Recommit r368812 "[llvm/Object] - Convert SectionRef::getName() to return Expected<>"

Changes: no changes. A fix for the clang code will be landed right on top.

Original commit message:

SectionRef::getName() returns std::error_code now.
Returning Expected<> instead has multiple benefits.

For example, it forces user to check the error returned.
Also Expected<> may keep a valuable string error message,
what is more useful than having a error code.
(Object\invalid.test was updated to show the new messages printed.)

This patch makes a change for all users to switch to Expected<> version.

Note: in a few places the error returned was ignored before my changes.
In such places I left them ignored. My intention was to convert the interface
used, and not to improve and/or the existent users in this patch.
(Though I think this is good idea for a follow-ups to revisit such places
and either remove consumeError calls or comment each of them to clarify why
it is OK to have them).

Differential revision: https://reviews.llvm.org/D66089

llvm-svn: 368826

3 files changed, 146 insertions, 70 deletions

diff --git a/llvm/tools/llvm-objdump/COFFDump.cpp b/llvm/tools/llvm-objdump/COFFDump.cpp
index 1ba0a68902c..3fb9285bf27 100644
--- a/llvm/tools/llvm-objdump/COFFDump.cpp
+++ b/llvm/tools/llvm-objdump/COFFDump.cpp
@@ -442,8 +442,7 @@ static bool getPDataSection(const COFFObjectFile *Obj,
                             std::vector<RelocationRef> &Rels,
                             const RuntimeFunction *&RFStart, int &NumRFs) {
   for (const SectionRef &Section : Obj->sections()) {
-    StringRef Name;
-    error(Section.getName(Name));
+    StringRef Name = unwrapOrError(Section.getName(), Obj->getFileName());
     if (Name != ".pdata")
       continue;
 
diff --git a/llvm/tools/llvm-objdump/MachODump.cpp b/llvm/tools/llvm-objdump/MachODump.cpp
index a3f3a9df4c1..c4fa6b5c2a2 100644
--- a/llvm/tools/llvm-objdump/MachODump.cpp
+++ b/llvm/tools/llvm-objdump/MachODump.cpp
@@ -371,11 +371,8 @@ static void getSectionsAndSymbols(MachOObjectFile *MachOObj,
       Symbols.push_back(Symbol);
   }
 
-  for (const SectionRef &Section : MachOObj->sections()) {
-    StringRef SectName;
-    Section.getName(SectName);
+  for (const SectionRef &Section : MachOObj->sections())
     Sections.push_back(Section);
-  }
 
   bool BaseSegmentAddressSet = false;
   for (const auto &Command : MachOObj->load_commands()) {
@@ -449,13 +446,11 @@ static void printRelocationTargetName(const MachOObjectFile *O,
     // If we couldn't find a symbol that this relocation refers to, try
     // to find a section beginning instead.
     for (const SectionRef &Section : ToolSectionFilter(*O)) {
-      StringRef Name;
       uint64_t Addr = Section.getAddress();
       if (Addr != Val)
         continue;
-      if (std::error_code EC = Section.getName(Name))
-        report_error(errorCodeToError(EC), O->getFileName());
-      Fmt << Name;
+      StringRef NameOrErr = unwrapOrError(Section.getName(), O->getFileName());
+      Fmt << NameOrErr;
       return;
     }
 
@@ -488,10 +483,14 @@ static void printRelocationTargetName(const MachOObjectFile *O,
       --I;
       advance(SI, 1);
     }
-    if (SI == O->section_end())
+    if (SI == O->section_end()) {
       Fmt << Val << " (?,?)";
-    else
-      SI->getName(S);
+    } else {
+      if (Expected<StringRef> NameOrErr = SI->getName())
+        S = *NameOrErr;
+      else
+        consumeError(NameOrErr.takeError());
+    }
   }
 
   Fmt << S;
@@ -1531,7 +1530,12 @@ static void DumpLiteralPointerSection(MachOObjectFile *O,
     uint64_t SectSize = Sect->getSize();
 
