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 MCAsmLayout; |
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 MCObjectWriter { |
35 | protected: |
36 | std::vector<const MCSymbol *> AddrsigSyms; |
37 | bool EmitAddrsigSection = false; |
38 | |
39 | MCObjectWriter() = default; |
40 | |
41 | public: |
42 | MCObjectWriter(const MCObjectWriter &) = delete; |
43 | MCObjectWriter &operator=(const MCObjectWriter &) = delete; |
44 | virtual ~MCObjectWriter(); |
45 | |
46 | /// lifetime management |
47 | virtual void reset() {} |
48 | |
49 | /// \name High-Level API |
50 | /// @{ |
51 | |
52 | /// Perform any late binding of symbols (for example, to assign symbol |
53 | /// indices for use when generating relocations). |
54 | /// |
55 | /// This routine is called by the assembler after layout and relaxation is |
56 | /// complete. |
57 | virtual void executePostLayoutBinding(MCAssembler &Asm, |
58 | const MCAsmLayout &Layout) = 0; |
59 | |
60 | /// Record a relocation entry. |
61 | /// |
62 | /// This routine is called by the assembler after layout and relaxation, and |
63 | /// post layout binding. The implementation is responsible for storing |
64 | /// information about the relocation so that it can be emitted during |
65 | /// writeObject(). |
66 | virtual void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout, |
67 | const MCFragment *Fragment, |
68 | const MCFixup &Fixup, MCValue Target, |
69 | uint64_t &FixedValue) = 0; |
70 | |
71 | /// Check whether the difference (A - B) between two symbol references is |
72 | /// fully resolved. |
73 | /// |
74 | /// Clients are not required to answer precisely and may conservatively return |
75 | /// false, even when a difference is fully resolved. |
76 | bool isSymbolRefDifferenceFullyResolved(const MCAssembler &Asm, |
77 | const MCSymbolRefExpr *A, |
78 | const MCSymbolRefExpr *B, |
79 | bool InSet) const; |
80 | |
81 | virtual bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm, |
82 | const MCSymbol &A, |
83 | const MCSymbol &B, |
84 | bool InSet) const; |
85 | |
86 | virtual bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm, |
87 | const MCSymbol &SymA, |
88 | const MCFragment &FB, |
89 | bool InSet, |
90 | bool IsPCRel) const; |
91 | |
92 | /// ELF only. Mark that we have seen GNU ABI usage (e.g. SHF_GNU_RETAIN). |
93 | virtual void markGnuAbi() {} |
94 | |
95 | /// ELF only, override the default ABIVersion in the ELF header. |
96 | virtual void setOverrideABIVersion(uint8_t ABIVersion) {} |
97 | |
98 | /// Tell the object writer to emit an address-significance table during |
99 | /// writeObject(). If this function is not called, all symbols are treated as |
100 | /// address-significant. |
101 | void emitAddrsigSection() { EmitAddrsigSection = true; } |
102 | |
103 | bool getEmitAddrsigSection() { return EmitAddrsigSection; } |
104 | |
105 | /// Record the given symbol in the address-significance table to be written |
106 | /// diring writeObject(). |
107 | void addAddrsigSymbol(const MCSymbol *Sym) { AddrsigSyms.push_back(x: Sym); } |
108 | |
109 | std::vector<const MCSymbol *> &getAddrsigSyms() { return AddrsigSyms; } |
110 | |
111 | virtual void addExceptionEntry(const MCSymbol *Symbol, const MCSymbol *Trap, |
112 | unsigned LanguageCode, unsigned ReasonCode, |
113 | unsigned FunctionSize, bool hasDebug) { |
114 | report_fatal_error(reason: "addExceptionEntry is only supported on XCOFF targets" ); |
115 | } |
116 | virtual void addCInfoSymEntry(StringRef Name, StringRef Metadata) { |
117 | report_fatal_error(reason: "addCInfoSymEntry is only supported on XCOFF targets" ); |
118 | } |
119 | /// Write the object file and returns the number of bytes written. |
120 | /// |
121 | /// This routine is called by the assembler after layout and relaxation is |
122 | /// complete, fixups have been evaluated and applied, and relocations |
123 | /// generated. |
124 | virtual uint64_t writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) = 0; |
125 | |
126 | /// @} |
127 | }; |
128 | |
129 | /// Base class for classes that define behaviour that is specific to both the |
130 | /// target and the object format. |
131 | class MCObjectTargetWriter { |
132 | public: |
133 | virtual ~MCObjectTargetWriter() = default; |
134 | virtual Triple::ObjectFormatType getFormat() const = 0; |
135 | }; |
136 | |
137 | } // end namespace llvm |
138 | |
139 | #endif // LLVM_MC_MCOBJECTWRITER_H |
140 | |