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

[Erik Österlund]

Hi Per,

Thanks for the review!

/Erik

On 2018-11-20 09:34, Per Liden wrote:
> 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
>>