     StringRef SectName;
-    Sect->getName(SectName);
+    Expected<StringRef> SectNameOrErr = Sect->getName();
+    if (SectNameOrErr)
+      SectName = *SectNameOrErr;
+    else
+      consumeError(SectNameOrErr.takeError());
+
     DataRefImpl Ref = Sect->getRawDataRefImpl();
     StringRef SegmentName = O->getSectionFinalSegmentName(Ref);
     outs() << SegmentName << ":" << SectName << ":";
@@ -1743,7 +1747,12 @@ static void DumpSectionContents(StringRef Filename, MachOObjectFile *O,
     }
     for (const SectionRef &Section : O->sections()) {
       StringRef SectName;
-      Section.getName(SectName);
+      Expected<StringRef> SecNameOrErr = Section.getName();
+      if (SecNameOrErr)
+        SectName = *SecNameOrErr;
+      else
+        consumeError(SecNameOrErr.takeError());
+
       DataRefImpl Ref = Section.getRawDataRefImpl();
       StringRef SegName = O->getSectionFinalSegmentName(Ref);
       if ((DumpSegName.empty() || SegName == DumpSegName) &&
@@ -1839,7 +1848,12 @@ static void DumpInfoPlistSectionContents(StringRef Filename,
                                          MachOObjectFile *O) {
   for (const SectionRef &Section : O->sections()) {
     StringRef SectName;
-    Section.getName(SectName);
+    Expected<StringRef> SecNameOrErr = Section.getName();
+    if (SecNameOrErr)
+      SectName = *SecNameOrErr;
+    else
+      consumeError(SecNameOrErr.takeError());
+
     DataRefImpl Ref = Section.getRawDataRefImpl();
     StringRef SegName = O->getSectionFinalSegmentName(Ref);
     if (SegName == "__TEXT" && SectName == "__info_plist") {
@@ -1936,7 +1950,11 @@ static void ProcessMachO(StringRef Name, MachOObjectFile *MachOOF,
   if (DisassembleAll) {
     for (const SectionRef &Section : MachOOF->sections()) {
       StringRef SectName;
-      Section.getName(SectName);
+      if (Expected<StringRef> NameOrErr = Section.getName())
+        SectName = *NameOrErr;
+      else
+        consumeError(NameOrErr.takeError());
+
       if (SectName.equals("__text")) {
         DataRefImpl Ref = Section.getRawDataRefImpl();
         StringRef SegName = MachOOF->getSectionFinalSegmentName(Ref);
@@ -3247,7 +3265,13 @@ static const char *get_pointer_64(uint64_t Address, uint32_t &offset,
       continue;
     if (objc_only) {
       StringRef SectName;
-      ((*(info->Sections))[SectIdx]).getName(SectName);
+      Expected<StringRef> SecNameOrErr =
+          ((*(info->Sections))[SectIdx]).getName();
+      if (SecNameOrErr)
+        SectName = *SecNameOrErr;
+      else
+        consumeError(SecNameOrErr.takeError());
+
       DataRefImpl Ref = ((*(info->Sections))[SectIdx]).getRawDataRefImpl();
       StringRef SegName = info->O->getSectionFinalSegmentName(Ref);
       if (SegName != "__OBJC" && SectName != "__cstring")
@@ -4039,7 +4063,12 @@ static const SectionRef get_section(MachOObjectFile *O, const char *segname,
                                     const char *sectname) {
   for (const SectionRef &Section : O->sections()) {
     StringRef SectName;
-    Section.getName(SectName);
+    Expected<StringRef> SecNameOrErr = Section.getName();
+    if (SecNameOrErr)
+      SectName = *SecNameOrErr;
+    else
+      consumeError(SecNameOrErr.takeError());
+
     DataRefImpl Ref = Section.getRawDataRefImpl();
     StringRef SegName = O->getSectionFinalSegmentName(Ref);
     if (SegName == segname && SectName == sectname)
@@ -4056,7 +4085,12 @@ walk_pointer_list_64(const char *listname, const SectionRef S,
     return;
 
   StringRef SectName;
-  S.getName(SectName);
+  Expected<StringRef> SecNameOrErr = S.getName();
+  if (SecNameOrErr)
+    SectName = *SecNameOrErr;
+  else
+    consumeError(SecNameOrErr.takeError());
+
   DataRefImpl Ref = S.getRawDataRefImpl();
   StringRef SegName = O->getSectionFinalSegmentName(Ref);
   outs() << "Contents of (" << SegName << "," << SectName << ") section\n";
@@ -4105,8 +4139,7 @@ walk_pointer_list_32(const char *listname, const SectionRef S,
   if (S == SectionRef())
     return;
 
-  StringRef SectName;
-  S.getName(SectName);
+  StringRef SectName = unwrapOrError(S.getName(), O->getFileName());
   DataRefImpl Ref = S.getRawDataRefImpl();
   StringRef SegName = O->getSectionFinalSegmentName(Ref);
   outs() << "Contents of (" << SegName << "," << SectName << ") section\n";
@@ -5780,7 +5813,12 @@ static void print_message_refs64(SectionRef S, struct DisassembleInfo *info) {
     return;
 
