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      1 //===- MCObjectStreamer.h - MCStreamer Object File Interface ----*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 
     10 #ifndef LLVM_MC_MCOBJECTSTREAMER_H
     11 #define LLVM_MC_MCOBJECTSTREAMER_H
     12 
     13 #include "llvm/MC/MCAssembler.h"
     14 #include "llvm/MC/MCStreamer.h"
     15 
     16 namespace llvm {
     17 class MCAssembler;
     18 class MCCodeEmitter;
     19 class MCSectionData;
     20 class MCSubtargetInfo;
     21 class MCExpr;
     22 class MCFragment;
     23 class MCDataFragment;
     24 class MCAsmBackend;
     25 class raw_ostream;
     26 
     27 /// \brief Streaming object file generation interface.
     28 ///
     29 /// This class provides an implementation of the MCStreamer interface which is
     30 /// suitable for use with the assembler backend. Specific object file formats
     31 /// are expected to subclass this interface to implement directives specific
     32 /// to that file format or custom semantics expected by the object writer
     33 /// implementation.
     34 class MCObjectStreamer : public MCStreamer {
     35   MCAssembler *Assembler;
     36   MCSectionData *CurSectionData;
     37   MCSectionData::iterator CurInsertionPoint;
     38   bool EmitEHFrame;
     39   bool EmitDebugFrame;
     40 
     41   virtual void EmitInstToData(const MCInst &Inst, const MCSubtargetInfo&) = 0;
     42   void EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) override;
     43   void EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) override;
     44 
     45 protected:
     46   MCObjectStreamer(MCContext &Context, MCAsmBackend &TAB, raw_ostream &_OS,
     47                    MCCodeEmitter *_Emitter);
     48   MCObjectStreamer(MCContext &Context, MCAsmBackend &TAB, raw_ostream &_OS,
     49                    MCCodeEmitter *_Emitter, MCAssembler *_Assembler);
     50   ~MCObjectStreamer();
     51 
     52 public:
     53   /// state management
     54   void reset() override;
     55 
     56   /// Object streamers require the integrated assembler.
     57   bool isIntegratedAssemblerRequired() const override { return true; }
     58 
     59   MCSymbolData &getOrCreateSymbolData(const MCSymbol *Symbol) {
     60     return getAssembler().getOrCreateSymbolData(*Symbol);
     61   }
     62   void EmitFrames(MCAsmBackend *MAB);
     63   void EmitCFISections(bool EH, bool Debug) override;
     64 
     65 protected:
     66   MCSectionData *getCurrentSectionData() const {
     67     return CurSectionData;
     68   }
     69 
     70   MCFragment *getCurrentFragment() const;
     71 
     72   void insert(MCFragment *F) const {
     73     CurSectionData->getFragmentList().insert(CurInsertionPoint, F);
     74     F->setParent(CurSectionData);
     75   }
     76 
     77   /// Get a data fragment to write into, creating a new one if the current
     78   /// fragment is not a data fragment.
     79   MCDataFragment *getOrCreateDataFragment() const;
     80 
     81 public:
     82   void visitUsedSymbol(const MCSymbol &Sym) override;
     83 
     84   MCAssembler &getAssembler() { return *Assembler; }
     85 
     86   /// @name MCStreamer Interface
     87   /// @{
     88 
     89   void EmitLabel(MCSymbol *Symbol) override;
     90   void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) override;
     91   void EmitValueImpl(const MCExpr *Value, unsigned Size,
     92                      const SMLoc &Loc = SMLoc()) override;
     93   void EmitULEB128Value(const MCExpr *Value) override;
     94   void EmitSLEB128Value(const MCExpr *Value) override;
     95   void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) override;
     96   void ChangeSection(const MCSection *Section,
     97                      const MCExpr *Subsection) override;
     98   void EmitInstruction(const MCInst &Inst, const MCSubtargetInfo& STI) override;
     99 
    100   /// \brief Emit an instruction to a special fragment, because this instruction
    101   /// can change its size during relaxation.
    102   virtual void EmitInstToFragment(const MCInst &Inst, const MCSubtargetInfo &);
    103 
    104   void EmitBundleAlignMode(unsigned AlignPow2) override;
    105   void EmitBundleLock(bool AlignToEnd) override;
    106   void EmitBundleUnlock() override;
    107   void EmitBytes(StringRef Data) override;
    108   void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
    109                             unsigned ValueSize = 1,
    110                             unsigned MaxBytesToEmit = 0) override;
    111   void EmitCodeAlignment(unsigned ByteAlignment,
    112                          unsigned MaxBytesToEmit = 0) override;
    113   bool EmitValueToOffset(const MCExpr *Offset, unsigned char Value) override;
    114   void EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
    115                              unsigned Column, unsigned Flags,
    116                              unsigned Isa, unsigned Discriminator,
    117                              StringRef FileName) override;
    118   void EmitDwarfAdvanceLineAddr(int64_t LineDelta, const MCSymbol *LastLabel,
    119                                 const MCSymbol *Label,
    120                                 unsigned PointerSize);
    121   void EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
    122                                  const MCSymbol *Label);
    123   void EmitGPRel32Value(const MCExpr *Value) override;
    124   void EmitGPRel64Value(const MCExpr *Value) override;
    125   void EmitFill(uint64_t NumBytes, uint8_t FillValue) override;
    126   void EmitZeros(uint64_t NumBytes) override;
    127   void FinishImpl() override;
    128 
    129   virtual bool mayHaveInstructions() const {
    130     return getCurrentSectionData()->hasInstructions();
    131   }
    132 };
    133 
    134 } // end namespace llvm
    135 
    136 #endif
    137