text: //===- ELF.h - ELF object file implementation -------------------*- C++ -*-===//
  //
  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  // See https://llvm.org/LICENSE.txt for license information.
  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  //
  //===----------------------------------------------------------------------===//
  //
  // This file declares the ELFFile template class.
  //
  //===----------------------------------------------------------------------===//
  
  #ifndef LLVM_OBJECT_ELF_H
  #define LLVM_OBJECT_ELF_H
  
  #include "llvm/ADT/ArrayRef.h"
  #include "llvm/ADT/SmallVector.h"
  #include "llvm/ADT/StringRef.h"
  #include "llvm/BinaryFormat/ELF.h"
  #include "llvm/Object/ELFTypes.h"
  #include "llvm/Object/Error.h"
  #include "llvm/Support/Endian.h"
  #include "llvm/Support/Error.h"
  #include <cassert>
  #include <cstddef>
  #include <cstdint>
  #include <limits>
  #include <utility>
  
  namespace llvm {
  namespace object {
  
  struct VerdAux {
    unsigned Offset;
    std::string Name;
  };
  
  struct VerDef {
    unsigned Offset;
    unsigned Version;
    unsigned Flags;
    unsigned Ndx;
    unsigned Cnt;
    unsigned Hash;
    std::string Name;
    std::vector<VerdAux> AuxV;
  };
  
  struct VernAux {
    unsigned Hash;
    unsigned Flags;
    unsigned Other;
    unsigned Offset;
    std::string Name;
  };
  
  struct VerNeed {
    unsigned Version;
    unsigned Cnt;
    unsigned Offset;
    std::string File;
    std::vector<VernAux> AuxV;
  };
  
  struct VersionEntry {
    std::string Name;
    bool IsVerDef;
  };
  
  StringRef getELFRelocationTypeName(uint32_t Machine, uint32_t Type);
  uint32_t getELFRelativeRelocationType(uint32_t Machine);
  StringRef getELFSectionTypeName(uint32_t Machine, uint32_t Type);
  
  // Subclasses of ELFFile may need this for template instantiation
  inline std::pair<unsigned char, unsigned char>
  getElfArchType(StringRef Object) {
    if (Object.size() < ELF::EI_NIDENT)
      return std::make_pair((uint8_t)ELF::ELFCLASSNONE,
                            (uint8_t)ELF::ELFDATANONE);
    return std::make_pair((uint8_t)Object[ELF::EI_CLASS],
                          (uint8_t)Object[ELF::EI_DATA]);
  }
  
  static inline Error createError(const Twine &Err) {
    return make_error<StringError>(Err, object_error::parse_failed);
  }
  
  enum PPCInstrMasks : uint64_t {
    PADDI_R12_NO_DISP = 0x0610000039800000,
    PLD_R12_NO_DISP = 0x04100000E5800000,
    MTCTR_R12 = 0x7D8903A6,
    BCTR = 0x4E800420,
  };
  
  template <class ELFT> class ELFFile;
  
  template <class T> struct DataRegion {
    // This constructor is used when we know the start and the size of a data
    // region. We assume that Arr does not go past the end of the file.
    DataRegion(ArrayRef<T> Arr) : First(Arr.data()), Size(Arr.size()) {}
  
    // Sometimes we only know the start of a data region. We still don't want to
    // read past the end of the file, so we provide the end of a buffer.
    DataRegion(const T *Data, const uint8_t *BufferEnd)
        : First(Data), BufEnd(BufferEnd) {}
  
    Expected<T> operator[](uint64_t N) {
      assert(Size || BufEnd);
      if (Size) {
        if (N >= *Size)
          return createError(
              "the index is greater than or equal to the number of entries (" +
              Twine(*Size) + ")");
      } else {
        const uint8_t *EntryStart = (const uint8_t *)First + N * sizeof(T);
        if (EntryStart + sizeof(T) > BufEnd)
          return createError("can't read past the end of the file");
      }
      return *(First + N);
    }
  
    const T *First;
    Optional<uint64_t> Size = None;
    const uint8_t *BufEnd = nullptr;
  };
  
  template <class ELFT>
  std::string getSecIndexForError(const ELFFile<ELFT> &Obj,
                                  const typename ELFT::Shdr &Sec) {
    auto TableOrErr = Obj.sections();
    if (TableOrErr)
      return "[index " + std::to_string(&Sec - &TableOrErr->front()) + "]";
    // To make this helper be more convenient for error reporting purposes we
    // drop the error. But really it should never be triggered. Before this point,
    // our code should have called 'sections()' and reported a proper error on
    // failure.
    llvm::consumeError(TableOrErr.takeError());
    return "[unknown index]";
  }
  
  template <class ELFT>
  static std::string describe(const ELFFile<ELFT> &Obj,
                              const typename ELFT::Shdr &Sec) {
    unsigned SecNdx = &Sec - &cantFail(Obj.sections()).front();
    return (object::getELFSectionTypeName(Obj.getHeader().e_machine,
                                          Sec.sh_type) +
            " section with index " + Twine(SecNdx))
        .str();
  }
  
  template <class ELFT>
  std::string getPhdrIndexForError(const ELFFile<ELFT> &Obj,
                                   const typename ELFT::Phdr &Phdr) {
    auto Headers = Obj.program_headers();
    if (Headers)
      return ("[index " + Twine(&Phdr - &Headers->front()) + "]").str();
    // See comment in the getSecIndexForError() above.
    llvm::consumeError(Headers.takeError());
    return "[unknown index]";
  }
  
  static inline Error defaultWarningHandler(const Twine &Msg) {
    return createError(Msg);
  }
  
  template <class ELFT>
  class ELFFile {
  public:
    LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
  
    // This is a callback that can be passed to a number of functions.
    // It can be used to ignore non-critical errors (warnings), which is
    // useful for dumpers, like llvm-readobj.
    // It accepts a warning message string and returns a success
    // when the warning should be ignored or an error otherwise.
    using WarningHandler = llvm::function_ref<Error(const Twine &Msg)>;
  
    const uint8_t *base() const { return Buf.bytes_begin(); }
    const uint8_t *end() const { return base() + getBufSize(); }
  
    size_t getBufSize() const { return Buf.size(); }
  
  private:
    StringRef Buf;
  
