1 //===- llvm/MC/MCObjectWriter.h - Object File Writer 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_MCOBJECTWRITER_H 10 #define LLVM_MC_MCOBJECTWRITER_H 11 12 #include "llvm/MC/MCSymbol.h" 13 #include "llvm/Support/Compiler.h" 14 #include "llvm/TargetParser/Triple.h" 15 #include <cstdint> 16 17 namespace llvm { 18 19 class MCAssembler; 20 class MCFixup; 21 class MCFragment; 22 class MCSymbol; 23 class MCSymbolRefExpr; 24 class MCValue; 25 26 /// Defines the object file and target independent interfaces used by the 27 /// assembler backend to write native file format object files. 28 /// 29 /// The object writer contains a few callbacks used by the assembler to allow 30 /// the object writer to modify the assembler data structures at appropriate 31 /// points. Once assembly is complete, the object writer is given the 32 /// MCAssembler instance, which contains all the symbol and section data which 33 /// should be emitted as part of writeObject(). 34 class LLVM_ABI MCObjectWriter { 35 protected: 36 MCAssembler *Asm = nullptr; 37 /// List of declared file names 38 SmallVector<std::pair<std::string, size_t>, 0> FileNames; 39 // XCOFF specific: Optional compiler version. 40 std::string CompilerVersion; 41 std::vector<const MCSymbol *> AddrsigSyms; 42 bool EmitAddrsigSection = false; 43 bool SubsectionsViaSymbols = false; 44 45 struct CGProfileEntry { 46 const MCSymbolRefExpr *From; 47 const MCSymbolRefExpr *To; 48 uint64_t Count; 49 }; 50 SmallVector<CGProfileEntry, 0> CGProfile; 51 52 MCObjectWriter() = default; 53 54 public: 55 MCObjectWriter(const MCObjectWriter &) = delete; 56 MCObjectWriter &operator=(const MCObjectWriter &) = delete; 57 virtual ~MCObjectWriter(); 58 setAssembler(MCAssembler * A)59 virtual void setAssembler(MCAssembler *A) { Asm = A; } 60 61 MCContext &getContext() const; 62 63 /// lifetime management 64 virtual void reset(); 65 66 /// \name High-Level API 67 /// @{ 68 69 /// Perform any late binding of symbols (for example, to assign symbol 70 /// indices for use when generating relocations). 71 /// 72 /// This routine is called by the assembler after layout and relaxation is 73 /// complete. executePostLayoutBinding()74 virtual void executePostLayoutBinding() {} 75 76 /// Record a relocation entry. 77 /// 78 /// This routine is called by the assembler after layout and relaxation, and 79 /// post layout binding. The implementation is responsible for storing 80 /// information about the relocation so that it can be emitted during 81 /// writeObject(). 82 virtual void recordRelocation(const MCFragment &F, const MCFixup &Fixup, 83 MCValue Target, uint64_t &FixedValue); 84 85 /// Check whether the difference (A - B) between two symbol references is 86 /// fully resolved. 87 /// 88 /// Clients are not required to answer precisely and may conservatively return 89 /// false, even when a difference is fully resolved. 90 bool isSymbolRefDifferenceFullyResolved(const MCSymbol &A, const MCSymbol &B, 91 bool InSet) const; 92 93 virtual bool isSymbolRefDifferenceFullyResolvedImpl(const MCSymbol &SymA, 94 const MCFragment &FB, 95 bool InSet, 96 bool IsPCRel) const; 97 getFileNames()98 MutableArrayRef<std::pair<std::string, size_t>> getFileNames() { 99 return FileNames; 100 } 101 void addFileName(StringRef FileName); setCompilerVersion(StringRef CompilerVers)102 void setCompilerVersion(StringRef CompilerVers) { 103 CompilerVersion = CompilerVers; 104 } 105 106 /// Tell the object writer to emit an address-significance table during 107 /// writeObject(). If this function is not called, all symbols are treated as 108 /// address-significant. emitAddrsigSection()109 void emitAddrsigSection() { EmitAddrsigSection = true; } 110 getEmitAddrsigSection()111 bool getEmitAddrsigSection() { return EmitAddrsigSection; } 112 113 /// Record the given symbol in the address-significance table to be written 114 /// diring writeObject(). addAddrsigSymbol(const MCSymbol * Sym)115 void addAddrsigSymbol(const MCSymbol *Sym) { AddrsigSyms.push_back(Sym); } 116 getAddrsigSyms()117 std::vector<const MCSymbol *> &getAddrsigSyms() { return AddrsigSyms; } getCGProfile()118 SmallVector<CGProfileEntry, 0> &getCGProfile() { return CGProfile; } 119 120 // Mach-O specific: Whether .subsections_via_symbols is enabled. getSubsectionsViaSymbols()121 bool getSubsectionsViaSymbols() const { return SubsectionsViaSymbols; } setSubsectionsViaSymbols(bool Value)122 void setSubsectionsViaSymbols(bool Value) { SubsectionsViaSymbols = Value; } 123 124 /// Write the object file and returns the number of bytes written. 125 /// 126 /// This routine is called by the assembler after layout and relaxation is 127 /// complete, fixups have been evaluated and applied, and relocations 128 /// generated. 129 virtual uint64_t writeObject() = 0; 130 131 /// @} 132 }; 133 134 /// Base class for classes that define behaviour that is specific to both the 135 /// target and the object format. 136 class MCObjectTargetWriter { 137 public: 138 virtual ~MCObjectTargetWriter() = default; setAssembler(MCAssembler * A)139 void setAssembler(MCAssembler *A) { Asm = A; } 140 virtual Triple::ObjectFormatType getFormat() const = 0; 141 142 protected: 143 LLVM_ABI MCContext &getContext() const; 144 LLVM_ABI void reportError(SMLoc L, const Twine &Msg) const; 145 146 MCAssembler *Asm = nullptr; 147 }; 148 149 } // end namespace llvm 150 151 #endif // LLVM_MC_MCOBJECTWRITER_H 152