[llvm-readobj] - Simplify findSectionByName(). NFCI.

[grimar]

Summary

It turns out that findSectionByName can return
const Elf_Shdr * instead of Expected<>, because its
code never returns an error currently (it reports warnings instead).

[MaskRay]

LGTM.

[jhenderson]

Errrmmm... yeah, not sure how we missed that before! LGTM.

llvm/tools/llvm-readobj/ELFDumper.cpp

public:
   std::string getStaticSymbolName(uint32_t Index) const;
   StringRef getDynamicString(uint64_t Value) const;
   Expected<StringRef> getSymbolVersionByIndex(uint32_t VersionSymbolIndex,
                                               bool &IsDefault) const;
 
   void printSymbolsHelper(bool IsDynamic) const;
   std::string getDynamicEntry(uint64_t Type, uint64_t Value) const;
 
-  Expected<const typename ELFT::Shdr *> findSectionByName(StringRef Name) const;
+  const Elf_Shdr *findSectionByName(StringRef Name) const;
 
   const Elf_Shdr *getDotSymtabSec() const { return DotSymtabSec; }
   const Elf_Shdr *getDotCGProfileSec() const { return DotCGProfileSec; }
   const Elf_Shdr *getDotAddrsigSec() const { return DotAddrsigSec; }
   ArrayRef<Elf_Word> getShndxTable() const { return ShndxTable; }
   StringRef getDynamicStringTable() const { return DynamicStringTable; }
   const DynRegionInfo &getDynRelRegion() const { return DynRelRegion; }
   const DynRegionInfo &getDynRelaRegion() const { return DynRelaRegion; }
void printFlags(T Value, ArrayRef<EnumEntry<TFlag>> Flags, raw_ostream &OS) {
   }
 
   for (const auto &Flag : SetFlags) {
     OS << Flag.Name << " ";
   }
 }
 
 template <class ELFT>
-Expected<const typename ELFT::Shdr *>
+const typename ELFT::Shdr *
 ELFDumper<ELFT>::findSectionByName(StringRef Name) const {
   const ELFFile<ELFT> *Obj = ObjF->getELFFile();
   for (const Elf_Shdr &Shdr : cantFail(Obj->sections())) {
     if (Expected<StringRef> NameOrErr = Obj->getSectionName(&Shdr)) {
       if (*NameOrErr == Name)
         return &Shdr;
     } else {
       reportUniqueWarning(createError("unable to read the name of " +

 Error MipsGOTParser<ELFT>::findGOT(Elf_Dyn_Range DynTable,
                                    Elf_Sym_Range DynSyms) {
   // See "Global Offset Table" in Chapter 5 in the following document
   // for detailed GOT description.
   // ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
 
   // Find static GOT secton.
   if (IsStatic) {
-    Expected<const Elf_Shdr *> GotOrErr = Dumper.findSectionByName(".got");
-    if (!GotOrErr)
-      return GotOrErr.takeError();
-    else
-      GotSec = *GotOrErr;
-
+    GotSec = Dumper.findSectionByName(".got");
     if (!GotSec)
       return Error::success();
 
     ArrayRef<uint8_t> Content =
         unwrapOrError(FileName, Obj->getSectionContents(GotSec));
     GotEntries = Entries(reinterpret_cast<const Entry *>(Content.data()),
                          Content.size() / sizeof(Entry));
     LocalNum = GotEntries.size();
static void printMipsReginfoData(ScopedPrinter &W,
   W.printHex("Co-Proc Mask0", Reginfo.ri_cprmask[0]);
   W.printHex("Co-Proc Mask1", Reginfo.ri_cprmask[1]);
   W.printHex("Co-Proc Mask2", Reginfo.ri_cprmask[2]);
   W.printHex("Co-Proc Mask3", Reginfo.ri_cprmask[3]);
 }
 
 template <class ELFT> void ELFDumper<ELFT>::printMipsReginfo() {
   const ELFFile<ELFT> *Obj = ObjF->getELFFile();
-  Expected<const Elf_Shdr *> RegInfoOrErr = findSectionByName(".reginfo");
-  if (!RegInfoOrErr) {
-    reportUniqueWarning(RegInfoOrErr.takeError());
-    return;
-  }
-
-  if ((*RegInfoOrErr) == nullptr) {
+  const Elf_Shdr *RegInfo = findSectionByName(".reginfo");
+  if (!RegInfo) {
     W.startLine() << "There is no .reginfo section in the file.\n";
     return;
   }
 
