• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1 //===- ELF.h - ELF object file implementation -------------------*- 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 // This file declares the ELFFile template class.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_OBJECT_ELF_H
15 #define LLVM_OBJECT_ELF_H
16 
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/Object/ELFTypes.h"
19 #include "llvm/Support/MemoryBuffer.h"
20 
21 namespace llvm {
22 namespace object {
23 
24 StringRef getELFRelocationTypeName(uint32_t Machine, uint32_t Type);
25 
26 // Subclasses of ELFFile may need this for template instantiation
27 inline std::pair<unsigned char, unsigned char>
getElfArchType(StringRef Object)28 getElfArchType(StringRef Object) {
29   if (Object.size() < ELF::EI_NIDENT)
30     return std::make_pair((uint8_t)ELF::ELFCLASSNONE,
31                           (uint8_t)ELF::ELFDATANONE);
32   return std::make_pair((uint8_t)Object[ELF::EI_CLASS],
33                         (uint8_t)Object[ELF::EI_DATA]);
34 }
35 
36 template <class ELFT>
37 class ELFFile {
38 public:
39   LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
40   typedef typename std::conditional<ELFT::Is64Bits,
41                                     uint64_t, uint32_t>::type uintX_t;
42 
43   typedef Elf_Ehdr_Impl<ELFT> Elf_Ehdr;
44   typedef Elf_Shdr_Impl<ELFT> Elf_Shdr;
45   typedef Elf_Sym_Impl<ELFT> Elf_Sym;
46   typedef Elf_Dyn_Impl<ELFT> Elf_Dyn;
47   typedef Elf_Phdr_Impl<ELFT> Elf_Phdr;
48   typedef Elf_Rel_Impl<ELFT, false> Elf_Rel;
49   typedef Elf_Rel_Impl<ELFT, true> Elf_Rela;
50   typedef Elf_Verdef_Impl<ELFT> Elf_Verdef;
51   typedef Elf_Verdaux_Impl<ELFT> Elf_Verdaux;
52   typedef Elf_Verneed_Impl<ELFT> Elf_Verneed;
53   typedef Elf_Vernaux_Impl<ELFT> Elf_Vernaux;
54   typedef Elf_Versym_Impl<ELFT> Elf_Versym;
55   typedef Elf_Hash_Impl<ELFT> Elf_Hash;
56   typedef Elf_GnuHash_Impl<ELFT> Elf_GnuHash;
57   typedef typename ELFT::DynRange Elf_Dyn_Range;
58   typedef typename ELFT::ShdrRange Elf_Shdr_Range;
59   typedef typename ELFT::SymRange Elf_Sym_Range;
60   typedef typename ELFT::RelRange Elf_Rel_Range;
61   typedef typename ELFT::RelaRange Elf_Rela_Range;
62   typedef typename ELFT::PhdrRange Elf_Phdr_Range;
63 
base()64   const uint8_t *base() const {
65     return reinterpret_cast<const uint8_t *>(Buf.data());
66   }
67 
getBufSize()68   size_t getBufSize() const { return Buf.size(); }
69 
70 private:
71 
72   StringRef Buf;
73 
74   const Elf_Ehdr *Header;
75   const Elf_Shdr *SectionHeaderTable = nullptr;
76   StringRef DotShstrtab;                    // Section header string table.
77 
78 public:
79   template<typename T>
80   const T        *getEntry(uint32_t Section, uint32_t Entry) const;
81   template <typename T>
82   const T *getEntry(const Elf_Shdr *Section, uint32_t Entry) const;
83 
84   ErrorOr<StringRef> getStringTable(const Elf_Shdr *Section) const;
85   ErrorOr<StringRef> getStringTableForSymtab(const Elf_Shdr &Section) const;
86 
87   ErrorOr<ArrayRef<Elf_Word>> getSHNDXTable(const Elf_Shdr &Section) const;
88 
89   void VerifyStrTab(const Elf_Shdr *sh) const;
90 
91   StringRef getRelocationTypeName(uint32_t Type) const;
92   void getRelocationTypeName(uint32_t Type,
93                              SmallVectorImpl<char> &Result) const;
94 
95   /// \brief Get the symbol for a given relocation.