    ELFFile(StringRef Object);
  
  public:
    const Elf_Ehdr &getHeader() const {
      return *reinterpret_cast<const Elf_Ehdr *>(base());
    }
  
    template <typename T>
    Expected<const T *> getEntry(uint32_t Section, uint32_t Entry) const;
    template <typename T>
    Expected<const T *> getEntry(const Elf_Shdr &Section, uint32_t Entry) const;
  
    Expected<std::vector<VerDef>>
    getVersionDefinitions(const Elf_Shdr &Sec) const;
    Expected<std::vector<VerNeed>> getVersionDependencies(
        const Elf_Shdr &Sec,
        WarningHandler WarnHandler = &defaultWarningHandler) const;
    Expected<StringRef>
    getSymbolVersionByIndex(uint32_t SymbolVersionIndex, bool &IsDefault,
                            SmallVector<Optional<VersionEntry>, 0> &VersionMap,
                            Optional<bool> IsSymHidden) const;
  
    Expected<StringRef>
    getStringTable(const Elf_Shdr &Section,
                   WarningHandler WarnHandler = &defaultWarningHandler) const;
    Expected<StringRef> getStringTableForSymtab(const Elf_Shdr &Section) const;
    Expected<StringRef> getStringTableForSymtab(const Elf_Shdr &Section,
                                                Elf_Shdr_Range Sections) const;
    Expected<StringRef> getLinkAsStrtab(const typename ELFT::Shdr &Sec) const;
  
    Expected<ArrayRef<Elf_Word>> getSHNDXTable(const Elf_Shdr &Section) const;
    Expected<ArrayRef<Elf_Word>> getSHNDXTable(const Elf_Shdr &Section,
                                               Elf_Shdr_Range Sections) const;
  
    Expected<uint64_t> getDynSymtabSize() const;
  
    StringRef getRelocationTypeName(uint32_t Type) const;
    void getRelocationTypeName(uint32_t Type,
                               SmallVectorImpl<char> &Result) const;
    uint32_t getRelativeRelocationType() const;
  
    std::string getDynamicTagAsString(unsigned Arch, uint64_t Type) const;
    std::string getDynamicTagAsString(uint64_t Type) const;
  
    /// Get the symbol for a given relocation.
    Expected<const Elf_Sym *> getRelocationSymbol(const Elf_Rel &Rel,
                                                  const Elf_Shdr *SymTab) const;
  
    Expected<SmallVector<Optional<VersionEntry>, 0>>
    loadVersionMap(const Elf_Shdr *VerNeedSec, const Elf_Shdr *VerDefSec) const;
  
    static Expected<ELFFile> create(StringRef Object);
  
    bool isLE() const {
      return getHeader().getDataEncoding() == ELF::ELFDATA2LSB;
    }
  
    bool isMipsELF64() const {
      return getHeader().e_machine == ELF::EM_MIPS &&
             getHeader().getFileClass() == ELF::ELFCLASS64;
    }
  
    bool isMips64EL() const { return isMipsELF64() && isLE(); }
  
    Expected<Elf_Shdr_Range> sections() const;
  
    Expected<Elf_Dyn_Range> dynamicEntries() const;
  
    Expected<const uint8_t *>
    toMappedAddr(uint64_t VAddr,
                 WarningHandler WarnHandler = &defaultWarningHandler) const;
  
    Expected<Elf_Sym_Range> symbols(const Elf_Shdr *Sec) const {
      if (!Sec)
        return makeArrayRef<Elf_Sym>(nullptr, nullptr);
      return getSectionContentsAsArray<Elf_Sym>(*Sec);
    }
  
    Expected<Elf_Rela_Range> relas(const Elf_Shdr &Sec) const {
      return getSectionContentsAsArray<Elf_Rela>(Sec);
    }
  
    Expected<Elf_Rel_Range> rels(const Elf_Shdr &Sec) const {
      return getSectionContentsAsArray<Elf_Rel>(Sec);
    }
  
    Expected<Elf_Relr_Range> relrs(const Elf_Shdr &Sec) const {
      return getSectionContentsAsArray<Elf_Relr>(Sec);
    }
  
    std::vector<Elf_Rel> decode_relrs(Elf_Relr_Range relrs) const;
  
    Expected<std::vector<Elf_Rela>> android_relas(const Elf_Shdr &Sec) const;
  
    /// Iterate over program header table.
    Expected<Elf_Phdr_Range> program_headers() const {
      if (getHeader().e_phnum && getHeader().e_phentsize != sizeof(Elf_Phdr))
        return createError("invalid e_phentsize: " +
                           Twine(getHeader().e_phentsize));
  
      uint64_t HeadersSize =
          (uint64_t)getHeader().e_phnum * getHeader().e_phentsize;
      uint64_t PhOff = getHeader().e_phoff;
      if (PhOff + HeadersSize < PhOff || PhOff + HeadersSize > getBufSize())
        return createError("program headers are longer than binary of size " +
                           Twine(getBufSize()) + ": e_phoff = 0x" +
                           Twine::utohexstr(getHeader().e_phoff) +
                           ", e_phnum = " + Twine(getHeader().e_phnum) +
                           ", e_phentsize = " + Twine(getHeader().e_phentsize));
  
      auto *Begin = reinterpret_cast<const Elf_Phdr *>(base() + PhOff);
      return makeArrayRef(Begin, Begin + getHeader().e_phnum);
    }
  
    /// Get an iterator over notes in a program header.
    ///
    /// The program header must be of type \c PT_NOTE.
    ///
    /// \param Phdr the program header to iterate over.
    /// \param Err [out] an error to support fallible iteration, which should
    ///  be checked after iteration ends.
    Elf_Note_Iterator notes_begin(const Elf_Phdr &Phdr, Error &Err) const {
      assert(Phdr.p_type == ELF::PT_NOTE && "Phdr is not of type PT_NOTE");
      ErrorAsOutParameter ErrAsOutParam(&Err);
      if (Phdr.p_offset + Phdr.p_filesz > getBufSize()) {
        Err =
            createError("invalid offset (0x" + Twine::utohexstr(Phdr.p_offset) +
                        ") or size (0x" + Twine::utohexstr(Phdr.p_filesz) + ")");
        return Elf_Note_Iterator(Err);
      }
      return Elf_Note_Iterator(base() + Phdr.p_offset, Phdr.p_filesz, Err);
    }
  
