[DWARF] - Remove unused code.

[grimar]

Summary

This was added in D32779, but I think it was unused from begining,
because Name (prev name) variable is never accessed after Obj.mapDebugSectionName() call.
Looks we can remove it.

[wolfgangp]

Yikes, looks like you found a bug. The original idea was to provide a generic mechanism to map platform specific debug section names to DWARF standard names, for example for Mach-O, which limits section names to 16 characters. The Mach-O section name for .debug_str_offsets is debug_str_offs, so I was trying to map this back to debug_str_offsets (all the leading '_' and '.'s are removed at this point). The call should have gone before the "if (StringRef *SectionData =" line a few lines above, otherwise the call the MapSectionToMember() would fail for Mach-O object files with a debug_str_off section. Nobody is generating one yet, so nobody will hit it, but it's there. My bad, of course, for not adding a test for Mach-O in the first place.

Please don't commit this, I will fix it in a different review and add a test for Mach-O.

[grimar]

In D35193#803968, @wolfgangp wrote:

Yikes, looks like you found a bug. The original idea was to provide a generic mechanism to map platform specific debug section names to DWARF standard names, for example for Mach-O, which limits section names to 16 characters. The Mach-O section name for .debug_str_offsets is debug_str_offs, so I was trying to map this back to debug_str_offsets (all the leading '_' and '.'s are removed at this point). The call should have gone before the "if (StringRef *SectionData =" line a few lines above, otherwise the call the MapSectionToMember() would fail for Mach-O object files with a debug_str_off section. Nobody is generating one yet, so nobody will hit it, but it's there. My bad, of course, for not adding a test for Mach-O in the first place.

Please don't commit this, I will fix it in a different review and add a test for Mach-O.

Ok, thanks for explanation, I am abandoning this one then.

include/llvm/Object/MachO.h

public:
   static Triple getArchTriple(uint32_t CPUType, uint32_t CPUSubType,
                               const char **McpuDefault = nullptr,
                               const char **ArchFlag = nullptr);
   static bool isValidArch(StringRef ArchFlag);
   static Triple getHostArch();
 
   bool isRelocatableObject() const override;
 
-  StringRef mapDebugSectionName(StringRef Name) const override;
-
   bool hasPageZeroSegment() const { return HasPageZeroSegment; }
 
   static bool classof(const Binary *v) {
     return v->isMachO();
   }
 
   static uint32_t
   getVersionMinMajor(MachO::version_min_command &C, bool SDK) {

include/llvm/Object/ObjectFile.h

virtual std::error_code getPlatformFlags(unsigned &Result) const {
     return object_error::invalid_file_type;
   }
 
   virtual std::error_code
     getBuildAttributes(ARMAttributeParser &Attributes) const {
       return std::error_code();
     }
 
-  /// Maps a debug section name to a standard DWARF section name.
-  virtual StringRef mapDebugSectionName(StringRef Name) const { return Name; }
-
   /// True if this is a relocatable object (.o/.obj).
   virtual bool isRelocatableObject() const = 0;
 
   /// @returns Pointer to ObjectFile subclass to handle this type of object.
   /// @param ObjectPath The path to the object file. ObjectPath.isObject must
   ///        return true.
   /// @brief Create ObjectFile from path.
   static Expected<OwningBinary<ObjectFile>>

lib/DebugInfo/DWARF/DWARFContext.cpp

for (const SectionRef &Section : Obj.sections()) {
     } else if (Name == "debug_types") {
       // Find debug_types data by section rather than name as there are
       // multiple, comdat grouped, debug_types sections.
       TypesSections[Section].Data = Data;
     } else if (Name == "debug_types.dwo") {
       TypesDWOSections[Section].Data = Data;
     }
 
-    // Map platform specific debug section names to DWARF standard section
-    // names.
-    Name = Obj.mapDebugSectionName(Name);
-
     if (RelocatedSection == Obj.section_end())
       continue;
 
     StringRef RelSecName;
     StringRef RelSecData;
     RelocatedSection->getName(RelSecName);
 
     // If the section we're relocating was relocated already by the JIT,

lib/Object/MachOObjectFile.cpp

if (Magic == "\xFE\xED\xFA\xCF")
     return MachOObjectFile::create(Buffer, false, true,
                                    UniversalCputype, UniversalIndex);
   if (Magic == "\xCF\xFA\xED\xFE")
     return MachOObjectFile::create(Buffer, true, true,
                                    UniversalCputype, UniversalIndex);
   return make_error<GenericBinaryError>("Unrecognized MachO magic number",
                                         object_error::invalid_file_type);
 }
-
-StringRef MachOObjectFile::mapDebugSectionName(StringRef Name) const {
-  return StringSwitch<StringRef>(Name)
-      .Case("debug_str_offs", "debug_str_offsets")
-      .Default(Name);
-}