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1 : //===- llvm/MC/MCMachObjectWriter.h - Mach Object Writer --------*- C++ -*-===//
2 : //
3 : // The LLVM Compiler Infrastructure
4 : //
5 : // This file is distributed under the University of Illinois Open Source
6 : // License. See LICENSE.TXT for details.
7 : //
8 : //===----------------------------------------------------------------------===//
9 :
10 : #ifndef LLVM_MC_MCMACHOBJECTWRITER_H
11 : #define LLVM_MC_MCMACHOBJECTWRITER_H
12 :
13 : #include "llvm/ADT/DenseMap.h"
14 : #include "llvm/ADT/StringRef.h"
15 : #include "llvm/BinaryFormat/MachO.h"
16 : #include "llvm/MC/MCExpr.h"
17 : #include "llvm/MC/MCObjectWriter.h"
18 : #include "llvm/MC/MCSection.h"
19 : #include "llvm/MC/StringTableBuilder.h"
20 : #include <cstdint>
21 : #include <memory>
22 : #include <string>
23 : #include <vector>
24 :
25 : namespace llvm {
26 :
27 : class MachObjectWriter;
28 :
29 3036 : class MCMachObjectTargetWriter : public MCObjectTargetWriter {
30 : const unsigned Is64Bit : 1;
31 : const uint32_t CPUType;
32 : const uint32_t CPUSubtype;
33 : unsigned LocalDifference_RIT;
34 :
35 : protected:
36 : MCMachObjectTargetWriter(bool Is64Bit_, uint32_t CPUType_,
37 : uint32_t CPUSubtype_);
38 :
39 : void setLocalDifferenceRelocationType(unsigned Type) {
40 : LocalDifference_RIT = Type;
41 : }
42 :
43 : public:
44 : virtual ~MCMachObjectTargetWriter();
45 :
46 3050 : virtual Triple::ObjectFormatType getFormat() const { return Triple::MachO; }
47 : static bool classof(const MCObjectTargetWriter *W) {
48 : return W->getFormat() == Triple::MachO;
49 : }
50 :
51 : /// \name Lifetime Management
52 : /// @{
53 :
54 0 : virtual void reset() {}
55 :
56 : /// @}
57 :
58 : /// \name Accessors
59 : /// @{
60 :
61 16731 : bool is64Bit() const { return Is64Bit; }
62 0 : uint32_t getCPUType() const { return CPUType; }
63 0 : uint32_t getCPUSubtype() const { return CPUSubtype; }
64 : unsigned getLocalDifferenceRelocationType() const {
65 : return LocalDifference_RIT;
66 : }
67 :
68 : /// @}
69 :
70 : /// \name API
71 : /// @{
72 :
73 : virtual void recordRelocation(MachObjectWriter *Writer, MCAssembler &Asm,
74 : const MCAsmLayout &Layout,
75 : const MCFragment *Fragment,
76 : const MCFixup &Fixup, MCValue Target,
77 : uint64_t &FixedValue) = 0;
78 :
79 : /// @}
80 : };
81 :
82 : class MachObjectWriter : public MCObjectWriter {
83 : /// Helper struct for containing some precomputed information on symbols.
84 : struct MachSymbolData {
85 : const MCSymbol *Symbol;
86 : uint64_t StringIndex;
87 : uint8_t SectionIndex;
88 :
89 : // Support lexicographic sorting.
90 : bool operator<(const MachSymbolData &RHS) const;
91 : };
92 :
93 : /// The target specific Mach-O writer instance.