96   const Elf_Sym *getRelocationSymbol(const Elf_Rel *Rel,
97                                      const Elf_Shdr *SymTab) const;
98 
99   ELFFile(StringRef Object, std::error_code &EC);
100 
isMipsELF64()101   bool isMipsELF64() const {
102     return Header->e_machine == ELF::EM_MIPS &&
103       Header->getFileClass() == ELF::ELFCLASS64;
104   }
105 
isMips64EL()106   bool isMips64EL() const {
107     return Header->e_machine == ELF::EM_MIPS &&
108       Header->getFileClass() == ELF::ELFCLASS64 &&
109       Header->getDataEncoding() == ELF::ELFDATA2LSB;
110   }
111 
112   const Elf_Shdr *section_begin() const;
113   const Elf_Shdr *section_end() const;
sections()114   Elf_Shdr_Range sections() const {
115     return makeArrayRef(section_begin(), section_end());
116   }
117 
symbol_begin(const Elf_Shdr * Sec)118   const Elf_Sym *symbol_begin(const Elf_Shdr *Sec) const {
119     if (!Sec)
120       return nullptr;
121     if (Sec->sh_entsize != sizeof(Elf_Sym))
122       report_fatal_error("Invalid symbol size");
123     return reinterpret_cast<const Elf_Sym *>(base() + Sec->sh_offset);
124   }
symbol_end(const Elf_Shdr * Sec)125   const Elf_Sym *symbol_end(const Elf_Shdr *Sec) const {
126     if (!Sec)
127       return nullptr;
128     uint64_t Size = Sec->sh_size;
129     if (Size % sizeof(Elf_Sym))
130       report_fatal_error("Invalid symbol table size");
131     return symbol_begin(Sec) + Size / sizeof(Elf_Sym);
132   }
symbols(const Elf_Shdr * Sec)133   Elf_Sym_Range symbols(const Elf_Shdr *Sec) const {
134     return makeArrayRef(symbol_begin(Sec), symbol_end(Sec));
135   }
136 
rela_begin(const Elf_Shdr * sec)137   const Elf_Rela *rela_begin(const Elf_Shdr *sec) const {
138     if (sec->sh_entsize != sizeof(Elf_Rela))
139       report_fatal_error("Invalid relocation entry size");
140     return reinterpret_cast<const Elf_Rela *>(base() + sec->sh_offset);
141   }
142 
rela_end(const Elf_Shdr * sec)143   const Elf_Rela *rela_end(const Elf_Shdr *sec) const {
144     uint64_t Size = sec->sh_size;
145     if (Size % sizeof(Elf_Rela))
146       report_fatal_error("Invalid relocation table size");
147     return rela_begin(sec) + Size / sizeof(Elf_Rela);
148   }
149 
relas(const Elf_Shdr * Sec)150   Elf_Rela_Range relas(const Elf_Shdr *Sec) const {
151     return makeArrayRef(rela_begin(Sec), rela_end(Sec));
152   }
153 
rel_begin(const Elf_Shdr * sec)154   const Elf_Rel *rel_begin(const Elf_Shdr *sec) const {
155     if (sec->sh_entsize != sizeof(Elf_Rel))
156       report_fatal_error("Invalid relocation entry size");
157     return reinterpret_cast<const Elf_Rel *>(base() + sec->sh_offset);
158   }
159 
rel_end(const Elf_Shdr * sec)160   const Elf_Rel *rel_end(const Elf_Shdr *sec) const {
161     uint64_t Size = sec->sh_size;
162     if (Size % sizeof(Elf_Rel))
163       report_fatal_error("Invalid relocation table size");
164     return rel_begin(sec) + Size / sizeof(Elf_Rel);
165   }
166 
rels(const Elf_Shdr * Sec)167   Elf_Rel_Range rels(const Elf_Shdr *Sec) const {
168     return makeArrayRef(rel_begin(Sec), rel_end(Sec));
169   }
170 
171   /// \brief Iterate over program header table.
