(MCSection *Section) = 0;

    /// EmitLabel - Emit a label for @param 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: What to do about the current section? Should we get rid of the
    // symbol section in the constructor and initialize it here?
    virtual void EmitLabel(MCSymbol *Symbol);

    /// EmitAssignment - Emit an assignment of @param Value to @param 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.
    /// @param MakeAbsolute - If true, then the symbol should be given the
    /// absolute value of @param Value, even if @param Value would be
    /// relocatable expression. This corresponds to the ".set" directive.
    virtual void EmitAssignment(MCSymbol *Symbol, const MCImm &Value,
                                bool MakeAbsolute = false) = 0;

    /// EmitSymbolAttribute - Add the given @param Attribute to @param Symbol.
    //
    // FIXME: This doesn't make much sense, could we just have attributes be on
    // the symbol and make the printer smart enough to add the right symbols?
    // This should work as long as the order of attributes in the file doesn't
    // matter.
    virtual void EmitSymbolAttribute(MCSymbol *Symbol, 
                                     SymbolAttr Attribute) = 0;

    /// EmitBytes - Emit @param Length bytes starting at @param Data into the
    /// output.
    ///
    /// This is used to implement assembler directives such as .byte, .ascii,
    /// etc.
    virtual void EmitBytes(const char *Data, unsigned Length) = 0;

    /// EmitValue - Emit the expression @param Value into the output as a native
    /// integer of the given @param 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.
    virtual void EmitValue(const MCImm &Value, unsigned Size) = 0;

    /// EmitInstruction - Emit the given @param Instruction into the current
    /// section.
    virtual void EmitInstruction(const MCInst &Inst) = 0;
  };

  /// createAsmStreamer - Create a machine code streamer which will print out
  /// assembly for the native target, suitable for compiling with a native
  /// assembler.
  MCStreamer *createAsmStreamer(MCContext &Ctx, raw_ostream &OS);

  // FIXME: These two may end up getting rolled into a single
  // createObjectStreamer interface, which implements the assembler backend, and
  // is parameterized on an output object file writer.

  /// createMachOStream - Create a machine code streamer which will generative
  /// Mach-O format object files.
  MCStreamer *createMachOStreamer(MCContext &Ctx, raw_ostream &OS);

  /// createELFStreamer - Create a machine code streamer which will generative
  /// ELF format object files.
  MCStreamer *createELFStreamer(MCContext &Ctx, raw_ostream &OS);

} // end namespace llvm

#endif