[ELF] Convert ELF.h to Expected<T>.

This has two advantages:
1) We slowly move away from ErrorOr to the new handling interface,
in the hope of having an uniform error handling in LLVM, eventually.
2) We're starting to have *meaningful* error messages for invalid
object ELF files, rather than a generic "parse error". At some point
we should include also the offset to improve the quality of the
diagnostic.

llvm-svn: 287081

4 files changed, 102 insertions, 100 deletions

diff --git a/llvm/tools/llvm-objdump/ELFDump.cpp b/llvm/tools/llvm-objdump/ELFDump.cpp
index e9e0bcf30e8..2d2a5b581d1 100644
--- a/llvm/tools/llvm-objdump/ELFDump.cpp
+++ b/llvm/tools/llvm-objdump/ELFDump.cpp
@@ -25,8 +25,9 @@ template <class ELFT> void printProgramHeaders(const ELFFile<ELFT> *o) {
   typedef ELFFile<ELFT> ELFO;
   outs() << "Program Header:\n";
   auto ProgramHeaderOrError = o->program_headers();
-  if (std::error_code EC = ProgramHeaderOrError.getError())
-    report_fatal_error(EC.message());
+  if (!ProgramHeaderOrError)
+    report_fatal_error(
+        errorToErrorCode(ProgramHeaderOrError.takeError()).message());
   for (const typename ELFO::Elf_Phdr &Phdr : *ProgramHeaderOrError) {
     switch (Phdr.p_type) {
     case ELF::PT_LOAD:
diff --git a/llvm/tools/llvm-objdump/llvm-objdump.cpp b/llvm/tools/llvm-objdump/llvm-objdump.cpp
index 920ad4a7dd6..be44c7450d6 100644
--- a/llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ b/llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -608,22 +608,22 @@ static std::error_code getRelocationValueString(const ELFObjectFile<ELFT> *Obj,
 
   const ELFFile<ELFT> &EF = *Obj->getELFFile();
 
-  ErrorOr<const Elf_Shdr *> SecOrErr = EF.getSection(Rel.d.a);
-  if (std::error_code EC = SecOrErr.getError())
-    return EC;
+  auto SecOrErr = EF.getSection(Rel.d.a);
+  if (!SecOrErr)
+    return errorToErrorCode(SecOrErr.takeError());
   const Elf_Shdr *Sec = *SecOrErr;
-  ErrorOr<const Elf_Shdr *> SymTabOrErr = EF.getSection(Sec->sh_link);
-  if (std::error_code EC = SymTabOrErr.getError())
-    return EC;
+  auto SymTabOrErr = EF.getSection(Sec->sh_link);
+  if (!SymTabOrErr)
+    return errorToErrorCode(SymTabOrErr.takeError());
   const Elf_Shdr *SymTab = *SymTabOrErr;
   assert(SymTab->sh_type == ELF::SHT_SYMTAB ||
          SymTab->sh_type == ELF::SHT_DYNSYM);
-  ErrorOr<const Elf_Shdr *> StrTabSec = EF.getSection(SymTab->sh_link);
-  if (std::error_code EC = StrTabSec.getError())
-    return EC;
-  ErrorOr<StringRef> StrTabOrErr = EF.getStringTable(*StrTabSec);
-  if (std::error_code EC = StrTabOrErr.getError())
-    return EC;
+  auto StrTabSec = EF.getSection(SymTab->sh_link);
+  if (!StrTabSec)
+    return errorToErrorCode(StrTabSec.takeError());
+  auto StrTabOrErr = EF.getStringTable(*StrTabSec);
+  if (!StrTabOrErr)
+    return errorToErrorCode(StrTabOrErr.takeError());
   StringRef StrTab = *StrTabOrErr;
   uint8_t type = RelRef.getType();
   StringRef res;
@@ -649,9 +649,9 @@ static std::error_code getRelocationValueString(const ELFObjectFile<ELFT> *Obj,
     if (!SymSI)
       return errorToErrorCode(SymSI.takeError());
     const Elf_Shdr *SymSec = Obj->getSection((*SymSI)->getRawDataRefImpl());
-    ErrorOr<StringRef> SecName = EF.getSectionName(SymSec);
-    if (std::error_code EC = SecName.getError())
-      return EC;
+    auto SecName = EF.getSectionName(SymSec);
+    if (!SecName)
+      return errorToErrorCode(SecName.takeError());
     Target = *SecName;
   } else {
     Expected<StringRef> SymName = symb->getName(StrTab);
diff --git a/llvm/tools/llvm-readobj/ARMEHABIPrinter.h b/llvm/tools/llvm-readobj/ARMEHABIPrinter.h
index 78060e3abcd..903a246ccfd 100644
--- a/llvm/tools/llvm-readobj/ARMEHABIPrinter.h
+++ b/llvm/tools/llvm-readobj/ARMEHABIPrinter.h
@@ -349,8 +349,9 @@ template <typename ET>
 ErrorOr<StringRef>
 PrinterContext<ET>::FunctionAtAddress(unsigned Section,
                                       uint64_t Address) const {
-  ErrorOr<StringRef> StrTableOrErr = ELF->getStringTableForSymtab(*Symtab);
-  error(StrTableOrErr.getError());
+  auto StrTableOrErr = ELF->getStringTableForSymtab(*Symtab);
+  if (!StrTableOrErr)
+    error(StrTableOrErr.takeError());
   StringRef StrTable = *StrTableOrErr;
 