   StringRef SectName;
-  S.getName(SectName);
+  Expected<StringRef> SecNameOrErr = S.getName();
+  if (SecNameOrErr)
+    SectName = *SecNameOrErr;
+  else
+    consumeError(SecNameOrErr.takeError());
+
   DataRefImpl Ref = S.getRawDataRefImpl();
   StringRef SegName = info->O->getSectionFinalSegmentName(Ref);
   outs() << "Contents of (" << SegName << "," << SectName << ") section\n";
@@ -5843,7 +5881,12 @@ static void print_message_refs32(SectionRef S, struct DisassembleInfo *info) {
     return;
 
   StringRef SectName;
-  S.getName(SectName);
+  Expected<StringRef> SecNameOrErr = S.getName();
+  if (SecNameOrErr)
+    SectName = *SecNameOrErr;
+  else
+    consumeError(SecNameOrErr.takeError());
+
   DataRefImpl Ref = S.getRawDataRefImpl();
   StringRef SegName = info->O->getSectionFinalSegmentName(Ref);
   outs() << "Contents of (" << SegName << "," << SectName << ") section\n";
@@ -5889,7 +5932,12 @@ static void print_image_info64(SectionRef S, struct DisassembleInfo *info) {
     return;
 
   StringRef SectName;
-  S.getName(SectName);
+  Expected<StringRef> SecNameOrErr = S.getName();
+  if (SecNameOrErr)
+    SectName = *SecNameOrErr;
+  else
+    consumeError(SecNameOrErr.takeError());
+
   DataRefImpl Ref = S.getRawDataRefImpl();
   StringRef SegName = info->O->getSectionFinalSegmentName(Ref);
   outs() << "Contents of (" << SegName << "," << SectName << ") section\n";
@@ -5946,7 +5994,12 @@ static void print_image_info32(SectionRef S, struct DisassembleInfo *info) {
     return;
 
   StringRef SectName;
-  S.getName(SectName);
+  Expected<StringRef> SecNameOrErr = S.getName();
+  if (SecNameOrErr)
+    SectName = *SecNameOrErr;
+  else
+    consumeError(SecNameOrErr.takeError());
+
   DataRefImpl Ref = S.getRawDataRefImpl();
   StringRef SegName = info->O->getSectionFinalSegmentName(Ref);
   outs() << "Contents of (" << SegName << "," << SectName << ") section\n";
@@ -5996,7 +6049,12 @@ static void print_image_info(SectionRef S, struct DisassembleInfo *info) {
   const char *r;
 
   StringRef SectName;
-  S.getName(SectName);
+  Expected<StringRef> SecNameOrErr = S.getName();
+  if (SecNameOrErr)
+    SectName = *SecNameOrErr;
+  else
+    consumeError(SecNameOrErr.takeError());
+
   DataRefImpl Ref = S.getRawDataRefImpl();
   StringRef SegName = info->O->getSectionFinalSegmentName(Ref);
   outs() << "Contents of (" << SegName << "," << SectName << ") section\n";
@@ -6031,11 +6089,8 @@ static void printObjc2_64bit_MetaData(MachOObjectFile *O, bool verbose) {
     CreateSymbolAddressMap(O, &AddrMap);
 
   std::vector<SectionRef> Sections;
-  for (const SectionRef &Section : O->sections()) {
-    StringRef SectName;
-    Section.getName(SectName);
+  for (const SectionRef &Section : O->sections())
     Sections.push_back(Section);
-  }
 
   struct DisassembleInfo info(O, &AddrMap, &Sections, verbose);
 
@@ -6116,11 +6171,8 @@ static void printObjc2_32bit_MetaData(MachOObjectFile *O, bool verbose) {
     CreateSymbolAddressMap(O, &AddrMap);
 
   std::vector<SectionRef> Sections;
-  for (const SectionRef &Section : O->sections()) {
-    StringRef SectName;
-    Section.getName(SectName);
+  for (const SectionRef &Section : O->sections())
     Sections.push_back(Section);
-  }
 
   struct DisassembleInfo info(O, &AddrMap, &Sections, verbose);
 
@@ -6214,11 +6266,8 @@ static bool printObjc1_32bit_MetaData(MachOObjectFile *O, bool verbose) {
     CreateSymbolAddressMap(O, &AddrMap);
 
   std::vector<SectionRef> Sections;
-  for (const SectionRef &Section : O->sections()) {
-    StringRef SectName;
-    Section.getName(SectName);
+  for (const SectionRef &Section : O->sections())
     Sections.push_back(Section);
-  }
 
   struct DisassembleInfo info(O, &AddrMap, &Sections, verbose);
 
