src/hotspot/share/classfile/classFileParser.cpp

*** 1544,1554 ****
  
    int num_injected = 0;
    const InjectedField* const injected = JavaClasses::get_injected(_class_name,
                                                                    &num_injected);
  
!   const int total_fields = length + num_injected + (is_value_type ? 1 : 0);
  
    // The field array starts with tuples of shorts
    // [access, name index, sig index, initial value index, byte offset].
    // A generic signature slot only exists for field with generic
    // signature attribute. And the access flag is set with
--- 1544,1554 ----
  
    int num_injected = 0;
    const InjectedField* const injected = JavaClasses::get_injected(_class_name,
                                                                    &num_injected);
  
!   const int total_fields = length + num_injected + (is_value_type ? 2 : 0);
  
    // The field array starts with tuples of shorts
    // [access, name index, sig index, initial value index, byte offset].
    // A generic signature slot only exists for field with generic
    // signature attribute. And the access flag is set with
*** 1574,1583 ****
--- 1574,1584 ----
                                                total_fields * (FieldInfo::field_slots + 1));
  
    // The generic signature slots start after all other fields' data.
    int generic_signature_slot = total_fields * FieldInfo::field_slots;
    int num_generic_signature = 0;
+   int instance_fields_count = 0;
    for (int n = 0; n < length; n++) {
      // access_flags, name_index, descriptor_index, attributes_count
      cfs->guarantee_more(8, CHECK);
  
      jint recognized_modifiers = JVM_RECOGNIZED_FIELD_MODIFIERS;
*** 1614,1623 ****
--- 1615,1625 ----
              " ACC_FLATTENABLE cannot be specified for an array",
              name->as_C_string(), sig->as_klass_external_name(), CHECK);
        }
        _has_flattenable_fields = true;
      }
+     if (!access_flags.is_static()) instance_fields_count++;
  
      u2 constantvalue_index = 0;
      bool is_synthetic = false;
      u2 generic_signature_index = 0;
      const bool is_static = access_flags.is_static();
*** 1721,1731 ****
        index++;
      }
    }
  
    if (is_value_type) {
-     index = length + num_injected;
      FieldInfo* const field = FieldInfo::from_field_array(fa, index);
      field->initialize(JVM_ACC_FIELD_INTERNAL | JVM_ACC_STATIC,
                        vmSymbols::default_value_name_enum,
                        vmSymbols::java_lang_Object_enum,
                        0);
--- 1723,1732 ----
*** 1733,1742 ****
--- 1734,1756 ----
      const FieldAllocationType atype = fac->update(true, type, false);
      field->set_allocation_type(atype);
      index++;
    }
  
+   if (is_value_type && instance_fields_count == 0) {
+     _is_empty_value = true;
+     FieldInfo* const field = FieldInfo::from_field_array(fa, index);
+     field->initialize(JVM_ACC_FIELD_INTERNAL,
+         vmSymbols::empty_marker_name_enum,
+         vmSymbols::byte_signature_enum,
+         0);
+     const BasicType type = FieldType::basic_type(vmSymbols::byte_signature());
+     const FieldAllocationType atype = fac->update(false, type, false);
+     field->set_allocation_type(atype);
+     index++;
+   }
+ 
    assert(NULL == _fields, "invariant");
  
    _fields =
      MetadataFactory::new_array<u2>(_loader_data,
                                     index * FieldInfo::field_slots + num_generic_signature,
*** 5791,5800 ****
--- 5805,5817 ----
    ik->set_should_verify_class(_need_verify);
  
    // Not yet: supers are done below to support the new subtype-checking fields
    ik->set_nonstatic_field_size(_field_info->nonstatic_field_size);
    ik->set_has_nonstatic_fields(_field_info->has_nonstatic_fields);
+   if (_is_empty_value) {
+     ik->set_is_empty_value();
+   }
    assert(_fac != NULL, "invariant");
    ik->set_static_oop_field_count(_fac->count[STATIC_OOP] + _fac->count[STATIC_FLATTENABLE]);
  
    // this transfers ownership of a lot of arrays from
    // the parser onto the InstanceKlass*
*** 5959,5971 ****
        ValueKlass::cast(ik)->set_default_value_offset(ik->field_offset(i));
      }
    }
  
    if (is_value_type()) {
!     ValueKlass::cast(ik)->set_alignment(_alignment);
!     ValueKlass::cast(ik)->set_first_field_offset(_first_field_offset);
!     ValueKlass::cast(ik)->set_exact_size_in_bytes(_exact_size_in_bytes);
      ValueKlass::cast(ik)->initialize_calling_convention(CHECK);
    }
  
    ClassLoadingService::notify_class_loaded(ik, false /* not shared class */);
  
--- 5976,5993 ----
        ValueKlass::cast(ik)->set_default_value_offset(ik->field_offset(i));
      }
    }
  
    if (is_value_type()) {
!     ValueKlass* vk = ValueKlass::cast(ik);
!     if (UseNewLayout) {
!       vk->set_alignment(_alignment);
!       vk->set_first_field_offset(_first_field_offset);
!       vk->set_exact_size_in_bytes(_exact_size_in_bytes);
!     } else {
!       vk->set_first_field_offset(vk->first_field_offset_old());
!     }
      ValueKlass::cast(ik)->initialize_calling_convention(CHECK);
    }
  
    ClassLoadingService::notify_class_loaded(ik, false /* not shared class */);
  
*** 6155,6164 ****
--- 6177,6187 ----
    _relax_verify(false),
    _has_nonstatic_concrete_methods(false),
    _declares_nonstatic_concrete_methods(false),
    _has_final_method(false),
    _has_flattenable_fields(false),
+   _is_empty_value(false),
    _has_finalizer(false),
    _has_empty_finalizer(false),
    _has_vanilla_constructor(false),
    _max_bootstrap_specifier_index(-1) {