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
16namespace llvm {
17
18class MCAssembler;
19class MCFixup;
20class MCFragment;
21class MCSymbol;
22class MCSymbolRefExpr;
23class 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().
33class MCObjectWriter {
34protected:
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
52public:
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.
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
96 MutableArrayRef<std::pair<std::string, size_t>> getFileNames() {
97 return FileNames;
98 }
99 void addFileName(MCAssembler &Asm, StringRef FileName);
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.
107 void emitAddrsigSection() { EmitAddrsigSection = true; }
108
109 bool getEmitAddrsigSection() { return EmitAddrsigSection; }
110
111 /// Record the given symbol in the address-significance table to be written
112 /// diring writeObject().
113 void addAddrsigSymbol(const MCSymbol *Sym) { AddrsigSyms.push_back(x: Sym); }
114
115 std::vector<const MCSymbol *> &getAddrsigSyms() { return AddrsigSyms; }
116 SmallVector<CGProfileEntry, 0> &getCGProfile() { return CGProfile; }
117
118 // Mach-O specific: Whether .subsections_via_symbols is enabled.
119 bool getSubsectionsViaSymbols() const { return SubsectionsViaSymbols; }
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.
134class MCObjectTargetWriter {
135public:
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