    /// Get an iterator over notes in a section.
    ///
    /// The section must be of type \c SHT_NOTE.
    ///
    /// \param Shdr the section to iterate over.
    /// \param Err [out] an error to support fallible iteration, which should
    ///  be checked after iteration ends.
    Elf_Note_Iterator notes_begin(const Elf_Shdr &Shdr, Error &Err) const {
      assert(Shdr.sh_type == ELF::SHT_NOTE && "Shdr is not of type SHT_NOTE");
      ErrorAsOutParameter ErrAsOutParam(&Err);
      if (Shdr.sh_offset + Shdr.sh_size > getBufSize()) {
        Err =
            createError("invalid offset (0x" + Twine::utohexstr(Shdr.sh_offset) +
                        ") or size (0x" + Twine::utohexstr(Shdr.sh_size) + ")");
        return Elf_Note_Iterator(Err);
      }
      return Elf_Note_Iterator(base() + Shdr.sh_offset, Shdr.sh_size, Err);
    }
  
    /// Get the end iterator for notes.
    Elf_Note_Iterator notes_end() const {
      return Elf_Note_Iterator();
    }
  
    /// Get an iterator range over notes of a program header.
    ///
    /// The program header must be of type \c PT_NOTE.
    ///
    /// \param Phdr the program header to iterate over.
    /// \param Err [out] an error to support fallible iteration, which should
    ///  be checked after iteration ends.
    iterator_range<Elf_Note_Iterator> notes(const Elf_Phdr &Phdr,
                                            Error &Err) const {
      return make_range(notes_begin(Phdr, Err), notes_end());
    }
  
    /// Get an iterator range over notes of a section.
    ///
    /// The section must be of type \c SHT_NOTE.
    ///
    /// \param Shdr the section to iterate over.
    /// \param Err [out] an error to support fallible iteration, which should
    ///  be checked after iteration ends.
    iterator_range<Elf_Note_Iterator> notes(const Elf_Shdr &Shdr,
                                            Error &Err) const {
      return make_range(notes_begin(Shdr, Err), notes_end());
    }
  
    Expected<StringRef> getSectionStringTable(
        Elf_Shdr_Range Sections,
        WarningHandler WarnHandler = &defaultWarningHandler) const;
    Expected<uint32_t> getSectionIndex(const Elf_Sym &Sym, Elf_Sym_Range Syms,
                                       DataRegion<Elf_Word> ShndxTable) const;
    Expected<const Elf_Shdr *> getSection(const Elf_Sym &Sym,
                                          const Elf_Shdr *SymTab,
                                          DataRegion<Elf_Word> ShndxTable) const;
    Expected<const Elf_Shdr *> getSection(const Elf_Sym &Sym,
                                          Elf_Sym_Range Symtab,
                                          DataRegion<Elf_Word> ShndxTable) const;
    Expected<const Elf_Shdr *> getSection(uint32_t Index) const;
  
    Expected<const Elf_Sym *> getSymbol(const Elf_Shdr *Sec,
                                        uint32_t Index) const;
  
    Expected<StringRef>
    getSectionName(const Elf_Shdr &Section,
                   WarningHandler WarnHandler = &defaultWarningHandler) const;
    Expected<StringRef> getSectionName(const Elf_Shdr &Section,
                                       StringRef DotShstrtab) const;
    template <typename T>
    Expected<ArrayRef<T>> getSectionContentsAsArray(const Elf_Shdr &Sec) const;
    Expected<ArrayRef<uint8_t>> getSectionContents(const Elf_Shdr &Sec) const;
    Expected<ArrayRef<uint8_t>> getSegmentContents(const Elf_Phdr &Phdr) const;
  };
  
  using ELF32LEFile = ELFFile<ELF32LE>;
  using ELF64LEFile = ELFFile<ELF64LE>;
  using ELF32BEFile = ELFFile<ELF32BE>;
  using ELF64BEFile = ELFFile<ELF64BE>;
  
  template <class ELFT>
  inline Expected<const typename ELFT::Shdr *>
  getSection(typename ELFT::ShdrRange Sections, uint32_t Index) {
    if (Index >= Sections.size())
      return createError("invalid section index: " + Twine(Index));
    return &Sections[Index];
  }
  
  template <class ELFT>
  inline Expected<uint32_t>
  getExtendedSymbolTableIndex(const typename ELFT::Sym &Sym, unsigned SymIndex,
                              DataRegion<typename ELFT::Word> ShndxTable) {
    assert(Sym.st_shndx == ELF::SHN_XINDEX);
    if (!ShndxTable.First)
      return createError(
          "found an extended symbol index (" + Twine(SymIndex) +
          "), but unable to locate the extended symbol index table");
  
    Expected<typename ELFT::Word> TableOrErr = ShndxTable[SymIndex];
    if (!TableOrErr)
      return createError("unable to read an extended symbol table at index " +
                         Twine(SymIndex) + ": " +
                         toString(TableOrErr.takeError()));
    return *TableOrErr;
  }
  
  template <class ELFT>
  Expected<uint32_t>
  ELFFile<ELFT>::getSectionIndex(const Elf_Sym &Sym, Elf_Sym_Range Syms,
                                 DataRegion<Elf_Word> ShndxTable) const {
    uint32_t Index = Sym.st_shndx;
    if (Index == ELF::SHN_XINDEX) {
      Expected<uint32_t> ErrorOrIndex =
          getExtendedSymbolTableIndex<ELFT>(Sym, &Sym - Syms.begin(), ShndxTable);
      if (!ErrorOrIndex)
        return ErrorOrIndex.takeError();
      return *ErrorOrIndex;
    }
    if (Index == ELF::SHN_UNDEF || Index >= ELF::SHN_LORESERVE)
      return 0;
    return Index;
  }
  
  template <class ELFT>
  Expected<const typename ELFT::Shdr *>
  ELFFile<ELFT>::getSection(const Elf_Sym &Sym, const Elf_Shdr *SymTab,
                            DataRegion<Elf_Word> ShndxTable) const {
    auto SymsOrErr = symbols(SymTab);
    if (!SymsOrErr)
      return SymsOrErr.takeError();
    return getSection(Sym, *SymsOrErr, ShndxTable);
  }
  
  template <class ELFT>
  Expected<const typename ELFT::Shdr *>
  ELFFile<ELFT>::getSection(const Elf_Sym &Sym, Elf_Sym_Range Symbols,
                            DataRegion<Elf_Word> ShndxTable) const {
    auto IndexOrErr = getSectionIndex(Sym, Symbols, ShndxTable);
    if (!IndexOrErr)
      return IndexOrErr.takeError();
    uint32_t Index = *IndexOrErr;
    if (Index == 0)
      return nullptr;
    return getSection(Index);
  }
  
  template <class ELFT>
  Expected<const typename ELFT::Sym *>
  ELFFile<ELFT>::getSymbol(const Elf_Shdr *Sec, uint32_t Index) const {
    auto SymsOrErr = symbols(Sec);
    if (!SymsOrErr)
      return SymsOrErr.takeError();
  
