hotpot java虚拟机Class对象是放在 方法区 还是堆中 ？

instanceKlassHandle ClassFileParser::parseClassFile(Symbol* name,
                                                    ClassLoaderData* loader_data,
                                                    Handle protection_domain,
                                                    KlassHandle host_klass,
                                                    GrowableArray<Handle>* cp_patches,
                                                    TempNewSymbol& parsed_name,
                                                    bool verify,
                                                    TRAPS){
/***ignore***/
// LINE: 4077
    // Allocate mirror and initialize static fields
    java_lang_Class::create_mirror(this_klass, protection_domain, CHECK_(nullHandle));
/***ignore***/}

oop java_lang_Class::create_mirror(KlassHandle k, Handle protection_domain, TRAPS) {
  assert(k->java_mirror() == NULL, "should only assign mirror once");
  // Use this moment of initialization to cache modifier_flags also,
  // to support Class.getModifiers().  Instance classes recalculate
  // the cached flags after the class file is parsed, but before the
  // class is put into the system dictionary.
  int computed_modifiers = k->compute_modifier_flags(CHECK_0);
  k->set_modifier_flags(computed_modifiers);
  // Class_klass has to be loaded because it is used to allocate
  // the mirror.
  if (SystemDictionary::Class_klass_loaded()) {
    // Allocate mirror (java.lang.Class instance)
    Handle mirror = InstanceMirrorKlass::cast(SystemDictionary::Class_klass())->allocate_instance(k, CHECK_0);

    InstanceMirrorKlass* mk = InstanceMirrorKlass::cast(mirror->klass());
    java_lang_Class::set_static_oop_field_count(mirror(), mk->compute_static_oop_field_count(mirror()));

    // It might also have a component mirror.  This mirror must already exist.
    if (k->oop_is_array()) {
      Handle comp_mirror;
      if (k->oop_is_typeArray()) {
        BasicType type = TypeArrayKlass::cast(k())->element_type();
        comp_mirror = Universe::java_mirror(type);
      } else {
        assert(k->oop_is_objArray(), "Must be");
        Klass* element_klass = ObjArrayKlass::cast(k())->element_klass();
        assert(element_klass != NULL, "Must have an element klass");
          comp_mirror = element_klass->java_mirror();
      }
      assert(comp_mirror.not_null(), "must have a mirror");

        // Two-way link between the array klass and its component mirror:
      ArrayKlass::cast(k())->set_component_mirror(comp_mirror());
      set_array_klass(comp_mirror(), k());
    } else {
      assert(k->oop_is_instance(), "Must be");

      // Allocate a simple java object for a lock.
      // This needs to be a java object because during class initialization
      // it can be held across a java call.
      typeArrayOop r = oopFactory::new_typeArray(T_INT, 0, CHECK_NULL);
      set_init_lock(mirror(), r);

      // Set protection domain also
      set_protection_domain(mirror(), protection_domain());

      // Initialize static fields
      InstanceKlass::cast(k())->do_local_static_fields(&initialize_static_field, CHECK_NULL);
    }
    return mirror();
  } else {
    if (fixup_mirror_list() == NULL) {
      GrowableArray<Klass*>* list =
       new (ResourceObj::C_HEAP, mtClass) GrowableArray<Klass*>(40, true);
      set_fixup_mirror_list(list);
    }
    fixup_mirror_list()->push(k());
    return NULL;
  }
}