94 : std::unique_ptr<MCMachObjectTargetWriter> TargetObjectWriter;
95 :
96 : /// \name Relocation Data
97 : /// @{
98 :
99 : struct RelAndSymbol {
100 : const MCSymbol *Sym;
101 : MachO::any_relocation_info MRE;
102 : RelAndSymbol(const MCSymbol *Sym, const MachO::any_relocation_info &MRE)
103 0 : : Sym(Sym), MRE(MRE) {}
104 : };
105 :
106 : DenseMap<const MCSection *, std::vector<RelAndSymbol>> Relocations;
107 : DenseMap<const MCSection *, unsigned> IndirectSymBase;
108 :
109 : SectionAddrMap SectionAddress;
110 :
111 : /// @}
112 : /// \name Symbol Table Data
113 : /// @{
114 :
115 : StringTableBuilder StringTable{StringTableBuilder::MachO};
116 : std::vector<MachSymbolData> LocalSymbolData;
117 : std::vector<MachSymbolData> ExternalSymbolData;
118 : std::vector<MachSymbolData> UndefinedSymbolData;
119 :
120 : /// @}
121 :
122 : MachSymbolData *findSymbolData(const MCSymbol &Sym);
123 :
124 : void writeWithPadding(StringRef Str, uint64_t Size);
125 :
126 : public:
127 3050 : MachObjectWriter(std::unique_ptr<MCMachObjectTargetWriter> MOTW,
128 : raw_pwrite_stream &OS, bool IsLittleEndian)
129 3050 : : TargetObjectWriter(std::move(MOTW)),
130 6100 : W(OS, IsLittleEndian ? support::little : support::big) {}
131 :
132 : support::endian::Writer W;
133 :
134 : const MCSymbol &findAliasedSymbol(const MCSymbol &Sym) const;
135 :
136 : /// \name Lifetime management Methods
137 : /// @{
138 :
139 : void reset() override;
140 :
141 : /// @}
142 :
143 : /// \name Utility Methods
144 : /// @{
145 :
146 : bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind);
147 :
148 0 : SectionAddrMap &getSectionAddressMap() { return SectionAddress; }
149 :
150 : uint64_t getSectionAddress(const MCSection *Sec) const {
151 50054 : return SectionAddress.lookup(Sec);
152 : }
153 : uint64_t getSymbolAddress(const MCSymbol &S, const MCAsmLayout &Layout) const;
154 :
155 : uint64_t getFragmentAddress(const MCFragment *Fragment,
156 : const MCAsmLayout &Layout) const;
157 :
158 : uint64_t getPaddingSize(const MCSection *SD, const MCAsmLayout &Layout) const;
159 :
160 : bool doesSymbolRequireExternRelocation(const MCSymbol &S);
161 :
162 : /// @}
163 :
164 : /// \name Target Writer Proxy Accessors
165 : /// @{
166 :
167 : bool is64Bit() const { return TargetObjectWriter->is64Bit(); }
168 : bool isX86_64() const {
169 1162 : uint32_t CPUType = TargetObjectWriter->getCPUType();
170 : return CPUType == MachO::CPU_TYPE_X86_64;
171 : }
172 :
173 : /// @}
174 :
175 : void writeHeader(MachO::HeaderFileType Type, unsigned NumLoadCommands,
176 : unsigned LoadCommandsSize, bool SubsectionsViaSymbols);
177 :
178 : /// Write a segment load command.
179 : ///
180 : /// \param NumSections The number of sections in this segment.
181 : /// \param SectionDataSize The total size of the sections.
182 : void writeSegmentLoadCommand(StringRef Name, unsigned NumSections,
183 : uint64_t VMAddr, uint64_t VMSize,
184 : uint64_t SectionDataStartOffset,
185 : uint64_t SectionDataSize, uint32_t MaxProt,
186 : uint32_t InitProt);
187 :
188 : void writeSection(const MCAsmLayout &Layout, const MCSection &Sec,
189 : uint64_t VMAddr, uint64_t FileOffset, unsigned Flags,
190 : uint64_t RelocationsStart, unsigned NumRelocations);
191 :
192 : void writeSymtabLoadCommand(uint32_t SymbolOffset, uint32_t NumSymbols,
193 : uint32_t StringTableOffset,
194 : uint32_t StringTableSize);
195 :
196 : void writeDysymtabLoadCommand(
197 : uint32_t FirstLocalSymbol, uint32_t NumLocalSymbols,
198 : uint32_t FirstExternalSymbol, uint32_t NumExternalSymbols,
199 : uint32_t FirstUndefinedSymbol, uint32_t NumUndefinedSymbols,
200 : uint32_t IndirectSymbolOffset, uint32_t NumIndirectSymbols);
201 :
202 : void writeNlist(MachSymbolData &MSD, const MCAsmLayout &Layout);
203 :
204 : void writeLinkeditLoadCommand(uint32_t Type, uint32_t DataOffset,
205 : uint32_t DataSize);
206 :
207 : void writeLinkerOptionsLoadCommand(const std::vector<std::string> &Options);
208 :
209 : // FIXME: We really need to improve the relocation validation. Basically, we
210 : // want to implement a separate computation which evaluates the relocation
211 : // entry as the linker would, and verifies that the resultant fixup value is
212 : // exactly what the encoder wanted. This will catch several classes of
213 : // problems:
214 : //
215 : // - Relocation entry bugs, the two algorithms are unlikely to have the same
216 : // exact bug.
