LLVM  6.0.0svn
MCMachObjectWriter.h
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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"
16 #include "llvm/MC/MCExpr.h"
17 #include "llvm/MC/MCObjectWriter.h"
18 #include "llvm/MC/MCSection.h"
20 #include <cstdint>
21 #include <memory>
22 #include <string>
23 #include <vector>
24 
25 namespace llvm {
26 
27 class MachObjectWriter;
28 
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 
40  LocalDifference_RIT = Type;
41  }
42 
43 public:
44  virtual ~MCMachObjectTargetWriter();
45 
46  /// \name Lifetime Management
47  /// @{
48 
49  virtual void reset() {}
50 
51  /// @}
52 
53  /// \name Accessors
54  /// @{
55 
56  bool is64Bit() const { return Is64Bit; }
57  uint32_t getCPUType() const { return CPUType; }
58  uint32_t getCPUSubtype() const { return CPUSubtype; }
60  return LocalDifference_RIT;
61  }
62 
63  /// @}
64 
65  /// \name API
66  /// @{
67 
68  virtual void recordRelocation(MachObjectWriter *Writer, MCAssembler &Asm,
69  const MCAsmLayout &Layout,
70  const MCFragment *Fragment,
71  const MCFixup &Fixup, MCValue Target,
72  uint64_t &FixedValue) = 0;
73 
74  /// @}
75 };
76 
78  /// Helper struct for containing some precomputed information on symbols.
79  struct MachSymbolData {
80  const MCSymbol *Symbol;
81  uint64_t StringIndex;
82  uint8_t SectionIndex;
83 
84  // Support lexicographic sorting.
85  bool operator<(const MachSymbolData &RHS) const;
86  };
87 
88  /// The target specific Mach-O writer instance.
89  std::unique_ptr<MCMachObjectTargetWriter> TargetObjectWriter;
90 
91  /// \name Relocation Data
92  /// @{
93 
94  struct RelAndSymbol {
95  const MCSymbol *Sym;
97  RelAndSymbol(const MCSymbol *Sym, const MachO::any_relocation_info &MRE)
98  : Sym(Sym), MRE(MRE) {}
99  };
100 
103 
104  SectionAddrMap SectionAddress;
105 
106  /// @}
107  /// \name Symbol Table Data
108  /// @{
109 
111  std::vector<MachSymbolData> LocalSymbolData;
112  std::vector<MachSymbolData> ExternalSymbolData;
113  std::vector<MachSymbolData> UndefinedSymbolData;
114 
115  /// @}
116 
117  MachSymbolData *findSymbolData(const MCSymbol &Sym);
118 
119 public:
120  MachObjectWriter(std::unique_ptr<MCMachObjectTargetWriter> MOTW,
121  raw_pwrite_stream &OS, bool IsLittleEndian)
122  : MCObjectWriter(OS, IsLittleEndian),
123  TargetObjectWriter(std::move(MOTW)) {}
124 
125  const MCSymbol &findAliasedSymbol(const MCSymbol &Sym) const;
126 
127  /// \name Lifetime management Methods
128  /// @{
129 
130  void reset() override;
131 
132  /// @}
133 
134  /// \name Utility Methods
135  /// @{
136 
137  bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind);
138 
139  SectionAddrMap &getSectionAddressMap() { return SectionAddress; }
140 
141  uint64_t getSectionAddress(const MCSection *Sec) const {
142  return SectionAddress.lookup(Sec);
143  }
144  uint64_t getSymbolAddress(const MCSymbol &S, const MCAsmLayout &Layout) const;
145 
146  uint64_t getFragmentAddress(const MCFragment *Fragment,
147  const MCAsmLayout &Layout) const;
148 
149  uint64_t getPaddingSize(const MCSection *SD, const MCAsmLayout &Layout) const;
150 
151  bool doesSymbolRequireExternRelocation(const MCSymbol &S);
152 
153  /// @}
154 
155  /// \name Target Writer Proxy Accessors
156  /// @{
157 
158  bool is64Bit() const { return TargetObjectWriter->is64Bit(); }
159  bool isX86_64() const {
160  uint32_t CPUType = TargetObjectWriter->getCPUType();
161  return CPUType == MachO::CPU_TYPE_X86_64;
162  }
163 
164  /// @}
165 
166  void writeHeader(MachO::HeaderFileType Type, unsigned NumLoadCommands,
167  unsigned LoadCommandsSize, bool SubsectionsViaSymbols);
168 
169  /// Write a segment load command.
