[PATCH] [Object/ELF] Provide symbol helpers

[Rui Ueyama]

All these member functions don't seem to actually belong to ELFFile. They
just call member functions of their arguments. Does it make more sense if
we add them to Elf_Sym?

On Thu, Jun 4, 2015 at 5:32 PM, Davide Italiano <dccitaliano at gmail.com>
wrote:

> Hi ruiu, rafael, shankar.easwaran,
>
> These were in lld. They can be reused for other tools, e.g. llvm-readobj.
> If needed, we can introduce another class as COFF does (i.e. COFFSymboRef).
> Note: Hexagon has a different notion of common symbol I'm not entirely
> sure I understand.
> I wasn't able to find documentation either, so any help on this side is
> greatly appreciated.
>
> REPOSITORY
>   rL LLVM
>
> http://reviews.llvm.org/D10264
>
> Files:
>   include/llvm/Object/ELF.h
>
> Index: include/llvm/Object/ELF.h
> ===================================================================
> --- include/llvm/Object/ELF.h
> +++ include/llvm/Object/ELF.h
> @@ -421,6 +421,11 @@
>    uint64_t getSymbolIndex(const Elf_Sym *sym) const;
>    ErrorOr<ArrayRef<uint8_t> > getSectionContents(const Elf_Shdr *Sec)
> const;
>    StringRef getLoadName() const;
> +
> +  bool isUndefinedSymbol(const Elf_Sym *Sym) const;
> +  bool isAbsoluteSymbol(const Elf_Sym *Sym) const;
> +  bool isCommonSymbol(const Elf_Sym *Sym) const;
> +  bool isDefinedSymbol(const Elf_Sym *Sym) const;
>  };
>
>  typedef ELFFile<ELFType<support::little, false>> ELF32LEFile;
> @@ -1010,6 +1015,39 @@
>    return StringRef(getDynamicString(name_offset));
>  }
>
> +template <class ELFT>
> +bool ELFFile<ELFT>::isUndefinedSymbol(const Elf_Sym *Sym) const {
> +  return Sym->st_shndx == llvm::ELF::SHN_UNDEF;
> +}
> +
> +template <class ELFT>
> +bool ELFFile<ELFT>::isAbsoluteSymbol(const Elf_Sym *Sym) const {
> +  return Sym->st_shndx == llvm::ELF::SHN_ABS;
> +}
> +
> +template <class ELFT>
> +bool ELFFile<ELFT>::isCommonSymbol(const Elf_Sym *Sym) const {
> +  return Sym->getType() == llvm::ELF::STT_COMMON ||
> +         Sym->st_shndx == llvm::ELF::SHN_COMMON ||
> +         /* Hexagon-specific */
> +         Sym->st_shndx == llvm::ELF::SHN_HEXAGON_SCOMMON ||
> +         Sym->st_shndx == llvm::ELF::SHN_HEXAGON_SCOMMON_1 ||
> +         Sym->st_shndx == llvm::ELF::SHN_HEXAGON_SCOMMON_2 ||
> +         Sym->st_shndx == llvm::ELF::SHN_HEXAGON_SCOMMON_4 ||
> +         Sym->st_shndx == llvm::ELF::SHN_HEXAGON_SCOMMON_8;
> +}
> +
> +template <class ELFT>
> +bool ELFFile<ELFT>::isDefinedSymbol(const Elf_Sym *Sym) const {
> +  return Sym->getType() == llvm::ELF::STT_NOTYPE ||
> +         Sym->getType() == llvm::ELF::STT_OBJECT ||
> +         Sym->getType() == llvm::ELF::STT_FUNC ||
> +         Sym->getType() == llvm::ELF::STT_GNU_IFUNC ||
> +         Sym->getType() == llvm::ELF::STT_SECTION ||
> +         Sym->getType() == llvm::ELF::STT_FILE ||
> +         Sym->getType() == llvm::ELF::STT_TLS;
> +}
> +
>  /// 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
>
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>
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