program_header_begin()172   const Elf_Phdr *program_header_begin() const {
173     if (Header->e_phnum && Header->e_phentsize != sizeof(Elf_Phdr))
174       report_fatal_error("Invalid program header size");
175     return reinterpret_cast<const Elf_Phdr *>(base() + Header->e_phoff);
176   }
177 
program_header_end()178   const Elf_Phdr *program_header_end() const {
179     return program_header_begin() + Header->e_phnum;
180   }
181 
program_headers()182   const Elf_Phdr_Range program_headers() const {
183     return makeArrayRef(program_header_begin(), program_header_end());
184   }
185 
186   uint64_t getNumSections() const;
187   uintX_t getStringTableIndex() const;
188   uint32_t getExtendedSymbolTableIndex(const Elf_Sym *Sym,
189                                        const Elf_Shdr *SymTab,
190                                        ArrayRef<Elf_Word> ShndxTable) const;
191   uint32_t getExtendedSymbolTableIndex(const Elf_Sym *Sym,
192                                        const Elf_Sym *FirstSym,
193                                        ArrayRef<Elf_Word> ShndxTable) const;
getHeader()194   const Elf_Ehdr *getHeader() const { return Header; }
195   ErrorOr<const Elf_Shdr *> getSection(const Elf_Sym *Sym,
196                                        const Elf_Shdr *SymTab,
197                                        ArrayRef<Elf_Word> ShndxTable) const;
198   ErrorOr<const Elf_Shdr *> getSection(uint32_t Index) const;
199 
getSymbol(const Elf_Shdr * Sec,uint32_t Index)200   const Elf_Sym *getSymbol(const Elf_Shdr *Sec, uint32_t Index) const {
201     return &*(symbol_begin(Sec) + Index);
202   }
203 
204   ErrorOr<StringRef> getSectionName(const Elf_Shdr *Section) const;
205   template <typename T>
206   ErrorOr<ArrayRef<T>> getSectionContentsAsArray(const Elf_Shdr *Sec) const;
207   ErrorOr<ArrayRef<uint8_t> > getSectionContents(const Elf_Shdr *Sec) const;
208 };
209 
210 typedef ELFFile<ELFType<support::little, false>> ELF32LEFile;
211 typedef ELFFile<ELFType<support::little, true>> ELF64LEFile;
212 typedef ELFFile<ELFType<support::big, false>> ELF32BEFile;
213 typedef ELFFile<ELFType<support::big, true>> ELF64BEFile;
214 
215 template <class ELFT>
getExtendedSymbolTableIndex(const Elf_Sym * Sym,const Elf_Shdr * SymTab,ArrayRef<Elf_Word> ShndxTable)216 uint32_t ELFFile<ELFT>::getExtendedSymbolTableIndex(
217     const Elf_Sym *Sym, const Elf_Shdr *SymTab,
218     ArrayRef<Elf_Word> ShndxTable) const {
219   return getExtendedSymbolTableIndex(Sym, symbol_begin(SymTab), ShndxTable);
220 }
221 
222 template <class ELFT>
getExtendedSymbolTableIndex(const Elf_Sym * Sym,const Elf_Sym * FirstSym,ArrayRef<Elf_Word> ShndxTable)223 uint32_t ELFFile<ELFT>::getExtendedSymbolTableIndex(
224     const Elf_Sym *Sym, const Elf_Sym *FirstSym,
225     ArrayRef<Elf_Word> ShndxTable) const {
226   assert(Sym->st_shndx == ELF::SHN_XINDEX);
227   unsigned Index = Sym - FirstSym;
228 
229   // The size of the table was checked in getSHNDXTable.