   for (const Elf_Sym &Sym : unwrapOrError(ELF->symbols(Symtab)))
@@ -383,8 +384,9 @@ PrinterContext<ET>::FindExceptionTable(unsigned IndexSectionIndex,
     if (Sec.sh_type != ELF::SHT_REL || Sec.sh_info != IndexSectionIndex)
       continue;
 
-    ErrorOr<const Elf_Shdr *> SymTabOrErr = ELF->getSection(Sec.sh_link);
-    error(SymTabOrErr.getError());
+    auto SymTabOrErr = ELF->getSection(Sec.sh_link);
+    if (!SymTabOrErr)
+      error(SymTabOrErr.takeError());
     const Elf_Shdr *SymTab = *SymTabOrErr;
 
     for (const Elf_Rel &R : unwrapOrError(ELF->rels(&Sec))) {
@@ -399,10 +401,9 @@ PrinterContext<ET>::FindExceptionTable(unsigned IndexSectionIndex,
       const Elf_Sym *Symbol =
           unwrapOrError(ELF->getRelocationSymbol(&RelA, SymTab));
 
-      ErrorOr<const Elf_Shdr *> Ret =
-          ELF->getSection(Symbol, SymTab, ShndxTable);
-      if (std::error_code EC = Ret.getError())
-        report_fatal_error(EC.message());
+      auto Ret = ELF->getSection(Symbol, SymTab, ShndxTable);
+      if (!Ret)
+        report_fatal_error(errorToErrorCode(Ret.takeError()).message());
       return *Ret;
     }
   }
@@ -413,7 +414,7 @@ template <typename ET>
 void PrinterContext<ET>::PrintExceptionTable(const Elf_Shdr *IT,
                                              const Elf_Shdr *EHT,
                                              uint64_t TableEntryOffset) const {
-  ErrorOr<ArrayRef<uint8_t> > Contents = ELF->getSectionContents(EHT);
+  Expected<ArrayRef<uint8_t>> Contents = ELF->getSectionContents(EHT);
   if (!Contents)
     return;
 