    Elf_Sym_Range Symbols = *SymsOrErr;
    if (Index >= Symbols.size())
      return createError("unable to get symbol from section " +
                         getSecIndexForError(*this, *Sec) +
                         ": invalid symbol index (" + Twine(Index) + ")");
    return &Symbols[Index];
  }
  
  template <class ELFT>
  template <typename T>
  Expected<ArrayRef<T>>
  ELFFile<ELFT>::getSectionContentsAsArray(const Elf_Shdr &Sec) const {
    if (Sec.sh_entsize != sizeof(T) && sizeof(T) != 1)
      return createError("section " + getSecIndexForError(*this, Sec) +
                         " has invalid sh_entsize: expected " + Twine(sizeof(T)) +
                         ", but got " + Twine(Sec.sh_entsize));
  
    uintX_t Offset = Sec.sh_offset;
    uintX_t Size = Sec.sh_size;
  
    if (Size % sizeof(T))
      return createError("section " + getSecIndexForError(*this, Sec) +
                         " has an invalid sh_size (" + Twine(Size) +
                         ") which is not a multiple of its sh_entsize (" +
                         Twine(Sec.sh_entsize) + ")");
    if (std::numeric_limits<uintX_t>::max() - Offset < Size)
      return createError("section " + getSecIndexForError(*this, Sec) +
                         " has a sh_offset (0x" + Twine::utohexstr(Offset) +
                         ") + sh_size (0x" + Twine::utohexstr(Size) +
                         ") that cannot be represented");
    if (Offset + Size > Buf.size())
      return createError("section " + getSecIndexForError(*this, Sec) +
                         " has a sh_offset (0x" + Twine::utohexstr(Offset) +
                         ") + sh_size (0x" + Twine::utohexstr(Size) +
                         ") that is greater than the file size (0x" +
                         Twine::utohexstr(Buf.size()) + ")");
  
    if (Offset % alignof(T))
      // TODO: this error is untested.
      return createError("unaligned data");
  
    const T *Start = reinterpret_cast<const T *>(base() + Offset);
    return makeArrayRef(Start, Size / sizeof(T));
  }
  
  template <class ELFT>
  Expected<ArrayRef<uint8_t>>
  ELFFile<ELFT>::getSegmentContents(const Elf_Phdr &Phdr) const {
    uintX_t Offset = Phdr.p_offset;
    uintX_t Size = Phdr.p_filesz;
  
    if (std::numeric_limits<uintX_t>::max() - Offset < Size)
      return createError("program header " + getPhdrIndexForError(*this, Phdr) +
                         " has a p_offset (0x" + Twine::utohexstr(Offset) +
                         ") + p_filesz (0x" + Twine::utohexstr(Size) +
                         ") that cannot be represented");
    if (Offset + Size > Buf.size())
      return createError("program header  " + getPhdrIndexForError(*this, Phdr) +
                         " has a p_offset (0x" + Twine::utohexstr(Offset) +
                         ") + p_filesz (0x" + Twine::utohexstr(Size) +
                         ") that is greater than the file size (0x" +
                         Twine::utohexstr(Buf.size()) + ")");
    return makeArrayRef(base() + Offset, Size);
  }
  
  template <class ELFT>
  Expected<ArrayRef<uint8_t>>
  ELFFile<ELFT>::getSectionContents(const Elf_Shdr &Sec) const {
    return getSectionContentsAsArray<uint8_t>(Sec);
  }
  
  template <class ELFT>
  StringRef ELFFile<ELFT>::getRelocationTypeName(uint32_t Type) const {
    return getELFRelocationTypeName(getHeader().e_machine, Type);
  }
  
  template <class ELFT>
  void ELFFile<ELFT>::getRelocationTypeName(uint32_t Type,
                                            SmallVectorImpl<char> &Result) const {
    if (!isMipsELF64()) {
      StringRef Name = getRelocationTypeName(Type);
      Result.append(Name.begin(), Name.end());
    } else {
      // The Mips N64 ABI allows up to three operations to be specified per
      // relocation record. Unfortunately there's no easy way to test for the
      // presence of N64 ELFs as they have no special flag that identifies them
      // as being N64. We can safely assume at the moment that all Mips
      // ELFCLASS64 ELFs are N64. New Mips64 ABIs should provide enough
      // information to disambiguate between old vs new ABIs.
      uint8_t Type1 = (Type >> 0) & 0xFF;
      uint8_t Type2 = (Type >> 8) & 0xFF;
      uint8_t Type3 = (Type >> 16) & 0xFF;
  
      // Concat all three relocation type names.
      StringRef Name = getRelocationTypeName(Type1);
      Result.append(Name.begin(), Name.end());
  
      Name = getRelocationTypeName(Type2);
      Result.append(1, '/');
      Result.append(Name.begin(), Name.end());
  
      Name = getRelocationTypeName(Type3);
      Result.append(1, '/');
      Result.append(Name.begin(), Name.end());
    }
  }
  
  template <class ELFT>
  uint32_t ELFFile<ELFT>::getRelativeRelocationType() const {
    return getELFRelativeRelocationType(getHeader().e_machine);
  }
  
  template <class ELFT>
  Expected<SmallVector<Optional<VersionEntry>, 0>>
  ELFFile<ELFT>::loadVersionMap(const Elf_Shdr *VerNeedSec,
                                const Elf_Shdr *VerDefSec) const {
    SmallVector<Optional<VersionEntry>, 0> VersionMap;
  
