[NFC][llvm-dwarfdump] Always use 'const Twine &'

[djtodoro]

Summary

According to the Twine.h comment, the Twines should only be used as const references in arguments.

[jhenderson]

LGTM, assuming this builds cleanly. I don't pretend to be an expert on Twine though, so somebody with more experience with it might want to give their opinion first.

[djtodoro]

-Rebasing

[probinson]

Twine can be the root of an arbitrary tree, and is not intended to be copied, the way StringRef is. Passing by const ref is correct.
LGTM.

[djtodoro]

-Reorder the patches from the stack

[djtodoro]

Thanks for the reviews, I'll land this.

llvm/tools/llvm-dwarfdump/Statistics.cpp

 ///
 /// Do the impossible and reduce the quality of the debug info down to a few
 /// numbers. The idea is to condense the data into numbers that can be tracked
 /// over time to identify trends in newer compiler versions and gauge the effect
 /// of particular optimizations. The raw numbers themselves are not particularly
 /// useful, only the delta between compiling the same program with different
 /// compilers is.
 bool collectStatsForObjectFile(ObjectFile &Obj, DWARFContext &DICtx,
-                               Twine Filename, raw_ostream &OS) {
+                               const Twine &Filename, raw_ostream &OS) {
   StringRef FormatName = Obj.getFileFormatName();
   GlobalStats GlobalStats;
   LocationStats LocStats;
   StringMap<PerFunctionStats> Statistics;
   for (const auto &CU : static_cast<DWARFContext *>(&DICtx)->compile_units())
     if (DWARFDie CUDie = CU->getNonSkeletonUnitDIE(false))
       collectStatsRecursive(CUDie, "/", "g", 0, 0, Statistics, GlobalStats,
                             LocStats);

llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp

for (auto Arch : ArchFilters) {
       // Match as name.
       if (MachO->getArchTriple().getArchName() == Triple(Arch).getArchName())
         return true;
     }
   }
   return false;
 }
 
-using HandlerFn = std::function<bool(ObjectFile &, DWARFContext &DICtx, Twine,
-                                     raw_ostream &)>;
+using HandlerFn = std::function<bool(ObjectFile &, DWARFContext &DICtx,
+                                     const Twine &, raw_ostream &)>;
 
 /// Print only DIEs that have a certain name.
 static bool filterByName(const StringSet<> &Names, DWARFDie Die,
                          StringRef NameRef, raw_ostream &OS) {
   std::string Name =
       (IgnoreCase && !UseRegex) ? NameRef.lower() : NameRef.str();
   if (UseRegex) {
     // Match regular expression.
static bool lookup(ObjectFile &Obj, DWARFContext &DICtx, uint64_t Address,
   if (DILineInfo LineInfo = DICtx.getLineInfoForAddress(
           {Lookup, object::SectionedAddress::UndefSection}))
     LineInfo.dump(OS);
 
   return true;
 }
 
 bool collectStatsForObjectFile(ObjectFile &Obj, DWARFContext &DICtx,
-                               Twine Filename, raw_ostream &OS);
+                               const Twine &Filename, raw_ostream &OS);
 
-static bool dumpObjectFile(ObjectFile &Obj, DWARFContext &DICtx, Twine Filename,
-                           raw_ostream &OS) {
+static bool dumpObjectFile(ObjectFile &Obj, DWARFContext &DICtx,
+                           const Twine &Filename, raw_ostream &OS) {
   logAllUnhandledErrors(DICtx.loadRegisterInfo(Obj), errs(),
                         Filename.str() + ": ");
   // The UUID dump already contains all the same information.
   if (!(DumpType & DIDT_UUID) || DumpType == DIDT_All)
     OS << Filename << ":\tfile format " << Obj.getFileFormatName() << '\n';
 
   // Handle the --lookup option.
   if (Lookup)
static bool dumpObjectFile(ObjectFile &Obj, DWARFContext &DICtx,
   }
 
   // Dump the complete DWARF structure.
   DICtx.dump(OS, getDumpOpts(), DumpOffsets);
   return true;
 }
 
 static bool verifyObjectFile(ObjectFile &Obj, DWARFContext &DICtx,
-                             Twine Filename, raw_ostream &OS) {
+                             const Twine &Filename, raw_ostream &OS) {
   // Verify the DWARF and exit with non-zero exit status if verification
   // fails.
   raw_ostream &stream = Quiet ? nulls() : OS;
   stream << "Verifying " << Filename.str() << ":\tfile format "
   << Obj.getFileFormatName() << "\n";
   bool Result = DICtx.verify(stream, getDumpOpts());
   if (Result)
     stream << "No errors.\n";