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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/ADT/SmallVector.h"
     14 #include "llvm/MC/MCAssembler.h"
     15 #include "llvm/MC/MCSection.h"
     16 #include "llvm/MC/MCStreamer.h"
     17 
     18 namespace llvm {
     19 class MCAssembler;
     20 class MCCodeEmitter;
     21 class MCSubtargetInfo;
     22 class MCExpr;
     23 class MCFragment;
     24 class MCDataFragment;
     25 class MCAsmBackend;
     26 class raw_ostream;
     27 class raw_pwrite_stream;
     28 
     29 /// \brief Streaming object file generation interface.
     30 ///
     31 /// This class provides an implementation of the MCStreamer interface which is
     32 /// suitable for use with the assembler backend. Specific object file formats
     33 /// are expected to subclass this interface to implement directives specific
     34 /// to that file format or custom semantics expected by the object writer
     35 /// implementation.
     36 class MCObjectStreamer : public MCStreamer {
     37   MCAssembler *Assembler;
     38   MCSection::iterator CurInsertionPoint;
     39   bool EmitEHFrame;
     40   bool EmitDebugFrame;
     41   SmallVector<MCSymbol *, 2> PendingLabels;
     42 
     43   virtual void EmitInstToData(const MCInst &Inst, const MCSubtargetInfo&) = 0;
     44   void EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) override;
     45   void EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) override;
     46 
     47 protected:
     48   MCObjectStreamer(MCContext &Context, MCAsmBackend &TAB, raw_pwrite_stream &OS,
     49                    MCCodeEmitter *Emitter);
     50   ~MCObjectStreamer() override;
     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   void EmitFrames(MCAsmBackend *MAB);
     60   void EmitCFISections(bool EH, bool Debug) override;
     61 
     62   MCFragment *getCurrentFragment() const;
     63 
     64   void insert(MCFragment *F) {
     65     flushPendingLabels(F);
     66     MCSection *CurSection = getCurrentSectionOnly();
     67     CurSection->getFragmentList().insert(CurInsertionPoint, F);
     68     F->setParent(CurSection);
     69   }
     70 
     71   /// Get a data fragment to write into, creating a new one if the current
     72   /// fragment is not a data fragment.
     73   MCDataFragment *getOrCreateDataFragment();
     74 
     75 protected:
     76   bool changeSectionImpl(MCSection *Section, const MCExpr *Subsection);
     77 
     78   /// If any labels have been emitted but not assigned fragments, ensure that
     79   /// they get assigned, either to F if possible or to a new data fragment.
     80   /// Optionally, it is also possible to provide an offset \p FOffset, which
     81   /// will be used as a symbol offset within the fragment.
     82   void flushPendingLabels(MCFragment *F, uint64_t FOffset = 0);
     83 
     84 public:
     85   void visitUsedSymbol(const MCSymbol &Sym) override;
     86 
     87   MCAssembler &getAssembler() { return *Assembler; }
     88 
     89   /// \name MCStreamer Interface
     90   /// @{
     91 
     92   void EmitLabel(MCSymbol *Symbol) override;
     93   void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) override;
     94   void EmitValueImpl(const MCExpr *Value, unsigned Size,
     95                      SMLoc Loc = SMLoc()) override;
     96   void EmitULEB128Value(const MCExpr *Value) override;
     97   void EmitSLEB128Value(const MCExpr *Value) override;
     98   void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) override;
     99   void ChangeSection(MCSection *Section, const MCExpr *Subsection) override;
    100   void EmitInstruction(const MCInst &Inst, const MCSubtargetInfo& STI) override;
    101 
    102   /// \brief Emit an instruction to a special fragment, because this instruction
    103   /// can change its size during relaxation.
    104   virtual void EmitInstToFragment(const MCInst &Inst, const MCSubtargetInfo &);
    105 
    106   void EmitBundleAlignMode(unsigned AlignPow2) override;
    107   void EmitBundleLock(bool AlignToEnd) override;
    108   void EmitBundleUnlock() override;
    109   void EmitBytes(StringRef Data) override;
    110   void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
    111                             unsigned ValueSize = 1,
    112                             unsigned MaxBytesToEmit = 0) override;
    113   void EmitCodeAlignment(unsigned ByteAlignment,
    114                          unsigned MaxBytesToEmit = 0) override;
    115   void emitValueToOffset(const MCExpr *Offset, unsigned char Value) override;
    116   void EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
    117                              unsigned Column, unsigned Flags,
    118                              unsigned Isa, unsigned Discriminator,
    119                              StringRef FileName) override;
    120   void EmitDwarfAdvanceLineAddr(int64_t LineDelta, const MCSymbol *LastLabel,
    121                                 const MCSymbol *Label,
    122                                 unsigned PointerSize);
    123   void EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
    124                                  const MCSymbol *Label);
    125   void EmitCVLocDirective(unsigned FunctionId, unsigned FileNo, unsigned Line,
    126                           unsigned Column, bool PrologueEnd, bool IsStmt,
    127                           StringRef FileName) override;
    128   void EmitCVLinetableDirective(unsigned FunctionId, const MCSymbol *Begin,
    129                                 const MCSymbol *End) override;
    130   void EmitCVInlineLinetableDirective(
    131       unsigned PrimaryFunctionId, unsigned SourceFileId, unsigned SourceLineNum,
    132       const MCSymbol *FnStartSym, const MCSymbol *FnEndSym,
    133       ArrayRef<unsigned> SecondaryFunctionIds) override;
    134   void EmitCVDefRangeDirective(
    135       ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
    136       StringRef FixedSizePortion) override;
    137   void EmitCVStringTableDirective() override;
    138   void EmitCVFileChecksumsDirective() override;
    139   void EmitGPRel32Value(const MCExpr *Value) override;
    140   void EmitGPRel64Value(const MCExpr *Value) override;
    141   bool EmitRelocDirective(const MCExpr &Offset, StringRef Name,
    142                           const MCExpr *Expr, SMLoc Loc) override;
    143   using MCStreamer::emitFill;
    144   void emitFill(uint64_t NumBytes, uint8_t FillValue) override;
    145   void emitFill(const MCExpr &NumBytes, uint64_t FillValue,
    146                 SMLoc Loc = SMLoc()) override;
    147   void emitFill(const MCExpr &NumValues, int64_t Size, int64_t Expr,
    148                 SMLoc Loc = SMLoc()) override;
    149 
    150   void FinishImpl() override;
    151 
    152   /// Emit the absolute difference between two symbols if possible.
    153   ///
    154   /// Emit the absolute difference between \c Hi and \c Lo, as long as we can
    155   /// compute it.  Currently, that requires that both symbols are in the same
    156   /// data fragment.  Otherwise, do nothing and return \c false.
    157   ///
    158   /// \pre Offset of \c Hi is greater than the offset \c Lo.
    159   void emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo,
    160                               unsigned Size) override;
    161 
    162   bool mayHaveInstructions(MCSection &Sec) const override;
    163 };
    164 
    165 } // end namespace llvm
    166 
    167 #endif
    168