    // The first two version indexes are reserved.
    // Index 0 is VER_NDX_LOCAL, index 1 is VER_NDX_GLOBAL.
    VersionMap.push_back(VersionEntry());
    VersionMap.push_back(VersionEntry());
  
    auto InsertEntry = [&](unsigned N, StringRef Version, bool IsVerdef) {
      if (N >= VersionMap.size())
        VersionMap.resize(N + 1);
      VersionMap[N] = {std::string(Version), IsVerdef};
    };
  
    if (VerDefSec) {
      Expected<std::vector<VerDef>> Defs = getVersionDefinitions(*VerDefSec);
      if (!Defs)
        return Defs.takeError();
      for (const VerDef &Def : *Defs)
        InsertEntry(Def.Ndx & ELF::VERSYM_VERSION, Def.Name, true);
    }
  
    if (VerNeedSec) {
      Expected<std::vector<VerNeed>> Deps = getVersionDependencies(*VerNeedSec);
      if (!Deps)
        return Deps.takeError();
      for (const VerNeed &Dep : *Deps)
        for (const VernAux &Aux : Dep.AuxV)
          InsertEntry(Aux.Other & ELF::VERSYM_VERSION, Aux.Name, false);
    }
  
    return VersionMap;
  }
  
  template <class ELFT>
  Expected<const typename ELFT::Sym *>
  ELFFile<ELFT>::getRelocationSymbol(const Elf_Rel &Rel,
                                     const Elf_Shdr *SymTab) const {
    uint32_t Index = Rel.getSymbol(isMips64EL());
    if (Index == 0)
      return nullptr;
    return getEntry<Elf_Sym>(*SymTab, Index);
  }
  
  template <class ELFT>
  Expected<StringRef>
  ELFFile<ELFT>::getSectionStringTable(Elf_Shdr_Range Sections,
                                       WarningHandler WarnHandler) const {
    uint32_t Index = getHeader().e_shstrndx;
    if (Index == ELF::SHN_XINDEX) {
      // If the section name string table section index is greater than
      // or equal to SHN_LORESERVE, then the actual index of the section name
      // string table section is contained in the sh_link field of the section
      // header at index 0.
      if (Sections.empty())
        return createError(
            "e_shstrndx == SHN_XINDEX, but the section header table is empty");
  
      Index = Sections[0].sh_link;
    }
  
    if (!Index) // no section string table.
      return "";
    if (Index >= Sections.size())
      return createError("section header string table index " + Twine(Index) +
                         " does not exist");
    return getStringTable(Sections[Index], WarnHandler);
  }
  
  /// This function finds the number of dynamic symbols using a GNU hash table.
  ///
  /// @param Table The GNU hash table for .dynsym.
  template <class ELFT>
  static Expected<uint64_t>
  getDynSymtabSizeFromGnuHash(const typename ELFT::GnuHash &Table,
                              const void *BufEnd) {
    using Elf_Word = typename ELFT::Word;
    if (Table.nbuckets == 0)
      return Table.symndx + 1;
    uint64_t LastSymIdx = 0;
    // Find the index of the first symbol in the last chain.
    for (Elf_Word Val : Table.buckets())
      LastSymIdx = std::max(LastSymIdx, (uint64_t)Val);
    const Elf_Word *It =
        reinterpret_cast<const Elf_Word *>(Table.values(LastSymIdx).end());
    // Locate the end of the chain to find the last symbol index.
    while (It < BufEnd && (*It & 1) == 0) {
      ++LastSymIdx;
      ++It;
    }
    if (It >= BufEnd) {
      return createStringError(
          object_error::parse_failed,
          "no terminator found for GNU hash section before buffer end");
    }
    return LastSymIdx + 1;
  }
  
  /// This function determines the number of dynamic symbols. It reads section
  /// headers first. If section headers are not available, the number of
  /// symbols will be inferred by parsing dynamic hash tables.
  template <class ELFT>
  Expected<uint64_t> ELFFile<ELFT>::getDynSymtabSize() const {
    // Read .dynsym section header first if available.
    Expected<Elf_Shdr_Range> SectionsOrError = sections();
    if (!SectionsOrError)
      return SectionsOrError.takeError();
    for (const Elf_Shdr &Sec : *SectionsOrError) {
      if (Sec.sh_type == ELF::SHT_DYNSYM) {
        if (Sec.sh_size % Sec.sh_entsize != 0) {
          return createStringError(object_error::parse_failed,
                                   "SHT_DYNSYM section has sh_size (" +
                                       Twine(Sec.sh_size) + ") % sh_entsize (" +
                                       Twine(Sec.sh_entsize) + ") that is not 0");
        }
        return Sec.sh_size / Sec.sh_entsize;
      }
    }
  
    if (!SectionsOrError->empty()) {
      // Section headers are available but .dynsym header is not found.
      // Return 0 as .dynsym does not exist.
      return 0;
    }
  
    // Section headers do not exist. Falling back to infer
    // upper bound of .dynsym from .gnu.hash and .hash.
    Expected<Elf_Dyn_Range> DynTable = dynamicEntries();
    if (!DynTable)
      return DynTable.takeError();
    llvm::Optional<uint64_t> ElfHash;
    llvm::Optional<uint64_t> ElfGnuHash;
    for (const Elf_Dyn &Entry : *DynTable) {
      switch (Entry.d_tag) {
      case ELF::DT_HASH:
        ElfHash = Entry.d_un.d_ptr;
        break;
      case ELF::DT_GNU_HASH:
        ElfGnuHash = Entry.d_un.d_ptr;
        break;
      }
    }
    if (ElfGnuHash) {
      Expected<const uint8_t *> TablePtr = toMappedAddr(*ElfGnuHash);
      if (!TablePtr)
        return TablePtr.takeError();
      const Elf_GnuHash *Table =
          reinterpret_cast<const Elf_GnuHash *>(TablePtr.get());
      return getDynSymtabSizeFromGnuHash<ELFT>(*Table, this->Buf.bytes_end());
    }
  
    // Search SYSV hash table to try to find the upper bound of dynsym.
    if (ElfHash) {
      Expected<const uint8_t *> TablePtr = toMappedAddr(*ElfHash);
      if (!TablePtr)
        return TablePtr.takeError();
      const Elf_Hash *Table = reinterpret_cast<const Elf_Hash *>(TablePtr.get());
      return Table->nchain;
    }
    return 0;
  }
  
  template <class ELFT> ELFFile<ELFT>::ELFFile(StringRef Object) : Buf(Object) {}
  
  template <class ELFT>
  Expected<ELFFile<ELFT>> ELFFile<ELFT>::create(StringRef Object) {
    if (sizeof(Elf_Ehdr) > Object.size())
      return createError("invalid buffer: the size (" + Twine(Object.size()) +
                         ") is smaller than an ELF header (" +
                         Twine(sizeof(Elf_Ehdr)) + ")");
    return ELFFile(Object);
  }
  
  template <class ELFT>
  Expected<typename ELFT::ShdrRange> ELFFile<ELFT>::sections() const {
    const uintX_t SectionTableOffset = getHeader().e_shoff;
    if (SectionTableOffset == 0)
      return ArrayRef<Elf_Shdr>();
  
    if (getHeader().e_shentsize != sizeof(Elf_Shdr))
      return createError("invalid e_shentsize in ELF header: " +
                         Twine(getHeader().e_shentsize));
  
    const uint64_t FileSize = Buf.size();
    if (SectionTableOffset + sizeof(Elf_Shdr) > FileSize ||
        SectionTableOffset + (uintX_t)sizeof(Elf_Shdr) < SectionTableOffset)
      return createError(
          "section header table goes past the end of the file: e_shoff = 0x" +
          Twine::utohexstr(SectionTableOffset));
  
