RFR (T) 8242898: Clean up InstanceKlass::_array_klasses

[Ioi Lam]

On 4/29/20 2:41 PM, coleen.phillimore at oracle.com wrote:
>
>
> On 4/29/20 12:15 PM, Ioi Lam wrote:
>> Hi Coleen,
>>
>> This looks good, but should we also rename array_klasses to 
>> array_klass, since in most cases we are talking about one klass 
>> instead of many klasses?
>
> It is many classes because they're all linked through _array_klasses 
> through the higher_dimension(), so it's essentially more than one.
>

But this plural usage is inconsistent with other places we use link 
lists. E.g., klass.hpp

   // First subclass (NULL if none); _subklass->next_sibling() is next one
   Klass* volatile _subklass;
   // Sibling link (or NULL); links all subklasses of a klass
   Klass* volatile _next_sibling;
   // All klasses loaded by a class loader are chained through these links
   Klass*      _next_link;

and we don't use _supers even if you can use _super to walk all super 
classes.

   Klass*      _super;


Thanks
- Ioi


> So I'd rather leave the name as is.
> Thanks,
> Coleen
>>
>> The plural makes sense only in places like this:
>>
>>
>> 1625 void InstanceKlass::array_klasses_do(void f(Klass* k, TRAPS), 
>> TRAPS) {
>> 1626   if (array_klass() != NULL)
>> 1627     array_klass()->array_klasses_do(f, THREAD);
>> 1628 }
>>
>> Thanks
>> - Ioi
>>
>>
>> On 4/29/20 6:06 AM, coleen.phillimore at oracle.com wrote:
>>>
>>>
>>> On 4/29/20 8:44 AM, David Holmes wrote:
>>>> Hi Coleen,
>>>>
>>>> On 29/04/2020 10:11 pm, coleen.phillimore at oracle.com wrote:
>>>>> Summary: Use more specific ObjArrayKlass type.
>>>>>
>>>>> This avoids some casts.  Tested with tier1-3.
>>>>>
>>>>> open webrev at 
>>>>> http://cr.openjdk.java.net/~coleenp/2020/8242898.01/webrev
>>>>> bug link https://bugs.openjdk.java.net/browse/JDK-8242898
>>>>
>>>> This looks fine to me.
>>>>
>>>> I have to wonder why this was not defined this way all along?
>>>
>>> It was likely klassOop and stayed that way until Ioi noticed.
>>> Thanks,
>>> Coleen
>>>>
>>>> Thanks,
>>>> David
>>>>
>>>>> thanks,
>>>>> Coleen
>>>
>>
>