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