230   return ShndxTable[Index];
231 }
232 
233 template <class ELFT>
234 ErrorOr<const typename ELFFile<ELFT>::Elf_Shdr *>
getSection(const Elf_Sym * Sym,const Elf_Shdr * SymTab,ArrayRef<Elf_Word> ShndxTable)235 ELFFile<ELFT>::getSection(const Elf_Sym *Sym, const Elf_Shdr *SymTab,
236                           ArrayRef<Elf_Word> ShndxTable) const {
237   uint32_t Index = Sym->st_shndx;
238   if (Index == ELF::SHN_XINDEX)
239     return getSection(getExtendedSymbolTableIndex(Sym, SymTab, ShndxTable));
240 
241   if (Index == ELF::SHN_UNDEF || Index >= ELF::SHN_LORESERVE)
242     return nullptr;
243   return getSection(Sym->st_shndx);
244 }
245 
246 template <class ELFT>
247 template <typename T>
248 ErrorOr<ArrayRef<T>>
getSectionContentsAsArray(const Elf_Shdr * Sec)249 ELFFile<ELFT>::getSectionContentsAsArray(const Elf_Shdr *Sec) const {
250   uintX_t Offset = Sec->sh_offset;
251   uintX_t Size = Sec->sh_size;
252 
253   if (Size % sizeof(T))
254     return object_error::parse_failed;
255   if (Offset + Size > Buf.size())
256     return object_error::parse_failed;
257 
258   const T *Start = reinterpret_cast<const T *>(base() + Offset);
259   return makeArrayRef(Start, Size / sizeof(T));
260 }
261 
262 template <class ELFT>
263 ErrorOr<ArrayRef<uint8_t>>
getSectionContents(const Elf_Shdr * Sec)264 ELFFile<ELFT>::getSectionContents(const Elf_Shdr *Sec) const {
265   return getSectionContentsAsArray<uint8_t>(Sec);
266 }
267 
268 template <class ELFT>
getRelocationTypeName(uint32_t Type)269 StringRef ELFFile<ELFT>::getRelocationTypeName(uint32_t Type) const {
270   return getELFRelocationTypeName(Header->e_machine, Type);
271 }
272 
273 template <class ELFT>
getRelocationTypeName(uint32_t Type,SmallVectorImpl<char> & Result)274 void ELFFile<ELFT>::getRelocationTypeName(uint32_t Type,
275                                           SmallVectorImpl<char> &Result) const {
276   if (!isMipsELF64()) {
277     StringRef Name = getRelocationTypeName(Type);
278     Result.append(Name.begin(), Name.end());
279   } else {
280     // The Mips N64 ABI allows up to three operations to be specified per
281     // relocation record. Unfortunately there's no easy way to test for the
282     // presence of N64 ELFs as they have no special flag that identifies them
283     // as being N64. We can safely assume at the moment that all Mips
284     // ELFCLASS64 ELFs are N64. New Mips64 ABIs should provide enough
285     // information to disambiguate between old vs new ABIs.
286     uint8_t Type1 = (Type >> 0) & 0xFF;
287     uint8_t Type2 = (Type >> 8) & 0xFF;
288     uint8_t Type3 = (Type >> 16) & 0xFF;
289 
290     // Concat all three relocation type names.
291     StringRef Name = getRelocationTypeName(Type1);
292     Result.append(Name.begin(), Name.end());
293 
294     Name = getRelocationTypeName(Type2);
295     Result.append(1, '/');
296     Result.append(Name.begin(), Name.end());
297 
298     Name = getRelocationTypeName(Type3);
299     Result.append(1, '/');
300     Result.append(Name.begin(), Name.end());
301   }
302 }
303 
304 template <class ELFT>
305 const typename ELFFile<ELFT>::Elf_Sym *
getRelocationSymbol(const Elf_Rel * Rel,const Elf_Shdr * SymTab)306 ELFFile<ELFT>::getRelocationSymbol(const Elf_Rel *Rel,
307                                    const Elf_Shdr *SymTab) const {
308   uint32_t Index = Rel->getSymbol(isMips64EL());
309   if (Index == 0)
310     return nullptr;
311   return getEntry<Elf_Sym>(SymTab, Index);
312 }
313 
314 template <class ELFT>
getNumSections()315 uint64_t ELFFile<ELFT>::getNumSections() const {
316   assert(Header && "Header not initialized!");
317   if (Header->e_shnum == ELF::SHN_UNDEF && Header->e_shoff > 0) {
318     assert(SectionHeaderTable && "SectionHeaderTable not initialized!");
319     return SectionHeaderTable->sh_size;
320   }
321   return Header->e_shnum;
322 }
323 
324 template <class ELFT>
getStringTableIndex()325 typename ELFFile<ELFT>::uintX_t ELFFile<ELFT>::getStringTableIndex() const {
326   if (Header->e_shnum == ELF::SHN_UNDEF) {
327     if (Header->e_shstrndx == ELF::SHN_HIRESERVE)
328       return SectionHeaderTable->sh_link;
329     if (Header->e_shstrndx >= getNumSections())
330       return 0;
331   }
332   return Header->e_shstrndx;
333 }
334 
335 template <class ELFT>
ELFFile(StringRef Object,std::error_code & EC)336 ELFFile<ELFT>::ELFFile(StringRef Object, std::error_code &EC)
337     : Buf(Object) {
338   const uint64_t FileSize = Buf.size();
339 
340   if (sizeof(Elf_Ehdr) > FileSize) {
341     // File too short!
