C++ SymbolBody::symbol方法代码示例

static typename ELFT::uint getSymVA(const SymbolBody &Body,
                                    typename ELFT::uint &Addend) {
  typedef typename ELFT::uint uintX_t;

  switch (Body.kind()) {
  case SymbolBody::DefinedSyntheticKind: {
    auto &D = cast<DefinedSynthetic<ELFT>>(Body);
    const OutputSectionBase<ELFT> *Sec = D.Section;
    if (!Sec)
      return D.Value;
    if (D.Value == DefinedSynthetic<ELFT>::SectionEnd)
      return Sec->getVA() + Sec->getSize();
    return Sec->getVA() + D.Value;
  }
  case SymbolBody::DefinedRegularKind: {
    auto &D = cast<DefinedRegular<ELFT>>(Body);
    InputSectionBase<ELFT> *SC = D.Section;

    // According to the ELF spec reference to a local symbol from outside
    // the group are not allowed. Unfortunately .eh_frame breaks that rule
    // and must be treated specially. For now we just replace the symbol with
    // 0.
    if (SC == &InputSection<ELFT>::Discarded)
      return 0;

    // This is an absolute symbol.
    if (!SC)
      return D.Value;

    uintX_t Offset = D.Value;
    if (D.isSection()) {
      Offset += Addend;
      Addend = 0;
    }
    uintX_t VA = SC->OutSec->getVA() + SC->getOffset(Offset);
    if (D.isTls())
      return VA - Out<ELFT>::TlsPhdr->p_vaddr;
    return VA;
  }
  case SymbolBody::DefinedCommonKind:
    return Out<ELFT>::Bss->getVA() + cast<DefinedCommon>(Body).OffsetInBss;
  case SymbolBody::SharedKind: {
    auto &SS = cast<SharedSymbol<ELFT>>(Body);
    if (!SS.NeedsCopyOrPltAddr)
      return 0;
    if (SS.isFunc())
      return Body.getPltVA<ELFT>();
    return Out<ELFT>::Bss->getVA() + SS.OffsetInBss;
  }
  case SymbolBody::UndefinedKind:
    return 0;
  case SymbolBody::LazyArchiveKind:
  case SymbolBody::LazyObjectKind:
    assert(Body.symbol()->IsUsedInRegularObj && "lazy symbol reached writer");
    return 0;
  case SymbolBody::DefinedBitcodeKind:
    llvm_unreachable("should have been replaced");
  }
  llvm_unreachable("invalid symbol kind");
}

// Rename SYM as __wrap_SYM. The original symbol is preserved as __real_SYM.
// Used to implement --wrap.
template <class ELFT> void SymbolTable<ELFT>::wrap(StringRef Name) {
  SymbolBody *B = find(Name);
  if (!B)
    return;
  StringSaver Saver(Alloc);
  Symbol *Sym = B->symbol();
  Symbol *Real = addUndefined(Saver.save("__real_" + Name));
  Symbol *Wrap = addUndefined(Saver.save("__wrap_" + Name));
  // We rename symbols by replacing the old symbol's SymbolBody with the new
  // symbol's SymbolBody. This causes all SymbolBody pointers referring to the
  // old symbol to instead refer to the new symbol.
  memcpy(Real->Body.buffer, Sym->Body.buffer, sizeof(Sym->Body));
  memcpy(Sym->Body.buffer, Wrap->Body.buffer, sizeof(Wrap->Body));
}

static typename ELFT::uint getSymVA(const SymbolBody &Body,
                                    typename ELFT::uint &Addend) {
  typedef typename ELFT::uint uintX_t;

  switch (Body.kind()) {
  case SymbolBody::DefinedSyntheticKind: {
    auto &D = cast<DefinedSynthetic>(Body);
    const OutputSectionBase *Sec = D.Section;
    if (!Sec)
      return D.Value;
    if (D.Value == uintX_t(-1))
      return Sec->Addr + Sec->Size;
    return Sec->Addr + D.Value;
  }
  case SymbolBody::DefinedRegularKind: {
    auto &D = cast<DefinedRegular<ELFT>>(Body);
    InputSectionBase<ELFT> *IS = D.Section;

    // According to the ELF spec reference to a local symbol from outside
    // the group are not allowed. Unfortunately .eh_frame breaks that rule
    // and must be treated specially. For now we just replace the symbol with
    // 0.
    if (IS == &InputSection<ELFT>::Discarded)
      return 0;

    // This is an absolute symbol.
    if (!IS)
      return D.Value;

    uintX_t Offset = D.Value;
    if (D.isSection()) {
      Offset += Addend;
      Addend = 0;
    }
    uintX_t VA = (IS->OutSec ? IS->OutSec->Addr : 0) + IS->getOffset(Offset);
    if (D.isTls() && !Config->Relocatable) {
      if (!Out<ELFT>::TlsPhdr)
        fatal(toString(D.File) +
              " has a STT_TLS symbol but doesn't have a PT_TLS section");
      return VA - Out<ELFT>::TlsPhdr->p_vaddr;
    }
    return VA;
  }
  case SymbolBody::DefinedCommonKind:
    if (!Config->DefineCommon)
      return 0;
    return In<ELFT>::Common->OutSec->Addr + In<ELFT>::Common->OutSecOff +
           cast<DefinedCommon>(Body).Offset;
  case SymbolBody::SharedKind: {
    auto &SS = cast<SharedSymbol<ELFT>>(Body);
    if (!SS.NeedsCopyOrPltAddr)
      return 0;
    if (SS.isFunc())
      return Body.getPltVA<ELFT>();
    return SS.getBssSectionForCopy()->Addr + SS.CopyOffset;
  }
  case SymbolBody::UndefinedKind:
    return 0;
  case SymbolBody::LazyArchiveKind:
  case SymbolBody::LazyObjectKind:
    assert(Body.symbol()->IsUsedInRegularObj && "lazy symbol reached writer");
    return 0;
  }
  llvm_unreachable("invalid symbol kind");
}