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"
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 MCSection *CurSectionData;
39 MCSection::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 MCSection *getCurrentSectionData() const { return CurSectionData; }
69 MCFragment *getCurrentFragment() const;
71 void insert(MCFragment *F) {
72 flushPendingLabels(F);
73 CurSectionData->getFragmentList().insert(CurInsertionPoint, F);
74 F->setParent(CurSectionData);
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();
81 bool changeSectionImpl(MCSection *Section, const MCExpr *Subsection);
83 /// If any labels have been emitted but not assigned fragments, ensure that
84 /// they get assigned, either to F if possible or to a new data fragment.
85 /// Optionally, it is also possible to provide an offset \p FOffset, which
86 /// will be used as a symbol offset within the fragment.
87 void flushPendingLabels(MCFragment *F, uint64_t FOffset = 0);
90 void visitUsedSymbol(const MCSymbol &Sym) override;
92 MCAssembler &getAssembler() { return *Assembler; }
94 /// \name MCStreamer Interface
97 void EmitLabel(MCSymbol *Symbol) override;
98 void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) override;
99 void EmitValueImpl(const MCExpr *Value, unsigned Size,
100 const SMLoc &Loc = SMLoc()) override;
101 void EmitULEB128Value(const MCExpr *Value) override;
102 void EmitSLEB128Value(const MCExpr *Value) override;
103 void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) override;
104 void ChangeSection(MCSection *Section, const MCExpr *Subsection) override;
105 void EmitInstruction(const MCInst &Inst, const MCSubtargetInfo& STI) override;
107 /// \brief Emit an instruction to a special fragment, because this instruction
108 /// can change its size during relaxation.
109 virtual void EmitInstToFragment(const MCInst &Inst, const MCSubtargetInfo &);
111 void EmitBundleAlignMode(unsigned AlignPow2) override;
112 void EmitBundleLock(bool AlignToEnd) override;
113 void EmitBundleUnlock() override;
114 void EmitBytes(StringRef Data) override;
115 void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
116 unsigned ValueSize = 1,
117 unsigned MaxBytesToEmit = 0) override;
118 void EmitCodeAlignment(unsigned ByteAlignment,
119 unsigned MaxBytesToEmit = 0) override;
120 bool EmitValueToOffset(const MCExpr *Offset, unsigned char Value) override;
121 void EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
122 unsigned Column, unsigned Flags,
123 unsigned Isa, unsigned Discriminator,
124 StringRef FileName) override;
125 void EmitDwarfAdvanceLineAddr(int64_t LineDelta, const MCSymbol *LastLabel,
126 const MCSymbol *Label,
127 unsigned PointerSize);
128 void EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
129 const MCSymbol *Label);
130 void EmitGPRel32Value(const MCExpr *Value) override;
131 void EmitGPRel64Value(const MCExpr *Value) override;
132 void EmitFill(uint64_t NumBytes, uint8_t FillValue) override;
133 void EmitZeros(uint64_t NumBytes) override;
134 void FinishImpl() override;
136 /// Emit the absolute difference between two symbols if possible.
138 /// Emit the absolute difference between \c Hi and \c Lo, as long as we can
139 /// compute it. Currently, that requires that both symbols are in the same
140 /// data fragment. Otherwise, do nothing and return \c false.
142 /// \pre Offset of \c Hi is greater than the offset \c Lo.
143 /// \return true on success.
144 bool emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo,
145 unsigned Size) override;
147 bool mayHaveInstructions(MCSection &Sec) const override;
150 } // end namespace llvm