    // Invalid address alignment of section headers
    if (SectionTableOffset & (alignof(Elf_Shdr) - 1))
      // TODO: this error is untested.
      return createError("invalid alignment of section headers");
  
    const Elf_Shdr *First =
        reinterpret_cast<const Elf_Shdr *>(base() + SectionTableOffset);
  
    uintX_t NumSections = getHeader().e_shnum;
    if (NumSections == 0)
      NumSections = First->sh_size;
  
    if (NumSections > UINT64_MAX / sizeof(Elf_Shdr))
      return createError("invalid number of sections specified in the NULL "
                         "section's sh_size field (" +
                         Twine(NumSections) + ")");
  
    const uint64_t SectionTableSize = NumSections * sizeof(Elf_Shdr);
    if (SectionTableOffset + SectionTableSize < SectionTableOffset)
      return createError(
          "invalid section header table offset (e_shoff = 0x" +
          Twine::utohexstr(SectionTableOffset) +
          ") or invalid number of sections specified in the first section "
          "header's sh_size field (0x" +
          Twine::utohexstr(NumSections) + ")");
  
    // Section table goes past end of file!
    if (SectionTableOffset + SectionTableSize > FileSize)
      return createError("section table goes past the end of file");
    return makeArrayRef(First, NumSections);
  }
  
  template <class ELFT>
  template <typename T>
  Expected<const T *> ELFFile<ELFT>::getEntry(uint32_t Section,
                                              uint32_t Entry) const {
    auto SecOrErr = getSection(Section);
    if (!SecOrErr)
      return SecOrErr.takeError();
    return getEntry<T>(**SecOrErr, Entry);
  }
  
  template <class ELFT>
  template <typename T>
  Expected<const T *> ELFFile<ELFT>::getEntry(const Elf_Shdr &Section,
                                              uint32_t Entry) const {
    Expected<ArrayRef<T>> EntriesOrErr = getSectionContentsAsArray<T>(Section);
    if (!EntriesOrErr)
      return EntriesOrErr.takeError();
  
    ArrayRef<T> Arr = *EntriesOrErr;
    if (Entry >= Arr.size())
      return createError(
          "can't read an entry at 0x" +
          Twine::utohexstr(Entry * static_cast<uint64_t>(sizeof(T))) +
          ": it goes past the end of the section (0x" +
          Twine::utohexstr(Section.sh_size) + ")");
    return &Arr[Entry];
  }
  
  template <typename ELFT>
  Expected<StringRef> ELFFile<ELFT>::getSymbolVersionByIndex(
      uint32_t SymbolVersionIndex, bool &IsDefault,
      SmallVector<Optional<VersionEntry>, 0> &VersionMap,
      Optional<bool> IsSymHidden) const {
    size_t VersionIndex = SymbolVersionIndex & llvm::ELF::VERSYM_VERSION;
  
    // Special markers for unversioned symbols.
    if (VersionIndex == llvm::ELF::VER_NDX_LOCAL ||
        VersionIndex == llvm::ELF::VER_NDX_GLOBAL) {
      IsDefault = false;
      return "";
    }
  
    // Lookup this symbol in the version table.
    if (VersionIndex >= VersionMap.size() || !VersionMap[VersionIndex])
      return createError("SHT_GNU_versym section refers to a version index " +
                         Twine(VersionIndex) + " which is missing");
  
    const VersionEntry &Entry = *VersionMap[VersionIndex];
    // A default version (@@) is only available for defined symbols.
    if (!Entry.IsVerDef || IsSymHidden.getValueOr(false))
      IsDefault = false;
    else
      IsDefault = !(SymbolVersionIndex & llvm::ELF::VERSYM_HIDDEN);
    return Entry.Name.c_str();
  }
  
  template <class ELFT>
  Expected<std::vector<VerDef>>
  ELFFile<ELFT>::getVersionDefinitions(const Elf_Shdr &Sec) const {
    Expected<StringRef> StrTabOrErr = getLinkAsStrtab(Sec);
    if (!StrTabOrErr)
      return StrTabOrErr.takeError();
  
    Expected<ArrayRef<uint8_t>> ContentsOrErr = getSectionContents(Sec);
    if (!ContentsOrErr)
      return createError("cannot read content of " + describe(*this, Sec) + ": " +
                         toString(ContentsOrErr.takeError()));
  
    const uint8_t *Start = ContentsOrErr->data();
    const uint8_t *End = Start + ContentsOrErr->size();
  
    auto ExtractNextAux = [&](const uint8_t *&VerdauxBuf,
                              unsigned VerDefNdx) -> Expected<VerdAux> {
      if (VerdauxBuf + sizeof(Elf_Verdaux) > End)
        return createError("invalid " + describe(*this, Sec) +
                           ": version definition " + Twine(VerDefNdx) +
                           " refers to an auxiliary entry that goes past the end "
                           "of the section");
  
      auto *Verdaux = reinterpret_cast<const Elf_Verdaux *>(VerdauxBuf);
      VerdauxBuf += Verdaux->vda_next;
  
