[llvm-objcopy] Replace the size() helper with SectionTableRef::size

[MaskRay]

Summary

BTW, STLExtras.h provides llvm::size() which is similar to std::size()
for random access iterators. However, if we prefer qualified
llvm::size(), the member function .size() will be more convenient.

[MaskRay]

.

[grimar]

LGTM

tools/llvm-objcopy/ELF/Object.h

public:
   using iterator = pointee_iterator<std::unique_ptr<SectionBase> *>;
 
   explicit SectionTableRef(MutableArrayRef<std::unique_ptr<SectionBase>> Secs)
       : Sections(Secs) {}
   SectionTableRef(const SectionTableRef &) = default;
 
   iterator begin() { return iterator(Sections.data()); }
   iterator end() { return iterator(Sections.data() + Sections.size()); }
+  size_t size() const { return Sections.size(); }
 
   SectionBase *getSection(uint32_t Index, Twine ErrMsg);
 
   template <class T>
   T *getSectionOfType(uint32_t Index, Twine IndexErrMsg, Twine TypeErrMsg);
 };
 
 enum ElfType { ELFT_ELF32LE, ELFT_ELF64LE, ELFT_ELF32BE, ELFT_ELF64BE };

tools/llvm-objcopy/ELF/Object.cpp

Obj.SectionNames =
       Obj.sections().template getSectionOfType<StringTableSection>(
           ShstrIndex,
           "e_shstrndx field value " + Twine(Ehdr.e_shstrndx) +
               " in elf header " + " is invalid",
           "e_shstrndx field value " + Twine(Ehdr.e_shstrndx) +
               " in elf header " + " is not a string table");
 }
 
-// A generic size function which computes sizes of any random access range.
-template <class R> size_t size(R &&Range) {
-  return static_cast<size_t>(std::end(Range) - std::begin(Range));
-}
-
 Writer::~Writer() {}
 
 Reader::~Reader() {}
 
 std::unique_ptr<Object> BinaryReader::create() const {
   return BinaryELFBuilder(MInfo.EMachine, MemBuf).build();
 }
 
template <class ELFT> void ELFWriter<ELFT>::writeEhdr() {
   Ehdr.e_entry = Obj.Entry;
   // We have to use the fully-qualified name llvm::size
   // since some compilers complain on ambiguous resolution.
   Ehdr.e_phnum = llvm::size(Obj.segments());
   Ehdr.e_phoff = (Ehdr.e_phnum != 0) ? Obj.ProgramHdrSegment.Offset : 0;
   Ehdr.e_phentsize = (Ehdr.e_phnum != 0) ? sizeof(Elf_Phdr) : 0;
   Ehdr.e_flags = Obj.Flags;
   Ehdr.e_ehsize = sizeof(Elf_Ehdr);
-  if (WriteSectionHeaders && size(Obj.sections()) != 0) {
+  if (WriteSectionHeaders && Obj.sections().size() != 0) {
     Ehdr.e_shentsize = sizeof(Elf_Shdr);
     Ehdr.e_shoff = Obj.SHOffset;
     // """
     // If the number of sections is greater than or equal to
     // SHN_LORESERVE (0xff00), this member has the value zero and the actual
     // number of section header table entries is contained in the sh_size field
     // of the section header at index 0.
     // """
-    auto Shnum = size(Obj.sections()) + 1;
+    auto Shnum = Obj.sections().size() + 1;
     if (Shnum >= SHN_LORESERVE)
       Ehdr.e_shnum = 0;
     else
       Ehdr.e_shnum = Shnum;
     // """
     // If the section name string table section index is greater than or equal
     // to SHN_LORESERVE (0xff00), this member has the value SHN_XINDEX (0xffff)
     // and the actual index of the section name string table section is
template <class ELFT> void ELFWriter<ELFT>::writeShdrs() {
   // of the file. It is not used for anything else
   Elf_Shdr &Shdr = *reinterpret_cast<Elf_Shdr *>(B);
   Shdr.sh_name = 0;
   Shdr.sh_type = SHT_NULL;
   Shdr.sh_flags = 0;
   Shdr.sh_addr = 0;
   Shdr.sh_offset = 0;
   // See writeEhdr for why we do this.
-  uint64_t Shnum = size(Obj.sections()) + 1;
+  uint64_t Shnum = Obj.sections().size() + 1;
   if (Shnum >= SHN_LORESERVE)
     Shdr.sh_size = Shnum;
   else
     Shdr.sh_size = 0;
   // See writeEhdr for why we do this.
   if (Obj.SectionNames != nullptr && Obj.SectionNames->Index >= SHN_LORESERVE)
     Shdr.sh_link = Obj.SectionNames->Index;
   else
if (WriteSectionHeaders)
     Offset = alignTo(Offset, sizeof(Elf_Addr));
   Obj.SHOffset = Offset;
 }
 
 template <class ELFT> size_t ELFWriter<ELFT>::totalSize() const {
   // We already have the section header offset so we can calculate the total
   // size by just adding up the size of each section header.
   auto NullSectionSize = WriteSectionHeaders ? sizeof(Elf_Shdr) : 0;
-  return Obj.SHOffset + size(Obj.sections()) * sizeof(Elf_Shdr) +
+  return Obj.SHOffset + Obj.sections().size() * sizeof(Elf_Shdr) +
          NullSectionSize;
 }
 
 template <class ELFT> Error ELFWriter<ELFT>::write() {
   // Segment data must be written first, so that the ELF header and program
   // header tables can overwrite it, if covered by a segment.
   writeSegmentData();
   writeEhdr();
return createStringError(llvm::errc::invalid_argument,
                              "section header string table was removed.");
 
   Obj.sortSections();
 
   // We need to assign indexes before we perform layout because we need to know
   // if we need large indexes or not. We can assign indexes first and check as
   // we go to see if we will actully need large indexes.
   bool NeedsLargeIndexes = false;
-  if (size(Obj.sections()) >= SHN_LORESERVE) {
+  if (Obj.sections().size() >= SHN_LORESERVE) {
     auto Sections = Obj.sections();
     NeedsLargeIndexes =
         std::any_of(Sections.begin() + SHN_LORESERVE, Sections.end(),
                     [](const SectionBase &Sec) { return Sec.HasSymbol; });
     // TODO: handle case where only one section needs the large index table but
     // only needs it because the large index table hasn't been removed yet.
   }