217 : //
218 : // - Relaxation issues, where we forget to relax something.
219 : //
220 : // - Input errors, where something cannot be correctly encoded. 'as' allows
221 : // these through in many cases.
222 :
223 : // Add a relocation to be output in the object file. At the time this is
224 : // called, the symbol indexes are not know, so if the relocation refers
225 : // to a symbol it should be passed as \p RelSymbol so that it can be updated
226 : // afterwards. If the relocation doesn't refer to a symbol, nullptr should be
227 : // used.
228 0 : void addRelocation(const MCSymbol *RelSymbol, const MCSection *Sec,
229 : MachO::any_relocation_info &MRE) {
230 : RelAndSymbol P(RelSymbol, MRE);
231 0 : Relocations[Sec].push_back(P);
232 0 : }
233 :
234 : void recordScatteredRelocation(const MCAssembler &Asm,
235 : const MCAsmLayout &Layout,
236 : const MCFragment *Fragment,
237 : const MCFixup &Fixup, MCValue Target,
238 : unsigned Log2Size, uint64_t &FixedValue);
239 :
240 : void recordTLVPRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
241 : const MCFragment *Fragment, const MCFixup &Fixup,
242 : MCValue Target, uint64_t &FixedValue);
243 :
244 : void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
245 : const MCFragment *Fragment, const MCFixup &Fixup,
246 : MCValue Target, uint64_t &FixedValue) override;
247 :
248 : void bindIndirectSymbols(MCAssembler &Asm);
249 :
250 : /// Compute the symbol table data.
251 : void computeSymbolTable(MCAssembler &Asm,
252 : std::vector<MachSymbolData> &LocalSymbolData,
253 : std::vector<MachSymbolData> &ExternalSymbolData,
254 : std::vector<MachSymbolData> &UndefinedSymbolData);
255 :
256 : void computeSectionAddresses(const MCAssembler &Asm,
257 : const MCAsmLayout &Layout);
258 :
259 : void executePostLayoutBinding(MCAssembler &Asm,
260 : const MCAsmLayout &Layout) override;
261 :
262 : bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
263 : const MCSymbol &A,
264 : const MCSymbol &B,
265 : bool InSet) const override;
266 :
267 : bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
268 : const MCSymbol &SymA,
269 : const MCFragment &FB, bool InSet,
270 : bool IsPCRel) const override;
271 :
272 : uint64_t writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
273 : };
274 :
275 : /// Construct a new Mach-O writer instance.
276 : ///
277 : /// This routine takes ownership of the target writer subclass.
278 : ///
279 : /// \param MOTW - The target specific Mach-O writer subclass.
280 : /// \param OS - The stream to write to.
281 : /// \returns The constructed object writer.
282 : std::unique_ptr<MCObjectWriter>
283 : createMachObjectWriter(std::unique_ptr<MCMachObjectTargetWriter> MOTW,
284 : raw_pwrite_stream &OS, bool IsLittleEndian);
285 :
286 : } // end namespace llvm
287 :
288 : #endif // LLVM_MC_MCMACHOBJECTWRITER_H
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