@@ -480,7 +481,7 @@ void PrinterContext<ET>::PrintOpcodes(const uint8_t *Entry,
 template <typename ET>
 void PrinterContext<ET>::PrintIndexTable(unsigned SectionIndex,
                                          const Elf_Shdr *IT) const {
-  ErrorOr<ArrayRef<uint8_t> > Contents = ELF->getSectionContents(IT);
+  Expected<ArrayRef<uint8_t>> Contents = ELF->getSectionContents(IT);
   if (!Contents)
     return;
 
@@ -533,7 +534,7 @@ void PrinterContext<ET>::PrintIndexTable(unsigned SectionIndex,
       const Elf_Shdr *EHT =
         FindExceptionTable(SectionIndex, Entry * IndexTableEntrySize + 4);
 
-      if (ErrorOr<StringRef> Name = ELF->getSectionName(EHT))
+      if (auto Name = ELF->getSectionName(EHT))
         SW.printString("ExceptionHandlingTable", *Name);
 
       uint64_t TableEntryOffset = PREL31(Word1, IT->sh_addr);
@@ -554,7 +555,7 @@ void PrinterContext<ET>::PrintUnwindInformation() const {
       DictScope UIT(SW, "UnwindIndexTable");
 
       SW.printNumber("SectionIndex", SectionIndex);
-      if (ErrorOr<StringRef> SectionName = ELF->getSectionName(&Sec))
+      if (auto SectionName = ELF->getSectionName(&Sec))
         SW.printString("SectionName", *SectionName);
       SW.printHex("SectionOffset", Sec.sh_offset);
 
diff --git a/llvm/tools/obj2yaml/elf2yaml.cpp b/llvm/tools/obj2yaml/elf2yaml.cpp
index ffcb2d0ece4..697ab79d3b5 100644
--- a/llvm/tools/obj2yaml/elf2yaml.cpp
+++ b/llvm/tools/obj2yaml/elf2yaml.cpp
@@ -75,8 +75,8 @@ ErrorOr<ELFYAML::Object *> ELFDumper<ELFT>::dump() {
 
   // Dump sections
   auto SectionsOrErr = Obj.sections();
-  if (std::error_code EC = SectionsOrErr.getError())
-    return EC;
+  if (!SectionsOrErr)
+    return errorToErrorCode(SectionsOrErr.takeError());
   for (const Elf_Shdr &Sec : *SectionsOrErr) {
     switch (Sec.sh_type) {
     case ELF::SHT_NULL:
@@ -88,9 +88,9 @@ ErrorOr<ELFYAML::Object *> ELFDumper<ELFT>::dump() {
       Symtab = &Sec;
       break;
     case ELF::SHT_SYMTAB_SHNDX: {
-      ErrorOr<ArrayRef<Elf_Word>> TableOrErr = Obj.getSHNDXTable(Sec);
-      if (std::error_code EC = TableOrErr.getError())
-        return EC;
+      auto TableOrErr = Obj.getSHNDXTable(Sec);
+      if (!TableOrErr)
+        return errorToErrorCode(TableOrErr.takeError());
       ShndxTable = *TableOrErr;
       break;
     }
@@ -139,15 +139,15 @@ ErrorOr<ELFYAML::Object *> ELFDumper<ELFT>::dump() {
   }
 
   // Dump symbols
-  ErrorOr<StringRef> StrTableOrErr = Obj.getStringTableForSymtab(*Symtab);
-  if (std::error_code EC = StrTableOrErr.getError())
-    return EC;
+  auto StrTableOrErr = Obj.getStringTableForSymtab(*Symtab);
+  if (!StrTableOrErr)
+    return errorToErrorCode(StrTableOrErr.takeError());
   StringRef StrTable = *StrTableOrErr;
 
   bool IsFirstSym = true;
   auto SymtabOrErr = Obj.symbols(Symtab);
-  if (std::error_code EC = SymtabOrErr.getError())
-    return EC;
+  if (!SymtabOrErr)
+    return errorToErrorCode(SymtabOrErr.takeError());
   for (const Elf_Sym &Sym : *SymtabOrErr) {
     if (IsFirstSym) {
       IsFirstSym = false;
@@ -192,16 +192,16 @@ ELFDumper<ELFT>::dumpSymbol(const Elf_Sym *Sym, const Elf_Shdr *SymTab,
     return errorToErrorCode(SymbolNameOrErr.takeError());
   S.Name = SymbolNameOrErr.get();
 
