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

[Erik Österlund]

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