ObjectFile: remove ReadSectionData/MemoryMapSectionData mutual recursion

[labath]

Summary

These two functions were calling each other, while handling different
branches of the if(IsInMemory()). I am assuming this had a reason at
some point in the past, but right now it's just confusing.

I resolve this by removing the MemoryMapSectionData function and
inlining the !IsInMemory branch into ReadSectionData. There isn't
anything mmap-related in this function anyway, as the decision whether
to mmap is handled at a higher level.

This is a preparatory step to make ObjectFileELF be able to decompress
compressed sections (I want to make sure that all calls reading section
data are routed through a single piece of code).

[davide]

LGTM.

[clayborg]

This was left over from before we mmap'ed the entire object file into memory. Removing it is fine as the backing DataBufferSP for the object file will be mmaped or not depending on where the file was loaded from and if the section isn't compressed, we will just hand out a shared slice of the object file data.

lldb/trunk/include/lldb/Symbol/ObjectFile.h

public:
 
   virtual size_t ReadSectionData(Section *section,
                                  lldb::offset_t section_offset, void *dst,
                                  size_t dst_len);
 
   virtual size_t ReadSectionData(Section *section,
                                  DataExtractor &section_data);
 
-  size_t MemoryMapSectionData(Section *section,
-                              DataExtractor &section_data);
-
   bool IsInMemory() const { return m_memory_addr != LLDB_INVALID_ADDRESS; }
 
   // Strip linker annotations (such as @@VERSION) from symbol names.
   virtual llvm::StringRef
   StripLinkerSymbolAnnotations(llvm::StringRef symbol_name) const {
     return symbol_name;
   }
 

lldb/trunk/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp

 
 void SymbolFileDWARF::InitializeObject() {
   ModuleSP module_sp(m_obj_file->GetModule());
   if (module_sp) {
     const SectionList *section_list = module_sp->GetSectionList();
     Section *section =
         section_list->FindSectionByName(GetDWARFMachOSegmentName()).get();
 
-    // Memory map the DWARF mach-o segment so we have everything mmap'ed
-    // to keep our heap memory usage down.
     if (section)
-      m_obj_file->MemoryMapSectionData(section, m_dwarf_data);
+      m_obj_file->ReadSectionData(section, m_dwarf_data);
   }
 
   get_apple_names_data();
   if (m_data_apple_names.m_data.GetByteSize() > 0) {
     m_apple_names_ap.reset(new DWARFMappedHash::MemoryTable(
         m_data_apple_names.m_data, get_debug_str_data(), ".apple_names"));
     if (m_apple_names_ap->IsValid())
       m_using_apple_tables = true;

lldb/trunk/source/Symbol/ObjectFile.cpp

if (process_sp) {
         }
       }
     }
     return GetData(section->GetFileOffset(), section->GetFileSize(),
                    section_data);
   } else {
     // The object file now contains a full mmap'ed copy of the object file data,
     // so just use this
-    return MemoryMapSectionData(section, section_data);
-  }
-}
-
-size_t ObjectFile::MemoryMapSectionData(Section *section,
-                                        DataExtractor &section_data) {
-  // If some other objectfile owns this data, pass this to them.
-  if (section->GetObjectFile() != this)
-    return section->GetObjectFile()->MemoryMapSectionData(section,
-                                                          section_data);
-
-  if (IsInMemory()) {
-    return ReadSectionData(section, section_data);
-  } else {
     if (!section->IsRelocated())
       RelocateSection(section);
 
-    // The object file now contains a full mmap'ed copy of the object file data,
-    // so just use this
     return GetData(section->GetFileOffset(), section->GetFileSize(),
                    section_data);
   }
 }
 
 bool ObjectFile::SplitArchivePathWithObject(const char *path_with_object,
                                             FileSpec &archive_file,
                                             ConstString &archive_object,