-  ErrorOr<const Elf_Shdr *> ShdrOrErr = Obj.getSection(Sym, SymTab, ShndxTable);
-  if (std::error_code EC = ShdrOrErr.getError())
-    return EC;
+  auto ShdrOrErr = Obj.getSection(Sym, SymTab, ShndxTable);
+  if (!ShdrOrErr)
+    return errorToErrorCode(ShdrOrErr.takeError());
   const Elf_Shdr *Shdr = *ShdrOrErr;
   if (!Shdr)
     return obj2yaml_error::success;
 
-  ErrorOr<StringRef> NameOrErr = Obj.getSectionName(Shdr);
-  if (std::error_code EC = NameOrErr.getError())
-    return EC;
+  auto NameOrErr = Obj.getSectionName(Shdr);
+  if (!NameOrErr)
+    return errorToErrorCode(NameOrErr.takeError());
   S.Section = NameOrErr.get();
 
   return obj2yaml_error::success;
@@ -217,15 +217,15 @@ std::error_code ELFDumper<ELFT>::dumpRelocation(const RelT *Rel,
   R.Addend = 0;
 
   auto SymOrErr = Obj.getRelocationSymbol(Rel, SymTab);
-  if (std::error_code EC = SymOrErr.getError())
-    return EC;
+  if (!SymOrErr)
+    return errorToErrorCode(SymOrErr.takeError());
   const Elf_Sym *Sym = *SymOrErr;
-  ErrorOr<const Elf_Shdr *> StrTabSec = Obj.getSection(SymTab->sh_link);
-  if (std::error_code EC = StrTabSec.getError())
-    return EC;
-  ErrorOr<StringRef> StrTabOrErr = Obj.getStringTable(*StrTabSec);
-  if (std::error_code EC = StrTabOrErr.getError())
-    return EC;
+  auto StrTabSec = Obj.getSection(SymTab->sh_link);
+  if (!StrTabSec)
+    return errorToErrorCode(StrTabSec.takeError());
+  auto StrTabOrErr = Obj.getStringTable(*StrTabSec);
+  if (!StrTabOrErr)
+    return errorToErrorCode(StrTabOrErr.takeError());
   StringRef StrTab = *StrTabOrErr;
 
   Expected<StringRef> NameOrErr = Sym->getName(StrTab);
@@ -244,18 +244,18 @@ std::error_code ELFDumper<ELFT>::dumpCommonSection(const Elf_Shdr *Shdr,
   S.Address = Shdr->sh_addr;
   S.AddressAlign = Shdr->sh_addralign;
 
-  ErrorOr<StringRef> NameOrErr = Obj.getSectionName(Shdr);
-  if (std::error_code EC = NameOrErr.getError())
-    return EC;
+  auto NameOrErr = Obj.getSectionName(Shdr);
+  if (!NameOrErr)
+    return errorToErrorCode(NameOrErr.takeError());
   S.Name = NameOrErr.get();
 
   if (Shdr->sh_link != ELF::SHN_UNDEF) {
-    ErrorOr<const Elf_Shdr *> LinkSection = Obj.getSection(Shdr->sh_link);
-    if (std::error_code EC = LinkSection.getError())
-      return EC;
+    auto LinkSection = Obj.getSection(Shdr->sh_link);
+    if (LinkSection.takeError())
+      return errorToErrorCode(LinkSection.takeError());
     NameOrErr = Obj.getSectionName(*LinkSection);
-    if (std::error_code EC = NameOrErr.getError())
-      return EC;
+    if (!NameOrErr)
+      return errorToErrorCode(NameOrErr.takeError());
     S.Link = NameOrErr.get();
   }
 
