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/MCStreamer.h"
16 
17 namespace llvm {
18 class MCAssembler;
19 class MCCodeEmitter;
20 class MCSectionData;
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   MCSectionData *CurSectionData;
39   MCSectionData::iterator CurInsertionPoint;
40   bool EmitEHFrame;
41   bool EmitDebugFrame;
42   SmallVector<MCSymbolData *, 2> PendingLabels;
43 
44   virtual void EmitInstToData(const MCInst &Inst, const MCSubtargetInfo&) = 0;
45   void EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) override;
46   void EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) override;
47 
48 protected:
49   MCObjectStreamer(MCContext &Context, MCAsmBackend &TAB, raw_pwrite_stream &OS,
50                    MCCodeEmitter *Emitter);
51   ~MCObjectStreamer() override;
52 
53 public:
54   /// state management
55   void reset() override;
56 
57   /// Object streamers require the integrated assembler.
isIntegratedAssemblerRequired()58   bool isIntegratedAssemblerRequired() const override { return true; }
59 
getOrCreateSymbolData(const MCSymbol * Symbol)60   MCSymbolData &getOrCreateSymbolData(const MCSymbol *Symbol) {
61     return getAssembler().getOrCreateSymbolData(*Symbol);
62   }
63   void EmitFrames(MCAsmBackend *MAB);
64   void EmitCFISections(bool EH, bool Debug) override;
65 
66 protected:
getCurrentSectionData()67   MCSectionData *getCurrentSectionData() const {
68     return CurSectionData;
69   }
70 
71   MCFragment *getCurrentFragment() const;
72 
insert(MCFragment * F)73   void insert(MCFragment *F) {
74     flushPendingLabels(F);
75     CurSectionData->getFragmentList().insert(CurInsertionPoint, F);
76     F->setParent(CurSectionData);
77   }
78 
79   /// Get a data fragment to write into, creating a new one if the current
80   /// fragment is not a data fragment.
81   MCDataFragment *getOrCreateDataFragment();
82 
83   bool changeSectionImpl(const MCSection *Section, const MCExpr *Subsection);
84 
85   /// If any labels have been emitted but not assigned fragments, ensure that
86   /// they get assigned, either to F if possible or to a new data fragment.
87   /// Optionally, it is also possible to provide an offset \p FOffset, which
88   /// will be used as a symbol offset within the fragment.
89   void flushPendingLabels(MCFragment *F, uint64_t FOffset = 0);
90 
91 public:
92   void visitUsedSymbol(const MCSymbol &Sym) override;
93 
getAssembler()94   MCAssembler &getAssembler() { return *Assembler; }
95 
96   /// @name MCStreamer Interface
97   /// @{
98 
99   void EmitLabel(MCSymbol *Symbol) override;
100   void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) override;
101   void EmitValueImpl(const MCExpr *Value, unsigned Size,
102                      const SMLoc &Loc = SMLoc()) override;
103   void EmitULEB128Value(const MCExpr *Value) override;
104   void EmitSLEB128Value(const MCExpr *Value) override;
105   void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) override;
106   void ChangeSection(const MCSection *Section,
107                      const MCExpr *Subsection) override;
108   void EmitInstruction(const MCInst &Inst, const MCSubtargetInfo& STI) override;
109 
110   /// \brief Emit an instruction to a special fragment, because this instruction
111   /// can change its size during relaxation.
112   virtual void EmitInstToFragment(const MCInst &Inst, const MCSubtargetInfo &);
113 
114   void EmitBundleAlignMode(unsigned AlignPow2) override;
115   void EmitBundleLock(bool AlignToEnd) override;
116   void EmitBundleUnlock() override;
117   void EmitBytes(StringRef Data) override;
118   void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
119                             unsigned ValueSize = 1,
120                             unsigned MaxBytesToEmit = 0) override;
121   void EmitCodeAlignment(unsigned ByteAlignment,
122                          unsigned MaxBytesToEmit = 0) override;
123   bool EmitValueToOffset(const MCExpr *Offset, unsigned char Value) override;
124   void EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
125                              unsigned Column, unsigned Flags,
126                              unsigned Isa, unsigned Discriminator,
127                              StringRef FileName) override;
128   void EmitDwarfAdvanceLineAddr(int64_t LineDelta, const MCSymbol *LastLabel,
129                                 const MCSymbol *Label,
130                                 unsigned PointerSize);
131   void EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
132                                  const MCSymbol *Label);
133   void EmitGPRel32Value(const MCExpr *Value) override;
134   void EmitGPRel64Value(const MCExpr *Value) override;
135   void EmitFill(uint64_t NumBytes, uint8_t FillValue) override;
136   void EmitZeros(uint64_t NumBytes) override;
137   void FinishImpl() override;
138 
mayHaveInstructions()139   bool mayHaveInstructions() const override {
140     return getCurrentSectionData()->hasInstructions();
141   }
142 };
143 
144 } // end namespace llvm
145 
146 #endif
147