342     EC = object_error::parse_failed;
343     return;
344   }
345 
346   Header = reinterpret_cast<const Elf_Ehdr *>(base());
347 
348   if (Header->e_shoff == 0)
349     return;
350 
351   const uint64_t SectionTableOffset = Header->e_shoff;
352 
353   if (SectionTableOffset + sizeof(Elf_Shdr) > FileSize) {
354     // Section header table goes past end of file!
355     EC = object_error::parse_failed;
356     return;
357   }
358 
359   // The getNumSections() call below depends on SectionHeaderTable being set.
360   SectionHeaderTable =
361     reinterpret_cast<const Elf_Shdr *>(base() + SectionTableOffset);
362   const uint64_t SectionTableSize = getNumSections() * Header->e_shentsize;
363 
364   if (SectionTableOffset + SectionTableSize > FileSize) {
365     // Section table goes past end of file!
366     EC = object_error::parse_failed;
367     return;
368   }
369 
370   // Get string table sections.
371   uintX_t StringTableIndex = getStringTableIndex();
372   if (StringTableIndex) {
373     ErrorOr<const Elf_Shdr *> StrTabSecOrErr = getSection(StringTableIndex);
374     if ((EC = StrTabSecOrErr.getError()))
375       return;
376 
377     ErrorOr<StringRef> StringTableOrErr = getStringTable(*StrTabSecOrErr);
378     if ((EC = StringTableOrErr.getError()))
379       return;
380     DotShstrtab = *StringTableOrErr;
381   }
382 
383   EC = std::error_code();
384 }
385 
386 template <class ELFT>
compareAddr(uint64_t VAddr,const Elf_Phdr_Impl<ELFT> * Phdr)387 static bool compareAddr(uint64_t VAddr, const Elf_Phdr_Impl<ELFT> *Phdr) {
388   return VAddr < Phdr->p_vaddr;
389 }
390 
391 template <class ELFT>
section_begin()392 const typename ELFFile<ELFT>::Elf_Shdr *ELFFile<ELFT>::section_begin() const {
393   if (Header->e_shentsize != sizeof(Elf_Shdr))
394     report_fatal_error(
395         "Invalid section header entry size (e_shentsize) in ELF header");
396   return reinterpret_cast<const Elf_Shdr *>(base() + Header->e_shoff);
397 }
398 
399 template <class ELFT>
section_end()400 const typename ELFFile<ELFT>::Elf_Shdr *ELFFile<ELFT>::section_end() const {
401   return section_begin() + getNumSections();
402 }
403 
404 template <class ELFT>
405 template <typename T>
getEntry(uint32_t Section,uint32_t Entry)406 const T *ELFFile<ELFT>::getEntry(uint32_t Section, uint32_t Entry) const {
407   ErrorOr<const Elf_Shdr *> Sec = getSection(Section);
408   if (std::error_code EC = Sec.getError())
409     report_fatal_error(EC.message());
410   return getEntry<T>(*Sec, Entry);
411 }
412 
413 template <class ELFT>
414 template <typename T>
getEntry(const Elf_Shdr * Section,uint32_t Entry)415 const T *ELFFile<ELFT>::getEntry(const Elf_Shdr *Section,
416                                  uint32_t Entry) const {
417   return reinterpret_cast<const T *>(base() + Section->sh_offset +
418                                      (Entry * Section->sh_entsize));
419 }
420 
421 template <class ELFT>
422 ErrorOr<const typename ELFFile<ELFT>::Elf_Shdr *>
getSection(uint32_t Index)423 ELFFile<ELFT>::getSection(uint32_t Index) const {
424   assert(SectionHeaderTable && "SectionHeaderTable not initialized!");
425   if (Index >= getNumSections())
426     return object_error::invalid_section_index;
427 
428   return reinterpret_cast<const Elf_Shdr *>(
429       reinterpret_cast<const char *>(SectionHeaderTable) +
430       (Index * Header->e_shentsize));
