1 //===- MCObjectStreamer.h - MCStreamer Object File Interface ----*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef LLVM_MC_MCOBJECTSTREAMER_H 10 #define LLVM_MC_MCOBJECTSTREAMER_H 11 12 #include "llvm/ADT/SmallVector.h" 13 #include "llvm/MC/MCAssembler.h" 14 #include "llvm/MC/MCSection.h" 15 #include "llvm/MC/MCStreamer.h" 16 17 namespace llvm { 18 class MCAssembler; 19 class MCCodeEmitter; 20 class MCSubtargetInfo; 21 class MCExpr; 22 class MCFragment; 23 class MCDataFragment; 24 class MCAsmBackend; 25 class raw_ostream; 26 class raw_pwrite_stream; 27 28 /// Streaming object file generation interface. 29 /// 30 /// This class provides an implementation of the MCStreamer interface which is 31 /// suitable for use with the assembler backend. Specific object file formats 32 /// are expected to subclass this interface to implement directives specific 33 /// to that file format or custom semantics expected by the object writer 34 /// implementation. 35 class MCObjectStreamer : public MCStreamer { 36 std::unique_ptr<MCAssembler> Assembler; 37 MCSection::iterator CurInsertionPoint; 38 bool EmitEHFrame; 39 bool EmitDebugFrame; 40 SmallVector<MCSymbol *, 2> PendingLabels; 41 struct PendingMCFixup { 42 const MCSymbol *Sym; 43 MCFixup Fixup; 44 MCDataFragment *DF; 45 PendingMCFixup(const MCSymbol *McSym, MCDataFragment *F, MCFixup McFixup) 46 : Sym(McSym), Fixup(McFixup), DF(F) {} 47 }; 48 SmallVector<PendingMCFixup, 2> PendingFixups; 49 50 virtual void EmitInstToData(const MCInst &Inst, const MCSubtargetInfo&) = 0; 51 void EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) override; 52 void EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) override; 53 MCSymbol *EmitCFILabel() override; 54 void EmitInstructionImpl(const MCInst &Inst, const MCSubtargetInfo &STI); 55 void resolvePendingFixups(); 56 57 protected: 58 MCObjectStreamer(MCContext &Context, std::unique_ptr<MCAsmBackend> TAB, 59 std::unique_ptr<MCObjectWriter> OW, 60 std::unique_ptr<MCCodeEmitter> Emitter); 61 ~MCObjectStreamer(); 62 63 public: 64 /// state management 65 void reset() override; 66 67 /// Object streamers require the integrated assembler. 68 bool isIntegratedAssemblerRequired() const override { return true; } 69 70 void EmitFrames(MCAsmBackend *MAB); 71 void EmitCFISections(bool EH, bool Debug) override; 72 73 MCFragment *getCurrentFragment() const; 74 75 void insert(MCFragment *F) { 76 flushPendingLabels(F); 77 MCSection *CurSection = getCurrentSectionOnly(); 78 CurSection->getFragmentList().insert(CurInsertionPoint, F); 79 F->setParent(CurSection); 80 } 81 82 /// Get a data fragment to write into, creating a new one if the current 83 /// fragment is not a data fragment. 84 /// Optionally a \p STI can be passed in so that a new fragment is created 85 /// if the Subtarget differs from the current fragment. 86 MCDataFragment *getOrCreateDataFragment(const MCSubtargetInfo* STI = nullptr); 87 MCPaddingFragment *getOrCreatePaddingFragment(); 88 89 protected: 90 bool changeSectionImpl(MCSection *Section, const MCExpr *Subsection); 91 92 /// If any labels have been emitted but not assigned fragments, ensure that 93 /// they get assigned, either to F if possible or to a new data fragment. 94 /// Optionally, it is also possible to provide an offset \p FOffset, which 95 /// will be used as a symbol offset within the fragment. 96 void flushPendingLabels(MCFragment *F, uint64_t FOffset = 0); 97 98 public: 99 void visitUsedSymbol(const MCSymbol &Sym) override; 100 101 /// Create a dummy fragment to assign any pending labels. 102 void flushPendingLabels() { flushPendingLabels(nullptr); } 103 104 MCAssembler &getAssembler() { return *Assembler; } 105 MCAssembler *getAssemblerPtr() override; 106 /// \name MCStreamer Interface 107 /// @{ 108 109 void EmitLabel(MCSymbol *Symbol, SMLoc Loc = SMLoc()) override; 110 virtual void EmitLabel(MCSymbol *Symbol, SMLoc Loc, MCFragment *F); 111 void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) override; 112 void EmitValueImpl(const MCExpr *Value, unsigned Size, 113 SMLoc Loc = SMLoc()) override; 114 void EmitULEB128Value(const MCExpr *Value) override; 115 void EmitSLEB128Value(const MCExpr *Value) override; 116 void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) override; 117 void ChangeSection(MCSection *Section, const MCExpr *Subsection) override; 118 void EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI) override; 119 120 /// Emit an instruction to a special fragment, because this instruction 121 /// can change its size during relaxation. 