RFR: 8234010: ZGC: Change ZResurrection to use Atomic::load/store

[erik.osterlund at oracle.com]

Hi Stefan,

Looks good.

Thanks,
/Erik

On 11/21/19 2:24 PM, Stefan Karlsson wrote:
> Hi all,
>
> Please review this patch to change ZResurrection to use Atomic::load 
> and Atomic::store.
>
> https://cr.openjdk.java.net/~stefank/8234010/webrev.01/
> https://bugs.openjdk.java.net/browse/JDK-8234010
>
> Previously, ZResurrection::is_blocked() and ZResurrection::unblock() 
> used loadload and storestore barriers to synchronize between the GC 
> and mutator load barriers.
>
> JDK-8230661 changed so that we always perform a handshake before the 
> ZResurrection::unblock() call.
>
> After that change we can rely on the handshake to perform the 
> necessary synchronization, and we can change the implementation to use 
> Atomic::load and Atomic::store.
>
> Tested with tier1-7
>
> Thanks,
> StefanK