Merge pull request #11964 from swiftlang/cherrypick-0c0ed39

[lldb] Don't read firstSubclass and nextSiblingClass from class_rw_t

Author: JDevlieghere

lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCClassDescriptorV2.cpp

@@ -111,26 +111,23 @@ bool ClassDescriptorV2::class_rw_t::Read(Process *process, lldb::addr_t addr) {
  process->GetAddressByteSize());
 
  lldb::offset_t cursor = 0;
-
  m_flags = extractor.GetU32_unchecked(&cursor);
  m_version = extractor.GetU32_unchecked(&cursor);
  m_ro_ptr = extractor.GetAddress_unchecked(&cursor);
  if (ABISP abi_sp = process->GetABI())
  m_ro_ptr = abi_sp->FixCodeAddress(m_ro_ptr);
  m_method_list_ptr = extractor.GetAddress_unchecked(&cursor);
  m_properties_ptr = extractor.GetAddress_unchecked(&cursor);
- m_firstSubclass = extractor.GetAddress_unchecked(&cursor);
- m_nextSiblingClass = extractor.GetAddress_unchecked(&cursor);
 
  if (m_ro_ptr & 1) {
  DataBufferHeap buffer(ptr_size, '\0');
  process->ReadMemory(m_ro_ptr ^ 1, buffer.GetBytes(), ptr_size, error);
  if (error.Fail())
  return false;
- cursor = 0;
  DataExtractor extractor(buffer.GetBytes(), ptr_size,
  process->GetByteOrder(),
  process->GetAddressByteSize());
+ lldb::offset_t cursor = 0;
  m_ro_ptr = extractor.GetAddress_unchecked(&cursor);
  if (ABISP abi_sp = process->GetABI())
  m_ro_ptr = abi_sp->FixCodeAddress(m_ro_ptr);

lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCClassDescriptorV2.h

@@ -133,9 +133,6 @@ class ClassDescriptorV2 : public ObjCLanguageRuntime::ClassDescriptor {
  lldb::addr_t m_properties_ptr;
  lldb::addr_t m_protocols_ptr;
 
- ObjCLanguageRuntime::ObjCISA m_firstSubclass;
- ObjCLanguageRuntime::ObjCISA m_nextSiblingClass;
-
  bool Read(Process *process, lldb::addr_t addr);
  };