@@ -6375,11 +6424,8 @@ static void DumpProtocolSection(MachOObjectFile *O, const char *sect,
   CreateSymbolAddressMap(O, &AddrMap);
 
   std::vector<SectionRef> Sections;
-  for (const SectionRef &Section : O->sections()) {
-    StringRef SectName;
-    Section.getName(SectName);
+  for (const SectionRef &Section : O->sections())
     Sections.push_back(Section);
-  }
 
   struct DisassembleInfo info(O, &AddrMap, &Sections, true);
 
@@ -7344,8 +7390,12 @@ static void DisassembleMachO(StringRef Filename, MachOObjectFile *MachOOF,
     outs() << "(" << DisSegName << "," << DisSectName << ") section\n";
 
   for (unsigned SectIdx = 0; SectIdx != Sections.size(); SectIdx++) {
-    StringRef SectName;
-    if (Sections[SectIdx].getName(SectName) || SectName != DisSectName)
+    Expected<StringRef> SecNameOrErr = Sections[SectIdx].getName();
+    if (!SecNameOrErr) {
+      consumeError(SecNameOrErr.takeError());
+      continue;
+    }
+    if (*SecNameOrErr != DisSectName)
       continue;
 
     DataRefImpl DR = Sections[SectIdx].getRawDataRefImpl();
@@ -7742,8 +7792,12 @@ static void findUnwindRelocNameAddend(const MachOObjectFile *Obj,
   auto Sym = Symbols.upper_bound(Addr);
   if (Sym == Symbols.begin()) {
     // The first symbol in the object is after this reference, the best we can
-    // do is section-relative notation.
-    RelocSection.getName(Name);
+    // do is section-relative notation.  
+    if (Expected<StringRef> NameOrErr = RelocSection.getName())
+      Name = *NameOrErr;
+    else
+      consumeError(NameOrErr.takeError());
+
     Addend = Addr - SectionAddr;
     return;
   }
@@ -7762,7 +7816,11 @@ static void findUnwindRelocNameAddend(const MachOObjectFile *Obj,
 
   // There is a symbol before this reference, but it's in a different
   // section. Probably not helpful to mention it, so use the section name.
-  RelocSection.getName(Name);
+  if (Expected<StringRef> NameOrErr = RelocSection.getName())
+    Name = *NameOrErr;
+  else
+    consumeError(NameOrErr.takeError());
+
   Addend = Addr - SectionAddr;
 }
 
@@ -8127,7 +8185,11 @@ void printMachOUnwindInfo(const MachOObjectFile *Obj) {
 
   for (const SectionRef &Section : Obj->sections()) {
     StringRef SectName;
-    Section.getName(SectName);
+    if (Expected<StringRef> NameOrErr = Section.getName())
+      SectName = *NameOrErr;
+    else
+      consumeError(NameOrErr.takeError());
+
     if (SectName == "__compact_unwind")
       printMachOCompactUnwindSection(Obj, Symbols, Section);
     else if (SectName == "__unwind_info")
diff --git a/llvm/tools/llvm-objdump/llvm-objdump.cpp b/llvm/tools/llvm-objdump/llvm-objdump.cpp
index 93833858282..7a04e1195ed 100644
--- a/llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ b/llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -344,10 +344,14 @@ typedef std::vector<std::tuple<uint64_t, StringRef, uint8_t>> SectionSymbolsTy;
 static bool shouldKeep(object::SectionRef S) {
   if (FilterSections.empty())
     return true;
-  StringRef SecName;
-  std::error_code error = S.getName(SecName);
-  if (error)
+
+  Expected<StringRef> SecNameOrErr = S.getName();
+  if (!SecNameOrErr) {
+    consumeError(SecNameOrErr.takeError());
     return false;
+  }
+  StringRef SecName = *SecNameOrErr;
+
   // StringSet does not allow empty key so avoid adding sections with
   // no name (such as the section with index 0) here.
   if (!SecName.empty())
@@ -920,10 +924,12 @@ static void addPltEntries(const ObjectFile *Obj,
                           StringSaver &Saver) {
   Optional<SectionRef> Plt = None;
   for (const SectionRef &Section : Obj->sections()) {
-    StringRef Name;
-    if (Section.getName(Name))
+    Expected<StringRef> SecNameOrErr = Section.getName();
+    if (!SecNameOrErr) {
+      consumeError(SecNameOrErr.takeError());
       continue;
-    if (Name == ".plt")
+    }
+    if (*SecNameOrErr == ".plt")
       Plt = Section;
   }
   if (!Plt)
@@ -1206,9 +1212,8 @@ static void disassembleObject(const Target *TheTarget, const ObjectFile *Obj,
       DataRefImpl DR = Section.getRawDataRefImpl();
       SegmentName = MachO->getSectionFinalSegmentName(DR);
     }
-    StringRef SectionName;
-    error(Section.getName(SectionName));
 
