LLVM  8.0.0svn
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  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  virtual void reset() {}
55 
56  /// @}
57 
58  /// \name Accessors
59  /// @{
60 
61  bool is64Bit() const { return Is64Bit; }
62  uint32_t getCPUType() const { return CPUType; }
63  uint32_t getCPUSubtype() const { return CPUSubtype; }
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 
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;
102  RelAndSymbol(const MCSymbol *Sym, const MachO::any_relocation_info &MRE)
103  : Sym(Sym), MRE(MRE) {}
104  };
105 
108 
109  SectionAddrMap SectionAddress;
110 
111  /// @}
112  /// \name Symbol Table Data
113  /// @{
114 
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  MachObjectWriter(std::unique_ptr<MCMachObjectTargetWriter> MOTW,
128  raw_pwrite_stream &OS, bool IsLittleEndian)
129  : TargetObjectWriter(std::move(MOTW)),
130  W(OS, IsLittleEndian ? support::little : support::big) {}
131 
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  SectionAddrMap &getSectionAddressMap() { return SectionAddress; }
149 
150  uint64_t getSectionAddress(const MCSection *Sec) const {
151  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  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  void addRelocation(const MCSymbol *RelSymbol, const MCSection *Sec,
230  RelAndSymbol P(RelSymbol, MRE);
231  Relocations[Sec].push_back(P);
232  }
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
Instances of this class represent a uniqued identifier for a section in the current translation unit...
Definition: MCSection.h:39
This class represents lattice values for constants.
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:74
MachObjectWriter(std::unique_ptr< MCMachObjectTargetWriter > MOTW, raw_pwrite_stream &OS, bool IsLittleEndian)
support::endian::Writer W
amdgpu Simplify well known AMD library false Value Value const Twine & Name
Definition: BitVector.h:938
Encapsulates the layout of an assembly file at a particular point in time.
Definition: MCAsmLayout.h:29
HeaderFileType
Definition: MachO.h:37
virtual Triple::ObjectFormatType getFormat() const =0
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()
static bool classof(const MCObjectTargetWriter *W)
#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
virtual Triple::ObjectFormatType getFormat() const
unsigned getLocalDifferenceRelocationType() const
Target - Wrapper for Target specific information.
Adapter to write values to a stream in a particular byte order.
Definition: EndianStream.h:52
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.
uint32_t Size
Definition: Profile.cpp:47
Base class for classes that define behaviour that is specific to both the target and the object forma...
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:211
uint64_t getSectionAddress(const MCSection *Sec) const
An abstract base class for streams implementations that also support a pwrite operation.
Definition: raw_ostream.h:341
const unsigned Kind
ObjectFormatType
Definition: Triple.h:216
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_)