[NFC] refactor XCOFFObjectFile::getImportFileTable.

[DiggerLin]

Summary

1.refactor with XCOFFObjectFile::getImportFileTable with function getSectionFileOffsetToRawData instead of getLoaderSectionAddress

2. delete the function getLoaderSectionAddress.

[jhenderson]

Looks good, thanks!

You mentioned in another ticket that using the new function could cause other error paths to be hit. That's fine, and I don't think you need to specifically test them for the new type that uses the function, but it does mean that this ticket isn't technically a [NFC] so shouldn't be labelled as such. You could say why it isn't NFC in the commit body, to explain why you haven't added additional testing, for example, if you want.

[Esme]

LGTM. Thx!

llvm/include/llvm/Object/XCOFFObjectFile.h

private:
 
   size_t getFileHeaderSize() const;
   size_t getSectionHeaderSize() const;
 
   const XCOFFSectionHeader32 *toSection32(DataRefImpl Ref) const;
   const XCOFFSectionHeader64 *toSection64(DataRefImpl Ref) const;
   uintptr_t getSectionHeaderTableAddress() const;
   uintptr_t getEndOfSymbolTableAddress() const;
-  Expected<uintptr_t> getLoaderSectionAddress() const;
 
   DataRefImpl getSectionByType(XCOFF::SectionTypeFlags SectType) const;
   uint64_t getSectionFileOffsetToRawData(DataRefImpl Sec) const;
   Expected<uintptr_t>
   getSectionFileOffsetToRawData(XCOFF::SectionTypeFlags SectType) const;
 
   // This returns a pointer to the start of the storage for the name field of
   // the 32-bit or 64-bit SectionHeader struct. This string is *not* necessarily

llvm/lib/Object/XCOFFObjectFile.cpp

 
 uint64_t XCOFFObjectFile::getSectionFileOffsetToRawData(DataRefImpl Sec) const {
   if (is64Bit())
     return toSection64(Sec)->FileOffsetToRawData;
 
   return toSection32(Sec)->FileOffsetToRawData;
 }
 
-Expected<uintptr_t> XCOFFObjectFile::getLoaderSectionAddress() const {
-  uint64_t OffsetToLoaderSection = 0;
-  uint64_t SizeOfLoaderSection = 0;
-
-  if (is64Bit()) {
-    for (const auto &Sec64 : sections64())
-      if (Sec64.getSectionType() == XCOFF::STYP_LOADER) {
-        OffsetToLoaderSection = Sec64.FileOffsetToRawData;
-        SizeOfLoaderSection = Sec64.SectionSize;
-        break;
-      }
-  } else {
-    for (const auto &Sec32 : sections32())
-      if (Sec32.getSectionType() == XCOFF::STYP_LOADER) {
-        OffsetToLoaderSection = Sec32.FileOffsetToRawData;
-        SizeOfLoaderSection = Sec32.SectionSize;
-        break;
-      }
-  }
-
-  // No loader section is not an error.
-  if (!SizeOfLoaderSection)
-    return 0;
-
-  uintptr_t LoderSectionStart =
-      reinterpret_cast<uintptr_t>(base() + OffsetToLoaderSection);
-  if (Error E =
-          Binary::checkOffset(Data, LoderSectionStart, SizeOfLoaderSection))
-    return createError(toString(std::move(E)) +
-                       ": loader section with offset 0x" +
-                       Twine::utohexstr(OffsetToLoaderSection) +
-                       " and size 0x" + Twine::utohexstr(SizeOfLoaderSection) +
-                       " goes past the end of the file");
-
-  return LoderSectionStart;
-}
-
 Expected<uintptr_t> XCOFFObjectFile::getSectionFileOffsetToRawData(
     XCOFF::SectionTypeFlags SectType) const {
   DataRefImpl DRI = getSectionByType(SectType);
 
   if (DRI.p == 0) // No section is not an error.
     return 0;
 
   uint64_t SectionOffset = getSectionFileOffsetToRawData(DRI);
if (StringTablePtr[Size - 1] != '\0')
     return errorCodeToError(object_error::string_table_non_null_end);
 
   return XCOFFStringTable{Size, StringTablePtr};
 }
 
 // This function returns the import file table. Each entry in the import file
 // table consists of: "path_name\0base_name\0archive_member_name\0".
 Expected<StringRef> XCOFFObjectFile::getImportFileTable() const {
-  Expected<uintptr_t> LoaderSectionAddrOrError = getLoaderSectionAddress();
+  Expected<uintptr_t> LoaderSectionAddrOrError =
+      getSectionFileOffsetToRawData(XCOFF::STYP_LOADER);
   if (!LoaderSectionAddrOrError)
     return LoaderSectionAddrOrError.takeError();
 
   uintptr_t LoaderSectionAddr = LoaderSectionAddrOrError.get();
   if (!LoaderSectionAddr)
     return StringRef();
 
   uint64_t OffsetToImportFileTable = 0;