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

[Per Liden]

Looks good!

/Per

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