122 virtual void EmitInstToFragment(const MCInst &Inst, const MCSubtargetInfo &); 123 124 void EmitBundleAlignMode(unsigned AlignPow2) override; 125 void EmitBundleLock(bool AlignToEnd) override; 126 void EmitBundleUnlock() override; 127 void EmitBytes(StringRef Data) override; 128 void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0, 129 unsigned ValueSize = 1, 130 unsigned MaxBytesToEmit = 0) override; 131 void EmitCodeAlignment(unsigned ByteAlignment, 132 unsigned MaxBytesToEmit = 0) override; 133 void emitValueToOffset(const MCExpr *Offset, unsigned char Value, 134 SMLoc Loc) override; 135 void 136 EmitCodePaddingBasicBlockStart(const MCCodePaddingContext &Context) override; 137 void 138 EmitCodePaddingBasicBlockEnd(const MCCodePaddingContext &Context) override; 139 void EmitDwarfLocDirective(unsigned FileNo, unsigned Line, 140 unsigned Column, unsigned Flags, 141 unsigned Isa, unsigned Discriminator, 142 StringRef FileName) override; 143 void EmitDwarfAdvanceLineAddr(int64_t LineDelta, const MCSymbol *LastLabel, 144 const MCSymbol *Label, 145 unsigned PointerSize); 146 void EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel, 147 const MCSymbol *Label); 148 void EmitCVLocDirective(unsigned FunctionId, unsigned FileNo, unsigned Line, 149 unsigned Column, bool PrologueEnd, bool IsStmt, 150 StringRef FileName, SMLoc Loc) override; 151 void EmitCVLinetableDirective(unsigned FunctionId, const MCSymbol *Begin, 152 const MCSymbol *End) override; 153 void EmitCVInlineLinetableDirective(unsigned PrimaryFunctionId, 154 unsigned SourceFileId, 155 unsigned SourceLineNum, 156 const MCSymbol *FnStartSym, 157 const MCSymbol *FnEndSym) override; 158 void EmitCVDefRangeDirective( 159 ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges, 160 StringRef FixedSizePortion) override; 161 void EmitCVStringTableDirective() override; 162 void EmitCVFileChecksumsDirective() override; 163 void EmitCVFileChecksumOffsetDirective(unsigned FileNo) override; 164 void EmitDTPRel32Value(const MCExpr *Value) override; 165 void EmitDTPRel64Value(const MCExpr *Value) override; 166 void EmitTPRel32Value(const MCExpr *Value) override; 167 void EmitTPRel64Value(const MCExpr *Value) override; 168 void EmitGPRel32Value(const MCExpr *Value) override; 169 void EmitGPRel64Value(const MCExpr *Value) override; 170 bool EmitRelocDirective(const MCExpr &Offset, StringRef Name, 171 const MCExpr *Expr, SMLoc Loc, 172 const MCSubtargetInfo &STI) override; 173 using MCStreamer::emitFill; 174 void emitFill(const MCExpr &NumBytes, uint64_t FillValue, 175 SMLoc Loc = SMLoc()) override; 176 void emitFill(const MCExpr &NumValues, int64_t Size, int64_t Expr, 177 SMLoc Loc = SMLoc()) override; 178 void EmitFileDirective(StringRef Filename) override; 179 180 void EmitAddrsig() override; 181 void EmitAddrsigSym(const MCSymbol *Sym) override; 182 183 void FinishImpl() override; 184 185 /// Emit the absolute difference between two symbols if possible. 186 /// 187 /// Emit the absolute difference between \c Hi and \c Lo, as long as we can 188 /// compute it. Currently, that requires that both symbols are in the same 189 /// data fragment and that the target has not specified that diff expressions 190 /// require relocations to be emitted. Otherwise, do nothing and return 191 /// \c false. 192 /// 193 /// \pre Offset of \c Hi is greater than the offset \c Lo. 194 void emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo, 195 unsigned Size) override; 196 197 void emitAbsoluteSymbolDiffAsULEB128(const MCSymbol *Hi, 198 const MCSymbol *Lo) override; 199 200 bool mayHaveInstructions(MCSection &Sec) const override; 201 }; 202 203 } // end namespace llvm 204 205 #endif 206