431 }
432 
433 template <class ELFT>
434 ErrorOr<StringRef>
getStringTable(const Elf_Shdr * Section)435 ELFFile<ELFT>::getStringTable(const Elf_Shdr *Section) const {
436   if (Section->sh_type != ELF::SHT_STRTAB)
437     return object_error::parse_failed;
438   uint64_t Offset = Section->sh_offset;
439   uint64_t Size = Section->sh_size;
440   if (Offset + Size > Buf.size())
441     return object_error::parse_failed;
442   StringRef Data((const char *)base() + Section->sh_offset, Size);
443   if (Data[Size - 1] != '\0')
444     return object_error::string_table_non_null_end;
445   return Data;
446 }
447 
448 template <class ELFT>
449 ErrorOr<ArrayRef<typename ELFFile<ELFT>::Elf_Word>>
getSHNDXTable(const Elf_Shdr & Section)450 ELFFile<ELFT>::getSHNDXTable(const Elf_Shdr &Section) const {
451   assert(Section.sh_type == ELF::SHT_SYMTAB_SHNDX);
452   const Elf_Word *ShndxTableBegin =
453       reinterpret_cast<const Elf_Word *>(base() + Section.sh_offset);
454   uintX_t Size = Section.sh_size;
455   if (Size % sizeof(uint32_t))
456     return object_error::parse_failed;
457   uintX_t NumSymbols = Size / sizeof(uint32_t);
458   const Elf_Word *ShndxTableEnd = ShndxTableBegin + NumSymbols;
459   if (reinterpret_cast<const char *>(ShndxTableEnd) > Buf.end())
460     return object_error::parse_failed;
461   ErrorOr<const Elf_Shdr *> SymTableOrErr = getSection(Section.sh_link);
462   if (std::error_code EC = SymTableOrErr.getError())
463     return EC;
464   const Elf_Shdr &SymTable = **SymTableOrErr;
465   if (SymTable.sh_type != ELF::SHT_SYMTAB &&
466       SymTable.sh_type != ELF::SHT_DYNSYM)
467     return object_error::parse_failed;
468   if (NumSymbols != (SymTable.sh_size / sizeof(Elf_Sym)))
469     return object_error::parse_failed;
470   return makeArrayRef(ShndxTableBegin, ShndxTableEnd);
471 }
472 
473 template <class ELFT>
474 ErrorOr<StringRef>
getStringTableForSymtab(const Elf_Shdr & Sec)475 ELFFile<ELFT>::getStringTableForSymtab(const Elf_Shdr &Sec) const {
476   if (Sec.sh_type != ELF::SHT_SYMTAB && Sec.sh_type != ELF::SHT_DYNSYM)
477     return object_error::parse_failed;
478   ErrorOr<const Elf_Shdr *> SectionOrErr = getSection(Sec.sh_link);
479   if (std::error_code EC = SectionOrErr.getError())
480     return EC;
481   return getStringTable(*SectionOrErr);
482 }
483 
484 template <class ELFT>
485 ErrorOr<StringRef>
getSectionName(const Elf_Shdr * Section)486 ELFFile<ELFT>::getSectionName(const Elf_Shdr *Section) const {
487   uint32_t Offset = Section->sh_name;
488   if (Offset == 0)
489     return StringRef();
490   if (Offset >= DotShstrtab.size())
491     return object_error::parse_failed;
492   return StringRef(DotShstrtab.data() + Offset);
493 }
494 
495 /// This function returns the hash value for a symbol in the .dynsym section
496 /// Name of the API remains consistent as specified in the libelf
497 /// REF : http://www.sco.com/developers/gabi/latest/ch5.dynamic.html#hash
elf_hash(StringRef & symbolName)498 static inline unsigned elf_hash(StringRef &symbolName) {
499   unsigned h = 0, g;
500   for (unsigned i = 0, j = symbolName.size(); i < j; i++) {
501     h = (h << 4) + symbolName[i];
502     g = h & 0xf0000000L;
503     if (g != 0)
504       h ^= g >> 24;
505     h &= ~g;
506   }
507   return h;
508 }
509 } // end namespace object
510 } // end namespace llvm
511 
512 #endif
513