8166229: Eliminate ParNew's use of klass_or_null()

[Kim Barrett]

> On Sep 19, 2016, at 3:09 AM, Mikael Gerdin <mikael.gerdin at oracle.com> wrote:
> 
> Hi Kim,
> 
> On 2016-09-19 00:23, Kim Barrett wrote:
>> Please review this change to ParNew (the young-gen collector paired
>> with CMS), eliminating it's use of klass_or_null(), instead using
>> list_ptr_from_klass().
>> 
>> CR:
>> https://bugs.openjdk.java.net/browse/JDK-8166229
>> 
>> Webrev:
>> http://cr.openjdk.java.net/~kbarrett/8166229/webrev.00/
> 
> Looks good.
> /Mikael

Thanks!

> 
>> 
>> Testing:
>> Local jtreg tests with the following additional options:
>> -XX:+UseConcMarkSweepGC
>> -XX:-UseCompressedOops
>> -XX:-ParGCUseLocalOverflow
>> -XX:+ParGCWorkQueueOverflowALot
>> and temporary logging on the code path where klass_or_null was being
>> used, to verify testing reached the changed code.