      VerdAux Aux;
      Aux.Offset = VerdauxBuf - Start;
      if (Verdaux->vda_name <= StrTabOrErr->size())
        Aux.Name = std::string(StrTabOrErr->drop_front(Verdaux->vda_name));
      else
        Aux.Name = ("<invalid vda_name: " + Twine(Verdaux->vda_name) + ">").str();
      return Aux;
    };
  
    std::vector<VerDef> Ret;
    const uint8_t *VerdefBuf = Start;
    for (unsigned I = 1; I <= /*VerDefsNum=*/Sec.sh_info; ++I) {
      if (VerdefBuf + sizeof(Elf_Verdef) > End)
        return createError("invalid " + describe(*this, Sec) +
                           ": version definition " + Twine(I) +
                           " goes past the end of the section");
  
      if (reinterpret_cast<uintptr_t>(VerdefBuf) % sizeof(uint32_t) != 0)
        return createError(
            "invalid " + describe(*this, Sec) +
            ": found a misaligned version definition entry at offset 0x" +
            Twine::utohexstr(VerdefBuf - Start));
  
      unsigned Version = *reinterpret_cast<const Elf_Half *>(VerdefBuf);
      if (Version != 1)
        return createError("unable to dump " + describe(*this, Sec) +
                           ": version " + Twine(Version) +
                           " is not yet supported");
  
      const Elf_Verdef *D = reinterpret_cast<const Elf_Verdef *>(VerdefBuf);
      VerDef &VD = *Ret.emplace(Ret.end());
      VD.Offset = VerdefBuf - Start;
      VD.Version = D->vd_version;
      VD.Flags = D->vd_flags;
      VD.Ndx = D->vd_ndx;
      VD.Cnt = D->vd_cnt;
      VD.Hash = D->vd_hash;
  
      const uint8_t *VerdauxBuf = VerdefBuf + D->vd_aux;
      for (unsigned J = 0; J < D->vd_cnt; ++J) {
        if (reinterpret_cast<uintptr_t>(VerdauxBuf) % sizeof(uint32_t) != 0)
          return createError("invalid " + describe(*this, Sec) +
                             ": found a misaligned auxiliary entry at offset 0x" +
                             Twine::utohexstr(VerdauxBuf - Start));
  
        Expected<VerdAux> AuxOrErr = ExtractNextAux(VerdauxBuf, I);
        if (!AuxOrErr)
          return AuxOrErr.takeError();
  
        if (J == 0)
          VD.Name = AuxOrErr->Name;
        else
          VD.AuxV.push_back(*AuxOrErr);
      }
  
      VerdefBuf += D->vd_next;
    }
  
    return Ret;
  }
  
  template <class ELFT>
  Expected<std::vector<VerNeed>>
  ELFFile<ELFT>::getVersionDependencies(const Elf_Shdr &Sec,
                                        WarningHandler WarnHandler) const {
    StringRef StrTab;
    Expected<StringRef> StrTabOrErr = getLinkAsStrtab(Sec);
    if (!StrTabOrErr) {
      if (Error E = WarnHandler(toString(StrTabOrErr.takeError())))
        return std::move(E);
    } else {
      StrTab = *StrTabOrErr;
    }
  
    Expected<ArrayRef<uint8_t>> ContentsOrErr = getSectionContents(Sec);
    if (!ContentsOrErr)
      return createError("cannot read content of " + describe(*this, Sec) + ": " +
                         toString(ContentsOrErr.takeError()));
  
    const uint8_t *Start = ContentsOrErr->data();
    const uint8_t *End = Start + ContentsOrErr->size();
    const uint8_t *VerneedBuf = Start;
  
    std::vector<VerNeed> Ret;
    for (unsigned I = 1; I <= /*VerneedNum=*/Sec.sh_info; ++I) {
      if (VerneedBuf + sizeof(Elf_Verdef) > End)
        return createError("invalid " + describe(*this, Sec) +
                           ": version dependency " + Twine(I) +
                           " goes past the end of the section");
  
      if (reinterpret_cast<uintptr_t>(VerneedBuf) % sizeof(uint32_t) != 0)
        return createError(
            "invalid " + describe(*this, Sec) +
            ": found a misaligned version dependency entry at offset 0x" +
            Twine::utohexstr(VerneedBuf - Start));
  
      unsigned Version = *reinterpret_cast<const Elf_Half *>(VerneedBuf);
      if (Version != 1)
        return createError("unable to dump " + describe(*this, Sec) +
                           ": version " + Twine(Version) +
                           " is not yet supported");
  
      const Elf_Verneed *Verneed =
          reinterpret_cast<const Elf_Verneed *>(VerneedBuf);
  
      VerNeed &VN = *Ret.emplace(Ret.end());
      VN.Version = Verneed->vn_version;
      VN.Cnt = Verneed->vn_cnt;
      VN.Offset = VerneedBuf - Start;
  
      if (Verneed->vn_file < StrTab.size())
        VN.File = std::string(StrTab.drop_front(Verneed->vn_file));
      else
        VN.File = ("<corrupt vn_file: " + Twine(Verneed->vn_file) + ">").str();
  
      const uint8_t *VernauxBuf = VerneedBuf + Verneed->vn_aux;
      for (unsigned J = 0; J < Verneed->vn_cnt; ++J) {
        if (reinterpret_cast<uintptr_t>(VernauxBuf) % sizeof(uint32_t) != 0)
          return createError("invalid " + describe(*this, Sec) +
                             ": found a misaligned auxiliary entry at offset 0x" +
                             Twine::utohexstr(VernauxBuf - Start));
  
        if (VernauxBuf + sizeof(Elf_Vernaux) > End)
          return createError(
              "invalid " + describe(*this, Sec) + ": version dependency " +
              Twine(I) +
              " refers to an auxiliary entry that goes past the end "
              "of the section");
  
        const Elf_Vernaux *Vernaux =
            reinterpret_cast<const Elf_Vernaux *>(VernauxBuf);
  
        VernAux &Aux = *VN.AuxV.emplace(VN.AuxV.end());
        Aux.Hash = Vernaux->vna_hash;
        Aux.Flags = Vernaux->vna_flags;
        Aux.Other = Vernaux->vna_other;
        Aux.Offset = VernauxBuf - Start;
        if (StrTab.size() <= Vernaux->vna_name)
          Aux.Name = "<corrupt>";
        else
          Aux.Name = std::string(StrTab.drop_front(Vernaux->vna_name));
  