170  ///
171  /// \param NumSections The number of sections in this segment.
172  /// \param SectionDataSize The total size of the sections.
173  void writeSegmentLoadCommand(StringRef Name, unsigned NumSections,
174  uint64_t VMAddr, uint64_t VMSize,
175  uint64_t SectionDataStartOffset,
176  uint64_t SectionDataSize, uint32_t MaxProt,
177  uint32_t InitProt);
178 
179  void writeSection(const MCAsmLayout &Layout, const MCSection &Sec,
180  uint64_t VMAddr, uint64_t FileOffset, unsigned Flags,
181  uint64_t RelocationsStart, unsigned NumRelocations);
182 
183  void writeSymtabLoadCommand(uint32_t SymbolOffset, uint32_t NumSymbols,
184  uint32_t StringTableOffset,
185  uint32_t StringTableSize);
186 
187  void writeDysymtabLoadCommand(
188  uint32_t FirstLocalSymbol, uint32_t NumLocalSymbols,
189  uint32_t FirstExternalSymbol, uint32_t NumExternalSymbols,
190  uint32_t FirstUndefinedSymbol, uint32_t NumUndefinedSymbols,
191  uint32_t IndirectSymbolOffset, uint32_t NumIndirectSymbols);
192 
193  void writeNlist(MachSymbolData &MSD, const MCAsmLayout &Layout);
194 
195  void writeLinkeditLoadCommand(uint32_t Type, uint32_t DataOffset,
196  uint32_t DataSize);
197 
198  void writeLinkerOptionsLoadCommand(const std::vector<std::string> &Options);
199 
200  // FIXME: We really need to improve the relocation validation. Basically, we
201  // want to implement a separate computation which evaluates the relocation
202  // entry as the linker would, and verifies that the resultant fixup value is
203  // exactly what the encoder wanted. This will catch several classes of
204  // problems:
205  //
206  // - Relocation entry bugs, the two algorithms are unlikely to have the same
207  // exact bug.
208  //
209  // - Relaxation issues, where we forget to relax something.
210  //
211  // - Input errors, where something cannot be correctly encoded. 'as' allows
212  // these through in many cases.
213 
214  // Add a relocation to be output in the object file. At the time this is
215  // called, the symbol indexes are not know, so if the relocation refers
216  // to a symbol it should be passed as \p RelSymbol so that it can be updated
217  // afterwards. If the relocation doesn't refer to a symbol, nullptr should be
218  // used.
219  void addRelocation(const MCSymbol *RelSymbol, const MCSection *Sec,
221  RelAndSymbol P(RelSymbol, MRE);
222  Relocations[Sec].push_back(P);
223  }
224 
225  void recordScatteredRelocation(const MCAssembler &Asm,
226  const MCAsmLayout &Layout,
227  const MCFragment *Fragment,
228  const MCFixup &Fixup, MCValue Target,
229  unsigned Log2Size, uint64_t &FixedValue);
230 
231  void recordTLVPRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
232  const MCFragment *Fragment, const MCFixup &Fixup,
233  MCValue Target, uint64_t &FixedValue);
234 
235  void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
236  const MCFragment *Fragment, const MCFixup &Fixup,
237  MCValue Target, uint64_t &FixedValue) override;
238 
239  void bindIndirectSymbols(MCAssembler &Asm);
240 
241  /// Compute the symbol table data.