   ArrayRef<uint8_t> Sec = unwrapOrError(ObjF->getFileName(),
-                                        Obj->getSectionContents(*RegInfoOrErr));
+                                        Obj->getSectionContents(RegInfo));
   if (Sec.size() != sizeof(Elf_Mips_RegInfo<ELFT>)) {
     W.startLine() << "The .reginfo section has a wrong size.\n";
     return;
   }
 
   DictScope GS(W, "MIPS RegInfo");
   auto *Reginfo = reinterpret_cast<const Elf_Mips_RegInfo<ELFT> *>(Sec.data());
   printMipsReginfoData(W, *Reginfo);
 }
 
 template <class ELFT> void ELFDumper<ELFT>::printMipsOptions() {
   const ELFFile<ELFT> *Obj = ObjF->getELFFile();
-  Expected<const Elf_Shdr *> MipsOptOrErr = findSectionByName(".MIPS.options");
-  if (!MipsOptOrErr) {
-    reportUniqueWarning(MipsOptOrErr.takeError());
-    return;
-  }
-
-  if ((*MipsOptOrErr) == nullptr) {
+  const Elf_Shdr *MipsOpts = findSectionByName(".MIPS.options");
+  if (!MipsOpts) {
     W.startLine() << "There is no .MIPS.options section in the file.\n";
     return;
   }
 
   DictScope GS(W, "MIPS Options");
 
-  ArrayRef<uint8_t> Sec = unwrapOrError(ObjF->getFileName(),
-                                        Obj->getSectionContents(*MipsOptOrErr));
+  ArrayRef<uint8_t> Sec =
+      unwrapOrError(ObjF->getFileName(), Obj->getSectionContents(MipsOpts));
   while (!Sec.empty()) {
     if (Sec.size() < sizeof(Elf_Mips_Options<ELFT>)) {
       W.startLine() << "The .MIPS.options section has a wrong size.\n";
       return;
     }
     auto *O = reinterpret_cast<const Elf_Mips_Options<ELFT> *>(Sec.data());
     DictScope GS(W, getElfMipsOptionsOdkType(O->kind));
     switch (O->kind) {
if (!Parser.getPltEntries().empty()) {
     }
   }
 }
 
 template <class ELFT>
 Expected<const Elf_Mips_ABIFlags<ELFT> *>
 getMipsAbiFlagsSection(const ELFObjectFile<ELFT> *ObjF,
                        const ELFDumper<ELFT> &Dumper) {
-  Expected<const typename ELFT::Shdr *> SecOrErr =
-      Dumper.findSectionByName(".MIPS.abiflags");
-  if (!SecOrErr)
-    return SecOrErr.takeError();
-  if (*SecOrErr == nullptr)
+  const typename ELFT::Shdr *Sec = Dumper.findSectionByName(".MIPS.abiflags");
+  if (Sec == nullptr)
     return nullptr;
 
   const ELFFile<ELFT> *Obj = ObjF->getELFFile();
   constexpr StringRef ErrPrefix = "unable to read the .MIPS.abiflags section: ";
-  Expected<ArrayRef<uint8_t>> DataOrErr = Obj->getSectionContents(*SecOrErr);
+  Expected<ArrayRef<uint8_t>> DataOrErr = Obj->getSectionContents(Sec);
   if (!DataOrErr)
     return createError(ErrPrefix + toString(DataOrErr.takeError()));
 
   if (DataOrErr->size() != sizeof(Elf_Mips_ABIFlags<ELFT>))
     return createError(ErrPrefix + "it has a wrong size (" +
         Twine(DataOrErr->size()) + ")");
   return reinterpret_cast<const Elf_Mips_ABIFlags<ELFT> *>(DataOrErr->data());
 }