MipsELFStreamer.h

Go to the documentation of this file.

//===- MipsELFStreamer.h - ELF Object Output --------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This is a custom MCELFStreamer which allows us to insert some hooks before
// emitting data into an actual object file.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_LIB_TARGET_MIPS_MCTARGETDESC_MIPSELFSTREAMER_H
#define LLVM_LIB_TARGET_MIPS_MCTARGETDESC_MIPSELFSTREAMER_H

#include "MipsOptionRecord.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/MC/MCELFStreamer.h"
#include <memory>

namespace llvm {

class MCAsmBackend;
class MCCodeEmitter;
class MCContext;
class MCSubtargetInfo;
struct MCDwarfFrameInfo;

class MipsELFStreamer : public MCELFStreamer {
  SmallVector<std::unique_ptr<MipsOptionRecord>, 8> MipsOptionRecords;
  MipsRegInfoRecord *RegInfoRecord;
  SmallVector<MCSymbol*, 4> Labels;

public:
  MipsELFStreamer(MCContext &Context, std::unique_ptr<MCAsmBackend> MAB,
                  std::unique_ptr<MCObjectWriter> OW,
                  std::unique_ptr<MCCodeEmitter> Emitter);

  /// Overriding this function allows us to add arbitrary behaviour before the
  /// \p Inst is actually emitted. For example, we can inspect the operands and
  /// gather sufficient information that allows us to reason about the register
  /// usage for the translation unit.
  void EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI,
                       bool = false) override;

  /// Overriding this function allows us to record all labels that should be
  /// marked as microMIPS. Based on this data marking is done in
  /// EmitInstruction.
  void EmitLabel(MCSymbol *Symbol, SMLoc Loc = SMLoc()) override;

  /// Overriding this function allows us to dismiss all labels that are
  /// candidates for marking as microMIPS when .section directive is processed.
  void SwitchSection(MCSection *Section,
                     const MCExpr *Subsection = nullptr) override;

  /// Overriding these functions allows us to dismiss all labels that are
  /// candidates for marking as microMIPS when .word/.long/.4byte etc
  /// directives are emitted.
  void EmitValueImpl(const MCExpr *Value, unsigned Size, SMLoc Loc) override;
  void EmitIntValue(uint64_t Value, unsigned Size) override;

  // Overriding these functions allows us to avoid recording of these labels
  // in EmitLabel and later marking them as microMIPS.
  void EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) override;
  void EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) override;
  MCSymbol *EmitCFILabel() override;

  /// Emits all the option records stored up until the point it's called.
  void EmitMipsOptionRecords();

  /// Mark labels as microMIPS, if necessary for the subtarget.
  void createPendingLabelRelocs();
};

MCELFStreamer *createMipsELFStreamer(MCContext &Context,
                                     std::unique_ptr<MCAsmBackend> MAB,
                                     std::unique_ptr<MCObjectWriter> OW,
                                     std::unique_ptr<MCCodeEmitter> Emitter,
                                     bool RelaxAll);
} // end namespace llvm

#endif // LLVM_LIB_TARGET_MIPS_MCTARGETDESC_MIPSELFSTREAMER_H