RFR (S): 8191567: Refactor ciInstanceKlass G1 keep alive barrier to use Access API.

[Roman Kennke]

> Hi Roman,
> 
> On 2017-11-24 17:25, Roman Kennke wrote:
>> Am 24.11.2017 um 17:22 schrieb Erik Österlund:
>>> Hi,
>>>
>>> When creating a ciInstanceKlass handle, G1 might need a SATB barrier 
>>> to keep "peeked" weak klass pointers alive during marking.
>>> This should now be done with the Access API instead of manual calls 
>>> to the G1 SATB barrier.
>>>
>>> Bug:
>>> https://bugs.openjdk.java.net/browse/JDK-8191567
>>>
>>> Webrev:
>>> http://cr.openjdk.java.net/~eosterlund/8191567/webrev.00/
>>>
>>> Thanks,
>>> /Erik
>>
>> Looks good.
> 
> Thanks for the review.
> 
>> There are many more places where G1SATBCardTableModRefBS::enqueue() is 
>> callled from shared code that would require the same treatment. Are 
>> you planning to take them one by one? Otherwise, maybe squeeze them 
>> all into this patch too because it's related and similar?
> 
> I think I would prefer to have a few small well contained RFEs compared 
> to one very large one, unless people prefer the large change approach.

I am ok with whatever works best for you :-)

Roman