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/SetVector.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" 17 18 namespace llvm { 19 class MCAssembler; 20 class MCCodeEmitter; 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 /// 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 std::unique_ptr<MCAssembler> Assembler; 38 MCSection::iterator CurInsertionPoint; 39 bool EmitEHFrame; 40 bool EmitDebugFrame; 41 SmallVector<MCSymbol *, 2> PendingLabels; 42 SmallSetVector<MCSection *, 4> PendingLabelSections; 43 unsigned CurSubsectionIdx; 44 struct PendingMCFixup { 45 const MCSymbol *Sym; 46 MCFixup Fixup; 47 MCDataFragment *DF; 48 PendingMCFixup(const MCSymbol *McSym, MCDataFragment *F, MCFixup McFixup) 49 : Sym(McSym), Fixup(McFixup), DF(F) {} 50 }; 51 SmallVector<PendingMCFixup, 2> PendingFixups; 52 53 struct PendingAssignment { 54 MCSymbol *Symbol; 55 const MCExpr *Value; 56 }; 57 58 /// A list of conditional assignments we may need to emit if the target 59 /// symbol is later emitted. 60 DenseMap<const MCSymbol *, SmallVector<PendingAssignment, 1>> 61 pendingAssignments; 62 63 virtual void emitInstToData(const MCInst &Inst, const MCSubtargetInfo&) = 0; 64 void emitCFIStartProcImpl(MCDwarfFrameInfo &Frame) override; 65 void emitCFIEndProcImpl(MCDwarfFrameInfo &Frame) override; 66 MCSymbol *emitCFILabel() override; 67 void emitInstructionImpl(const MCInst &Inst, const MCSubtargetInfo &STI); 68 void resolvePendingFixups(); 69 70 protected: 71 MCObjectStreamer(MCContext &Context, std::unique_ptr<MCAsmBackend> TAB, 72 std::unique_ptr<MCObjectWriter> OW, 73 std::unique_ptr<MCCodeEmitter> Emitter); 74 ~MCObjectStreamer(); 75 76 public: 77 /// state management 78 void reset() override; 79 80 /// Object streamers require the integrated assembler. 81 bool isIntegratedAssemblerRequired() const override { return true; } 82 83 void emitFrames(MCAsmBackend *MAB); 84 void emitCFISections(bool EH, bool Debug) override; 85 86 MCFragment *getCurrentFragment() const; 87 88 void insert(MCFragment *F) { 89 flushPendingLabels(F); 90 MCSection *CurSection = getCurrentSectionOnly(); 91 CurSection->getFragmentList().insert(CurInsertionPoint, F); 92 F->setParent(CurSection); 93 } 94 95 /// Get a data fragment to write into, creating a new one if the current 96 /// fragment is not a data fragment. 97 /// Optionally a \p STI can be passed in so that a new fragment is created 98 /// if the Subtarget differs from the current fragment. 99 MCDataFragment *getOrCreateDataFragment(const MCSubtargetInfo* STI = nullptr); 100 101 protected: 102 bool changeSectionImpl(MCSection *Section, const MCExpr *Subsection); 103 104 /// Assign a label to the current Section and Subsection even though a 105 /// fragment is not yet present. Use flushPendingLabels(F) to associate 106 /// a fragment with this label. 107 void addPendingLabel(MCSymbol* label); 108 109 /// If any labels have been emitted but not assigned fragments in the current 110 /// Section and Subsection, ensure that they get assigned, either to fragment 111 /// F if possible or to a new data fragment. Optionally, one can provide an 112 /// offset \p FOffset as a symbol offset within the fragment. 113 void flushPendingLabels(MCFragment *F, uint64_t FOffset = 0); 114 115 public: 116 void visitUsedSymbol(const MCSymbol &Sym) override; 117 118 /// Create a data fragment for any pending labels across all Sections 119 /// and Subsections. 120 void flushPendingLabels(); 121 122 MCAssembler &getAssembler() { return *Assembler; } 123 MCAssembler *getAssemblerPtr() override; 124 /// \name MCStreamer Interface 125 /// @{ 126 127 void emitLabel(MCSymbol *Symbol, SMLoc Loc = SMLoc()) override; 128 virtual void emitLabelAtPos(MCSymbol *Symbol, SMLoc Loc, MCFragment *F, 129 uint64_t Offset); 130 void emitAssignment(MCSymbol *Symbol, const MCExpr *Value) override; 131 void emitConditionalAssignment(MCSymbol *Symbol, 132 const MCExpr *Value) override; 133 void emitValueImpl(const MCExpr *Value, unsigned Size, 134 SMLoc Loc = SMLoc()) override; 135 void emitULEB128Value(const MCExpr *Value) override; 136 void emitSLEB128Value(const MCExpr *Value) override; 137 void emitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) override; 138 void changeSection(MCSection *Section, const MCExpr *Subsection) override; 139 void emitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI) override; 140 141 /// Emit an instruction to a special fragment, because this instruction 142 /// can change its size during relaxation. 