@@ -269,13 +269,13 @@ ELFDumper<ELFT>::dumpCommonRelocationSection(const Elf_Shdr *Shdr,
   if (std::error_code EC = dumpCommonSection(Shdr, S))
     return EC;
 
-  ErrorOr<const Elf_Shdr *> InfoSection = Obj.getSection(Shdr->sh_info);
-  if (std::error_code EC = InfoSection.getError())
-    return EC;
+  auto InfoSection = Obj.getSection(Shdr->sh_info);
+  if (!InfoSection)
+    return errorToErrorCode(InfoSection.takeError());
 
-  ErrorOr<StringRef> NameOrErr = Obj.getSectionName(*InfoSection);
-  if (std::error_code EC = NameOrErr.getError())
-    return EC;
+  auto NameOrErr = Obj.getSectionName(*InfoSection);
+  if (!NameOrErr)
+    return errorToErrorCode(NameOrErr.takeError());
   S.Info = NameOrErr.get();
 
   return obj2yaml_error::success;
@@ -290,14 +290,14 @@ ELFDumper<ELFT>::dumpRelSection(const Elf_Shdr *Shdr) {
   if (std::error_code EC = dumpCommonRelocationSection(Shdr, *S))
     return EC;
 
-  ErrorOr<const Elf_Shdr *> SymTabOrErr = Obj.getSection(Shdr->sh_link);
-  if (std::error_code EC = SymTabOrErr.getError())
-    return EC;
+  auto SymTabOrErr = Obj.getSection(Shdr->sh_link);
+  if (!SymTabOrErr)
+    return errorToErrorCode(SymTabOrErr.takeError());
   const Elf_Shdr *SymTab = *SymTabOrErr;
 
   auto Rels = Obj.rels(Shdr);
-  if (std::error_code EC = Rels.getError())
-    return EC;
+  if (!Rels)
+    return errorToErrorCode(Rels.takeError());
   for (const Elf_Rel &Rel : *Rels) {
     ELFYAML::Relocation R;
     if (std::error_code EC = dumpRelocation(&Rel, SymTab, R))
@@ -317,14 +317,14 @@ ELFDumper<ELFT>::dumpRelaSection(const Elf_Shdr *Shdr) {
   if (std::error_code EC = dumpCommonRelocationSection(Shdr, *S))
     return EC;
 
-  ErrorOr<const Elf_Shdr *> SymTabOrErr = Obj.getSection(Shdr->sh_link);
-  if (std::error_code EC = SymTabOrErr.getError())
-    return EC;
+  auto SymTabOrErr = Obj.getSection(Shdr->sh_link);
+  if (!SymTabOrErr)
+    return errorToErrorCode(SymTabOrErr.takeError());
   const Elf_Shdr *SymTab = *SymTabOrErr;
 
   auto Rels = Obj.relas(Shdr);
-  if (std::error_code EC = Rels.getError())
-    return EC;
+  if (!Rels)
+    return errorToErrorCode(Rels.takeError());
   for (const Elf_Rela &Rel : *Rels) {
     ELFYAML::Relocation R;
     if (std::error_code EC = dumpRelocation(&Rel, SymTab, R))
@@ -344,9 +344,9 @@ ELFDumper<ELFT>::dumpContentSection(const Elf_Shdr *Shdr) {
   if (std::error_code EC = dumpCommonSection(Shdr, *S))
     return EC;
 
-  ErrorOr<ArrayRef<uint8_t>> ContentOrErr = Obj.getSectionContents(Shdr);
-  if (std::error_code EC = ContentOrErr.getError())
-    return EC;
+  auto ContentOrErr = Obj.getSectionContents(Shdr);
+  if (!ContentOrErr)
+    return errorToErrorCode(ContentOrErr.takeError());
   S->Content = yaml::BinaryRef(ContentOrErr.get());
   S->Size = S->Content.binary_size();
 