+    StringRef SectionName = unwrapOrError(Section.getName(), Obj->getFileName());
     // If the section has no symbol at the start, just insert a dummy one.
     if (Symbols.empty() || std::get<0>(Symbols[0]) != 0) {
       Symbols.insert(
@@ -1581,8 +1586,7 @@ void printRelocations(const ObjectFile *Obj) {
   }
 
   for (std::pair<SectionRef, std::vector<SectionRef>> &P : SecToRelSec) {
-    StringRef SecName;
-    error(P.first.getName(SecName));
+    StringRef SecName = unwrapOrError(P.first.getName(), Obj->getFileName());
     outs() << "RELOCATION RECORDS FOR [" << SecName << "]:\n";
 
     for (SectionRef Section : P.second) {
@@ -1654,8 +1658,7 @@ void printSectionHeaders(const ObjectFile *Obj) {
               "Idx Name          Size     VMA          Type\n";
 
   for (const SectionRef &Section : ToolSectionFilter(*Obj)) {
-    StringRef Name;
-    error(Section.getName(Name));
+    StringRef Name = unwrapOrError(Section.getName(), Obj->getFileName());
     uint64_t VMA = Section.getAddress();
     if (shouldAdjustVA(Section))
       VMA += AdjustVMA;
@@ -1682,8 +1685,7 @@ void printSectionHeaders(const ObjectFile *Obj) {
 
 void printSectionContents(const ObjectFile *Obj) {
   for (const SectionRef &Section : ToolSectionFilter(*Obj)) {
-    StringRef Name;
-    error(Section.getName(Name));
+    StringRef Name = unwrapOrError(Section.getName(), Obj->getFileName());
     uint64_t BaseAddr = Section.getAddress();
     uint64_t Size = Section.getSize();
     if (!Size)
@@ -1747,11 +1749,16 @@ void printSymbolTable(const ObjectFile *O, StringRef ArchiveName,
     section_iterator Section = unwrapOrError(Symbol.getSection(), ArchiveName,
                                              FileName, ArchitectureName);
     StringRef Name;
-    if (Type == SymbolRef::ST_Debug && Section != O->section_end())
-      Section->getName(Name);
-    else
+    if (Type == SymbolRef::ST_Debug && Section != O->section_end()) {
+      if (Expected<StringRef> NameOrErr = Section->getName())
+        Name = *NameOrErr;
+      else
+        consumeError(NameOrErr.takeError());
+
+    } else {
       Name = unwrapOrError(Symbol.getName(), ArchiveName, FileName,
                            ArchitectureName);
+    }
 
     bool Global = Flags & SymbolRef::SF_Global;
     bool Weak = Flags & SymbolRef::SF_Weak;
@@ -1797,8 +1804,8 @@ void printSymbolTable(const ObjectFile *O, StringRef ArchiveName,
         StringRef SegmentName = MachO->getSectionFinalSegmentName(DR);
         outs() << SegmentName << ",";
       }
-      StringRef SectionName;
-      error(Section->getName(SectionName));
+      StringRef SectionName =
+          unwrapOrError(Section->getName(), O->getFileName());
       outs() << SectionName;
     }
 
@@ -1871,7 +1878,11 @@ void printRawClangAST(const ObjectFile *Obj) {
   Optional<object::SectionRef> ClangASTSection;
   for (auto Sec : ToolSectionFilter(*Obj)) {
     StringRef Name;
-    Sec.getName(Name);
+    if (Expected<StringRef> NameOrErr = Sec.getName())
+      Name = *NameOrErr;
+    else
+      consumeError(NameOrErr.takeError());
+
     if (Name == ClangASTSectionName) {
       ClangASTSection = Sec;
       break;
@@ -1903,7 +1914,11 @@ static void printFaultMaps(const ObjectFile *Obj) {
 
   for (auto Sec : ToolSectionFilter(*Obj)) {
     StringRef Name;
-    Sec.getName(Name);
+    if (Expected<StringRef> NameOrErr = Sec.getName())
+      Name = *NameOrErr;
+    else
+      consumeError(NameOrErr.takeError());
+
     if (Name == FaultMapSectionName) {
       FaultMapSection = Sec;
       break;