1 //===- MCObjectStreamer.h - MCStreamer Object File Interface ----*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #ifndef LLVM_MC_MCOBJECTSTREAMER_H
11 #define LLVM_MC_MCOBJECTSTREAMER_H
13 #include "llvm/ADT/SmallVector.h"
14 #include "llvm/MC/MCAssembler.h"
15 #include "llvm/MC/MCSection.h"
16 #include "llvm/MC/MCStreamer.h"
22 class MCSubtargetInfo;
28 class raw_pwrite_stream;
30 /// \brief Streaming object file generation interface.
32 /// This class provides an implementation of the MCStreamer interface which is
33 /// suitable for use with the assembler backend. Specific object file formats
34 /// are expected to subclass this interface to implement directives specific
35 /// to that file format or custom semantics expected by the object writer
37 class MCObjectStreamer : public MCStreamer {
38 MCAssembler *Assembler;
39 MCSectionData *CurSectionData;
40 MCSectionData::iterator CurInsertionPoint;
43 SmallVector<MCSymbolData *, 2> PendingLabels;
45 virtual void EmitInstToData(const MCInst &Inst, const MCSubtargetInfo&) = 0;
46 void EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) override;
47 void EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) override;
50 MCObjectStreamer(MCContext &Context, MCAsmBackend &TAB, raw_pwrite_stream &OS,
51 MCCodeEmitter *Emitter);
52 ~MCObjectStreamer() override;
56 void reset() override;
58 /// Object streamers require the integrated assembler.
59 bool isIntegratedAssemblerRequired() const override { return true; }
61 MCSymbolData &getOrCreateSymbolData(const MCSymbol *Symbol) {
62 return getAssembler().getOrCreateSymbolData(*Symbol);
64 void EmitFrames(MCAsmBackend *MAB);
65 void EmitCFISections(bool EH, bool Debug) override;
68 MCSectionData *getCurrentSectionData() const {
69 return CurSectionData;
72 MCFragment *getCurrentFragment() const;
74 void insert(MCFragment *F) {
75 flushPendingLabels(F);
76 CurSectionData->getFragmentList().insert(CurInsertionPoint, F);
77 F->setParent(&CurSectionData->getSection());
80 /// Get a data fragment to write into, creating a new one if the current
81 /// fragment is not a data fragment.
82 MCDataFragment *getOrCreateDataFragment();
84 bool changeSectionImpl(MCSection *Section, const MCExpr *Subsection);
86 /// If any labels have been emitted but not assigned fragments, ensure that
87 /// they get assigned, either to F if possible or to a new data fragment.
88 /// Optionally, it is also possible to provide an offset \p FOffset, which
89 /// will be used as a symbol offset within the fragment.
90 void flushPendingLabels(MCFragment *F, uint64_t FOffset = 0);
93 void visitUsedSymbol(const MCSymbol &Sym) override;
95 MCAssembler &getAssembler() { return *Assembler; }
97 /// \name MCStreamer Interface
100 void EmitLabel(MCSymbol *Symbol) override;
101 void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) override;
102 void EmitValueImpl(const MCExpr *Value, unsigned Size,
103 const SMLoc &Loc = SMLoc()) override;
104 void EmitULEB128Value(const MCExpr *Value) override;
105 void EmitSLEB128Value(const MCExpr *Value) override;
106 void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) override;
107 void ChangeSection(MCSection *Section, const MCExpr *Subsection) override;
108 void EmitInstruction(const MCInst &Inst, const MCSubtargetInfo& STI) override;
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 &);
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;
139 /// Emit the absolute difference between two symbols if possible.
141 /// Emit the absolute difference between \c Hi and \c Lo, as long as we can
142 /// compute it. Currently, that requires that both symbols are in the same
143 /// data fragment. Otherwise, do nothing and return \c false.
145 /// \pre Offset of \c Hi is greater than the offset \c Lo.
146 /// \return true on success.
147 bool emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo,
148 unsigned Size) override;
150 bool mayHaveInstructions(MCSection &Sec) const override;
153 } // end namespace llvm