RFR: JDK-8222537: Avoid fetching _klass twice in TypeArrayOop::size()

[Per Liden]

Hi Roman,

I see you're pining, but I still haven't seen an answer to my initial 
question on this patch.

cheers,
Per

On 5/3/19 6:59 PM, Roman Kennke wrote:
> Ping?
> 
> Roman
> 
>> Currently, when calling TypeArrayOop::size(), we end up calling klass()
>> twice: once before calling into size_given_klass() and then again before
>> calling TypeArrayOop::object_size().
>>
>> This is currently only a minor performance nuisance.
>>
>> With upcoming Shenandoah's elimination of forwarding pointer, loading
>> klass like this is not safe anymore, and therefore we only call
>> size_given_klass(), and must avoid calling naked klass() altogether.
>>
>> Bug:
>> https://bugs.openjdk.java.net/browse/JDK-8222537
>> Webrev:
>> http://cr.openjdk.java.net/~rkennke/JDK-8222537/webrev.00/
>> Testing:
>> hotspot_gc_shenandoah with and without the prototype, hotspot/tier1
>>
>> Can I please get reviews?
>>
>> Thanks,
>> Roman
>>