242  void computeSymbolTable(MCAssembler &Asm,
243  std::vector<MachSymbolData> &LocalSymbolData,
244  std::vector<MachSymbolData> &ExternalSymbolData,
245  std::vector<MachSymbolData> &UndefinedSymbolData);
246 
247  void computeSectionAddresses(const MCAssembler &Asm,
248  const MCAsmLayout &Layout);
249 
250  void executePostLayoutBinding(MCAssembler &Asm,
251  const MCAsmLayout &Layout) override;
252 
253  bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
254  const MCSymbol &A,
255  const MCSymbol &B,
256  bool InSet) const override;
257 
258  bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
259  const MCSymbol &SymA,
260  const MCFragment &FB, bool InSet,
261  bool IsPCRel) const override;
262 
263  void writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
264 };
265 
266 /// Construct a new Mach-O writer instance.
267 ///
268 /// This routine takes ownership of the target writer subclass.
269 ///
270 /// \param MOTW - The target specific Mach-O writer subclass.
271 /// \param OS - The stream to write to.
272 /// \returns The constructed object writer.
273 std::unique_ptr<MCObjectWriter>
274 createMachObjectWriter(std::unique_ptr<MCMachObjectTargetWriter> MOTW,
275  raw_pwrite_stream &OS, bool IsLittleEndian);
276 
277 } // end namespace llvm
278 
279 #endif // LLVM_MC_MCMACHOBJECTWRITER_H
Instances of this class represent a uniqued identifier for a section in the current translation unit...
Definition: MCSection.h:39
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
This represents an "assembler immediate".
Definition: MCValue.h:40
MCSymbol - Instances of this class represent a symbol name in the MC file, and MCSymbols are created ...
Definition: MCSymbol.h:42
Defines the object file and target independent interfaces used by the assembler backend to write nati...
Encode information on a single operation to perform on a byte sequence (e.g., an encoded instruction)...
Definition: MCFixup.h:66
MachObjectWriter(std::unique_ptr< MCMachObjectTargetWriter > MOTW, raw_pwrite_stream &OS, bool IsLittleEndian)
Definition: BitVector.h:920
Encapsulates the layout of an assembly file at a particular point in time.
Definition: MCAsmLayout.h:29
HeaderFileType
Definition: MachO.h:37
void setLocalDifferenceRelocationType(unsigned Type)
Utility for building string tables with deduplicated suffixes.
void addRelocation(const MCSymbol *RelSymbol, const MCSection *Sec, MachO::any_relocation_info &MRE)
SectionAddrMap & getSectionAddressMap()
#define P(N)
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:46
PowerPC TLS Dynamic Call Fixup
unsigned getLocalDifferenceRelocationType() const
Target - Wrapper for Target specific information.
virtual void recordRelocation(MachObjectWriter *Writer, MCAssembler &Asm, const MCAsmLayout &Layout, const MCFragment *Fragment, const MCFixup &Fixup, MCValue Target, uint64_t &FixedValue)=0
std::unique_ptr< MCObjectWriter > createMachObjectWriter(std::unique_ptr< MCMachObjectTargetWriter > MOTW, raw_pwrite_stream &OS, bool IsLittleEndian)
Construct a new Mach-O writer instance.
ValueT lookup(const_arg_type_t< KeyT > Val) const
lookup - Return the entry for the specified key, or a default constructed value if no such entry exis...
Definition: DenseMap.h:181
uint64_t getSectionAddress(const MCSection *Sec) const
An abstract base class for streams implementations that also support a pwrite operation.
Definition: raw_ostream.h:337
const unsigned Kind
bool operator<(int64_t V1, const APSInt &V2)
Definition: APSInt.h:326
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:49
MCMachObjectTargetWriter(bool Is64Bit_, uint32_t CPUType_, uint32_t CPUSubtype_)