void Universe::initialize_basic_type_mirrors(TRAPS) {
    assert(_int_mirror==NULL, "basic type mirrors already initialized");
    _int_mirror     =
      java_lang_Class::create_basic_type_mirror("int",    T_INT, CHECK);
    _float_mirror   =
      java_lang_Class::create_basic_type_mirror("float",  T_FLOAT,   CHECK);
    _double_mirror  =
      java_lang_Class::create_basic_type_mirror("double", T_DOUBLE,  CHECK);
    _byte_mirror    =
      java_lang_Class::create_basic_type_mirror("byte",   T_BYTE, CHECK);
    _bool_mirror    =
      java_lang_Class::create_basic_type_mirror("boolean",T_BOOLEAN, CHECK);
    _char_mirror    =
      java_lang_Class::create_basic_type_mirror("char",   T_CHAR, CHECK);
    _long_mirror    =
      java_lang_Class::create_basic_type_mirror("long",   T_LONG, CHECK);
    _short_mirror   =
      java_lang_Class::create_basic_type_mirror("short",  T_SHORT,   CHECK);
    _void_mirror    =
      java_lang_Class::create_basic_type_mirror("void",   T_VOID, CHECK);

    _mirrors[T_INT]     = _int_mirror;
    _mirrors[T_FLOAT]   = _float_mirror;
    _mirrors[T_DOUBLE]  = _double_mirror;
    _mirrors[T_BYTE]    = _byte_mirror;
    _mirrors[T_BOOLEAN] = _bool_mirror;
    _mirrors[T_CHAR]    = _char_mirror;
    _mirrors[T_LONG]    = _long_mirror;
    _mirrors[T_SHORT]   = _short_mirror;
    _mirrors[T_VOID]    = _void_mirror;
  //_mirrors[T_OBJECT]  = InstanceKlass::cast(_object_klass)->java_mirror();
  //_mirrors[T_ARRAY]   = InstanceKlass::cast(_object_klass)->java_mirror();
}

oop java_lang_Class::create_basic_type_mirror(const char* basic_type_name, BasicType type, TRAPS) {
  // This should be improved by adding a field at the Java level or by
  // introducing a new VM klass (see comment in ClassFileParser)
  oop java_class = InstanceMirrorKlass::cast(SystemDictionary::Class_klass())->allocate_instance(NULL, CHECK_0);
  if (type != T_VOID) {
    Klass* aklass = Universe::typeArrayKlassObj(type);
    assert(aklass != NULL, "correct bootstrap");
    set_array_klass(java_class, aklass);
  }
#ifdef ASSERT
  InstanceMirrorKlass* mk = InstanceMirrorKlass::cast(SystemDictionary::Class_klass());
  assert(java_lang_Class::static_oop_field_count(java_class) == 0, "should have been zeroed by allocation");
#endif
  return java_class;
}

instanceOop InstanceMirrorKlass::allocate_instance(KlassHandle k, TRAPS) {
  // Query before forming handle.
  int size = instance_size(k);
  KlassHandle h_k(THREAD, this);
  instanceOop i = (instanceOop) CollectedHeap::Class_obj_allocate(h_k, size, k, CHECK_NULL);
  return i;
}

oop CollectedHeap::Class_obj_allocate(KlassHandle klass, int size, KlassHandle real_klass, TRAPS) {
  debug_only(check_for_valid_allocation_state());
  assert(!Universe::heap()->is_gc_active(), "Allocation during gc not allowed");
  assert(size >= 0, "int won't convert to size_t");
  HeapWord* obj;
    assert(ScavengeRootsInCode > 0, "must be");
    obj = common_mem_allocate_init(real_klass, size, CHECK_NULL);
  post_allocation_setup_common(klass, obj);
  assert(Universe::is_bootstrapping() ||
         !((oop)obj)->is_array(), "must not be an array");
  NOT_PRODUCT(Universe::heap()->check_for_bad_heap_word_value(obj, size));
  oop mirror = (oop)obj;

  java_lang_Class::set_oop_size(mirror, size);

  // Setup indirections
  if (!real_klass.is_null()) {
    java_lang_Class::set_klass(mirror, real_klass());
    real_klass->set_java_mirror(mirror);
  }

  InstanceMirrorKlass* mk = InstanceMirrorKlass::cast(mirror->klass());
  assert(size == mk->instance_size(real_klass), "should have been set");

  // notify jvmti and dtrace
  post_allocation_notify(klass, (oop)obj);

  return mirror;
}