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/MCStreamer.h"
21 class MCSubtargetInfo;
27 class raw_pwrite_stream;
29 /// \brief Streaming object file generation interface.
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
36 class MCObjectStreamer : public MCStreamer {
37 MCAssembler *Assembler;
38 MCSectionData *CurSectionData;
39 MCSectionData::iterator CurInsertionPoint;
42 SmallVector<MCSymbolData *, 2> PendingLabels;
44 virtual void EmitInstToData(const MCInst &Inst, const MCSubtargetInfo&) = 0;
45 void EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) override;
46 void EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) override;
49 MCObjectStreamer(MCContext &Context, MCAsmBackend &TAB, raw_pwrite_stream &OS,
50 MCCodeEmitter *Emitter);
51 ~MCObjectStreamer() override;
55 void reset() override;
57 /// Object streamers require the integrated assembler.
58 bool isIntegratedAssemblerRequired() const override { return true; }
60 MCSymbolData &getOrCreateSymbolData(const MCSymbol *Symbol) {
61 return getAssembler().getOrCreateSymbolData(*Symbol);
63 void EmitFrames(MCAsmBackend *MAB);
64 void EmitCFISections(bool EH, bool Debug) override;
67 MCSectionData *getCurrentSectionData() const {
68 return CurSectionData;
71 MCFragment *getCurrentFragment() const;
73 void insert(MCFragment *F) {
74 flushPendingLabels(F);
75 CurSectionData->getFragmentList().insert(CurInsertionPoint, F);
76 F->setParent(CurSectionData);
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();
83 bool changeSectionImpl(MCSection *Section, const MCExpr *Subsection);
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);
92 void visitUsedSymbol(const MCSymbol &Sym) override;
94 MCAssembler &getAssembler() { return *Assembler; }
96 /// \name MCStreamer Interface
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(MCSection *Section, const MCExpr *Subsection) override;
107 void EmitInstruction(const MCInst &Inst, const MCSubtargetInfo& STI) override;
109 /// \brief Emit an instruction to a special fragment, because this instruction
110 /// can change its size during relaxation.
111 virtual void EmitInstToFragment(const MCInst &Inst, const MCSubtargetInfo &);
113 void EmitBundleAlignMode(unsigned AlignPow2) override;
114 void EmitBundleLock(bool AlignToEnd) override;
115 void EmitBundleUnlock() override;
116 void EmitBytes(StringRef Data) override;
117 void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
118 unsigned ValueSize = 1,
119 unsigned MaxBytesToEmit = 0) override;
120 void EmitCodeAlignment(unsigned ByteAlignment,
121 unsigned MaxBytesToEmit = 0) override;
122 bool EmitValueToOffset(const MCExpr *Offset, unsigned char Value) override;
123 void EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
124 unsigned Column, unsigned Flags,
125 unsigned Isa, unsigned Discriminator,
126 StringRef FileName) override;
127 void EmitDwarfAdvanceLineAddr(int64_t LineDelta, const MCSymbol *LastLabel,
128 const MCSymbol *Label,
129 unsigned PointerSize);
130 void EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
131 const MCSymbol *Label);
132 void EmitGPRel32Value(const MCExpr *Value) override;
133 void EmitGPRel64Value(const MCExpr *Value) override;
134 void EmitFill(uint64_t NumBytes, uint8_t FillValue) override;
135 void EmitZeros(uint64_t NumBytes) override;
136 void FinishImpl() override;
138 /// Emit the absolute difference between two symbols if possible.
140 /// Emit the absolute difference between \c Hi and \c Lo, as long as we can
141 /// compute it. Currently, that requires that both symbols are in the same
142 /// data fragment. Otherwise, do nothing and return \c false.
144 /// \pre Offset of \c Hi is greater than the offset \c Lo.
145 /// \return true on success.
146 bool emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo,
147 unsigned Size) override;
149 bool mayHaveInstructions(MCSection &Sec) const override {
150 return Assembler->getOrCreateSectionData(Sec).hasInstructions();
154 } // end namespace llvm