RFR: 8212992: Change mirror accessor in Klass::verify_on() to use AS_NO_KEEPALIVE

[Per Liden]

Looks good!

/Per

On 11/19/18 3:30 PM, Erik Österlund wrote:
> Ping.
> 
> I no longer strictly need this as verification was moved to a later 
> stage where the problematic assert goes away. But I still think we 
> should only peek at the mirror here anyway.
> 
> Thanks,
> /Erik
> 
> On 2018-10-25 20:45, Erik Österlund wrote:
>> Hi,
>>
>> The Klass::verify_on() is sometimes called on unloading klasses. It 
>> then reads a dead mirror, without using AS_NO_KEEPALIVE, which can 
>> make GC barriers feel like :C (because that should *never* normally 
>> happen). In order to make barriers happy, AS_NO_KEEPALIVE should be 
>> used when loading dead oops.
>>
>> Webrev:
>> http://cr.openjdk.java.net/~eosterlund/8212992/webrev.00/
>>
>> Bug:
>> https://bugs.openjdk.java.net/browse/JDK-8212992
>>
>> Thanks,
>> /Erik
>