@@ -372,21 +372,21 @@ ErrorOr<ELFYAML::Group *> ELFDumper<ELFT>::dumpGroup(const Elf_Shdr *Shdr) {
   if (std::error_code EC = dumpCommonSection(Shdr, *S))
     return EC;
   // Get sh_info which is the signature.
-  ErrorOr<const Elf_Shdr *> SymtabOrErr = Obj.getSection(Shdr->sh_link);
-  if (std::error_code EC = SymtabOrErr.getError())
-    return EC;
+  auto SymtabOrErr = Obj.getSection(Shdr->sh_link);
+  if (!SymtabOrErr)
+    return errorToErrorCode(SymtabOrErr.takeError());
   const Elf_Shdr *Symtab = *SymtabOrErr;
-  ErrorOr<const Elf_Sym *> SymOrErr = Obj.getSymbol(Symtab, Shdr->sh_info);
-  if (std::error_code EC = SymOrErr.getError())
-    return EC;
+  auto SymOrErr = Obj.getSymbol(Symtab, Shdr->sh_info);
+  if (!SymOrErr)
+    return errorToErrorCode(SymOrErr.takeError());
   const Elf_Sym *symbol = *SymOrErr;
-  ErrorOr<StringRef> StrTabOrErr = Obj.getStringTableForSymtab(*Symtab);
-  if (std::error_code EC = StrTabOrErr.getError())
-    return EC;
+  auto StrTabOrErr = Obj.getStringTableForSymtab(*Symtab);
+  if (!StrTabOrErr)
+    return errorToErrorCode(StrTabOrErr.takeError());
   StringRef StrTab = *StrTabOrErr;
   auto sectionContents = Obj.getSectionContents(Shdr);
-  if (std::error_code ec = sectionContents.getError())
-    return ec;
+  if (!sectionContents)
+    return errorToErrorCode(sectionContents.takeError());
   Expected<StringRef> symbolName = symbol->getName(StrTab);
   if (!symbolName)
     return errorToErrorCode(symbolName.takeError());
@@ -399,12 +399,12 @@ ErrorOr<ELFYAML::Group *> ELFDumper<ELFT>::dumpGroup(const Elf_Shdr *Shdr) {
     if (groupMembers[i] == llvm::ELF::GRP_COMDAT) {
       s.sectionNameOrType = "GRP_COMDAT";
     } else {
-      ErrorOr<const Elf_Shdr *> sHdr = Obj.getSection(groupMembers[i]);
-      if (std::error_code EC = sHdr.getError())
-        return EC;
-      ErrorOr<StringRef> sectionName = Obj.getSectionName(*sHdr);
-      if (std::error_code ec = sectionName.getError())
-        return ec;
+      auto sHdr = Obj.getSection(groupMembers[i]);
+      if (!sHdr)
+        return errorToErrorCode(sHdr.takeError());
+      auto sectionName = Obj.getSectionName(*sHdr);
+      if (!sectionName)
+        return errorToErrorCode(sectionName.takeError());
       s.sectionNameOrType = *sectionName;
     }
     S->Members.push_back(s);
@@ -421,9 +421,9 @@ ELFDumper<ELFT>::dumpMipsABIFlags(const Elf_Shdr *Shdr) {
   if (std::error_code EC = dumpCommonSection(Shdr, *S))
     return EC;
 
-  ErrorOr<ArrayRef<uint8_t>> ContentOrErr = Obj.getSectionContents(Shdr);
-  if (std::error_code EC = ContentOrErr.getError())
-    return EC;
+  auto ContentOrErr = Obj.getSectionContents(Shdr);
+  if (!ContentOrErr)
+    return errorToErrorCode(ContentOrErr.takeError());
 
   auto *Flags = reinterpret_cast<const object::Elf_Mips_ABIFlags<ELFT> *>(
       ContentOrErr.get().data());