143 virtual void emitInstToFragment(const MCInst &Inst, const MCSubtargetInfo &); 144 145 void emitBundleAlignMode(unsigned AlignPow2) override; 146 void emitBundleLock(bool AlignToEnd) override; 147 void emitBundleUnlock() override; 148 void emitBytes(StringRef Data) override; 149 void emitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0, 150 unsigned ValueSize = 1, 151 unsigned MaxBytesToEmit = 0) override; 152 void emitCodeAlignment(unsigned ByteAlignment, const MCSubtargetInfo *STI, 153 unsigned MaxBytesToEmit = 0) override; 154 void emitValueToOffset(const MCExpr *Offset, unsigned char Value, 155 SMLoc Loc) override; 156 void emitDwarfLocDirective(unsigned FileNo, unsigned Line, unsigned Column, 157 unsigned Flags, unsigned Isa, 158 unsigned Discriminator, 159 StringRef FileName) override; 160 void emitDwarfAdvanceLineAddr(int64_t LineDelta, const MCSymbol *LastLabel, 161 const MCSymbol *Label, 162 unsigned PointerSize) override; 163 void emitDwarfLineEndEntry(MCSection *Section, MCSymbol *LastLabel) override; 164 void emitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel, 165 const MCSymbol *Label); 166 void emitCVLocDirective(unsigned FunctionId, unsigned FileNo, unsigned Line, 167 unsigned Column, bool PrologueEnd, bool IsStmt, 168 StringRef FileName, SMLoc Loc) override; 169 void emitCVLinetableDirective(unsigned FunctionId, const MCSymbol *Begin, 170 const MCSymbol *End) override; 171 void emitCVInlineLinetableDirective(unsigned PrimaryFunctionId, 172 unsigned SourceFileId, 173 unsigned SourceLineNum, 174 const MCSymbol *FnStartSym, 175 const MCSymbol *FnEndSym) override; 176 void emitCVDefRangeDirective( 177 ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges, 178 StringRef FixedSizePortion) override; 179 void emitCVStringTableDirective() override; 180 void emitCVFileChecksumsDirective() override; 181 void emitCVFileChecksumOffsetDirective(unsigned FileNo) override; 182 void emitDTPRel32Value(const MCExpr *Value) override; 183 void emitDTPRel64Value(const MCExpr *Value) override; 184 void emitTPRel32Value(const MCExpr *Value) override; 185 void emitTPRel64Value(const MCExpr *Value) override; 186 void emitGPRel32Value(const MCExpr *Value) override; 187 void emitGPRel64Value(const MCExpr *Value) override; 188 Optional<std::pair<bool, std::string>> 189 emitRelocDirective(const MCExpr &Offset, StringRef Name, const MCExpr *Expr, 190 SMLoc Loc, const MCSubtargetInfo &STI) override; 191 using MCStreamer::emitFill; 192 void emitFill(const MCExpr &NumBytes, uint64_t FillValue, 193 SMLoc Loc = SMLoc()) override; 194 void emitFill(const MCExpr &NumValues, int64_t Size, int64_t Expr, 195 SMLoc Loc = SMLoc()) override; 196 void emitNops(int64_t NumBytes, int64_t ControlledNopLength, SMLoc Loc, 197 const MCSubtargetInfo &STI) override; 198 void emitFileDirective(StringRef Filename) override; 199 void emitFileDirective(StringRef Filename, StringRef CompilerVerion, 200 StringRef TimeStamp, StringRef Description) override; 201 202 void emitAddrsig() override; 203 void emitAddrsigSym(const MCSymbol *Sym) override; 204 205 void finishImpl() override; 206 207 /// Emit the absolute difference between two symbols if possible. 208 /// 209 /// Emit the absolute difference between \c Hi and \c Lo, as long as we can 210 /// compute it. Currently, that requires that both symbols are in the same 211 /// data fragment and that the target has not specified that diff expressions 212 /// require relocations to be emitted. Otherwise, do nothing and return 213 /// \c false. 214 /// 215 /// \pre Offset of \c Hi is greater than the offset \c Lo. 216 void emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo, 217 unsigned Size) override; 218 219 void emitAbsoluteSymbolDiffAsULEB128(const MCSymbol *Hi, 220 const MCSymbol *Lo) override; 221 222 bool mayHaveInstructions(MCSection &Sec) const override; 223 224 /// Emits pending conditional assignments that depend on \p Symbol 225 /// being emitted. 226 void emitPendingAssignments(MCSymbol *Symbol); 227 }; 228 229 } // end namespace llvm 230 231 #endif 232