        VernauxBuf += Vernaux->vna_next;
      }
      VerneedBuf += Verneed->vn_next;
    }
    return Ret;
  }
  
  template <class ELFT>
  Expected<const typename ELFT::Shdr *>
  ELFFile<ELFT>::getSection(uint32_t Index) const {
    auto TableOrErr = sections();
    if (!TableOrErr)
      return TableOrErr.takeError();
    return object::getSection<ELFT>(*TableOrErr, Index);
  }
  
  template <class ELFT>
  Expected<StringRef>
  ELFFile<ELFT>::getStringTable(const Elf_Shdr &Section,
                                WarningHandler WarnHandler) const {
    if (Section.sh_type != ELF::SHT_STRTAB)
      if (Error E = WarnHandler("invalid sh_type for string table section " +
                                getSecIndexForError(*this, Section) +
                                ": expected SHT_STRTAB, but got " +
                                object::getELFSectionTypeName(
                                    getHeader().e_machine, Section.sh_type)))
        return std::move(E);
  
    auto V = getSectionContentsAsArray<char>(Section);
    if (!V)
      return V.takeError();
    ArrayRef<char> Data = *V;
    if (Data.empty())
      return createError("SHT_STRTAB string table section " +
                         getSecIndexForError(*this, Section) + " is empty");
    if (Data.back() != '\0')
      return createError("SHT_STRTAB string table section " +
                         getSecIndexForError(*this, Section) +
                         " is non-null terminated");
    return StringRef(Data.begin(), Data.size());
  }
  
  template <class ELFT>
  Expected<ArrayRef<typename ELFT::Word>>
  ELFFile<ELFT>::getSHNDXTable(const Elf_Shdr &Section) const {
    auto SectionsOrErr = sections();
    if (!SectionsOrErr)
      return SectionsOrErr.takeError();
    return getSHNDXTable(Section, *SectionsOrErr);
  }
  
  template <class ELFT>
  Expected<ArrayRef<typename ELFT::Word>>
  ELFFile<ELFT>::getSHNDXTable(const Elf_Shdr &Section,
                               Elf_Shdr_Range Sections) const {
    assert(Section.sh_type == ELF::SHT_SYMTAB_SHNDX);
    auto VOrErr = getSectionContentsAsArray<Elf_Word>(Section);
    if (!VOrErr)
      return VOrErr.takeError();
    ArrayRef<Elf_Word> V = *VOrErr;
    auto SymTableOrErr = object::getSection<ELFT>(Sections, Section.sh_link);
    if (!SymTableOrErr)
      return SymTableOrErr.takeError();
    const Elf_Shdr &SymTable = **SymTableOrErr;
    if (SymTable.sh_type != ELF::SHT_SYMTAB &&
        SymTable.sh_type != ELF::SHT_DYNSYM)
      return createError(
          "SHT_SYMTAB_SHNDX section is linked with " +
          object::getELFSectionTypeName(getHeader().e_machine, SymTable.sh_type) +
          " section (expected SHT_SYMTAB/SHT_DYNSYM)");
  
    uint64_t Syms = SymTable.sh_size / sizeof(Elf_Sym);
    if (V.size() != Syms)
      return createError("SHT_SYMTAB_SHNDX has " + Twine(V.size()) +
                         " entries, but the symbol table associated has " +
                         Twine(Syms));
  
    return V;
  }
  
  template <class ELFT>
  Expected<StringRef>
  ELFFile<ELFT>::getStringTableForSymtab(const Elf_Shdr &Sec) const {
    auto SectionsOrErr = sections();
    if (!SectionsOrErr)
      return SectionsOrErr.takeError();
    return getStringTableForSymtab(Sec, *SectionsOrErr);
  }
  
  template <class ELFT>
  Expected<StringRef>
  ELFFile<ELFT>::getStringTableForSymtab(const Elf_Shdr &Sec,
                                         Elf_Shdr_Range Sections) const {
  
    if (Sec.sh_type != ELF::SHT_SYMTAB && Sec.sh_type != ELF::SHT_DYNSYM)
      return createError(
          "invalid sh_type for symbol table, expected SHT_SYMTAB or SHT_DYNSYM");
    Expected<const Elf_Shdr *> SectionOrErr =
        object::getSection<ELFT>(Sections, Sec.sh_link);
    if (!SectionOrErr)
      return SectionOrErr.takeError();
    return getStringTable(**SectionOrErr);
  }
  
  template <class ELFT>
  Expected<StringRef>
  ELFFile<ELFT>::getLinkAsStrtab(const typename ELFT::Shdr &Sec) const {
    Expected<const typename ELFT::Shdr *> StrTabSecOrErr =
        getSection(Sec.sh_link);
    if (!StrTabSecOrErr)
      return createError("invalid section linked to " + describe(*this, Sec) +
                         ": " + toString(StrTabSecOrErr.takeError()));
  
    Expected<StringRef> StrTabOrErr = getStringTable(**StrTabSecOrErr);
    if (!StrTabOrErr)
      return createError("invalid string table linked to " +
                         describe(*this, Sec) + ": " +
                         toString(StrTabOrErr.takeError()));
    return *StrTabOrErr;
  }
  
  template <class ELFT>
  Expected<StringRef>
  ELFFile<ELFT>::getSectionName(const Elf_Shdr &Section,
                                WarningHandler WarnHandler) const {
    auto SectionsOrErr = sections();
    if (!SectionsOrErr)
      return SectionsOrErr.takeError();
    auto Table = getSectionStringTable(*SectionsOrErr, WarnHandler);
    if (!Table)
      return Table.takeError();
    return getSectionName(Section, *Table);
  }
  
  template <class ELFT>
  Expected<StringRef> ELFFile<ELFT>::getSectionName(const Elf_Shdr &Section,
                                                    StringRef DotShstrtab) const {
    uint32_t Offset = Section.sh_name;
    if (Offset == 0)
      return StringRef();
    if (Offset >= DotShstrtab.size())
      return createError("a section " + getSecIndexForError(*this, Section) +
                         " has an invalid sh_name (0x" +
                         Twine::utohexstr(Offset) +
                         ") offset which goes past the end of the "
                         "section name string table");
    return StringRef(DotShstrtab.data() + Offset);
  }
  
  /// This function returns the hash value for a symbol in the .dynsym section
  /// Name of the API remains consistent as specified in the libelf
  /// REF : http://www.sco.com/developers/gabi/latest/ch5.dynamic.html#hash
  inline unsigned hashSysV(StringRef SymbolName) {
    unsigned h = 0, g;
    for (char C : SymbolName) {
      h = (h << 4) + C;
      g = h & 0xf0000000L;
      if (g != 0)
        h ^= g >> 24;
      h &= ~g;
    }
    return h;
  }
  
  } // end namespace object
  } // end namespace llvm
  
  #endif // LLVM_OBJECT_ELF_H
  