RFR: FinalEvac pause to turn off evacuation

[Roman Kennke]

Am 15.03.2018 um 14:52 schrieb Roman Kennke:
> We've had plenty of small and big bugs surrounding our turning off
> evacuation concurrently at the end of evacuation. And we jump through
> some hoops in C2 to insert a load-load-membar to ensure ordering of
> loading the flag and loading the fwd pointer is correct. We can forgo
> all of this by turning evac off at a safepoint always. This was
> previously difficult because the flag would also participate in
> OOM-during-evac-handling, but this is fixed now too. This patch
> implements that, and removes all the crap to support concurrently
> turning off evac:
> 
> http://cr.openjdk.java.net/~rkennke/final-evac/webrev.00/
> 
> Passes: hotspot_gc_shenandoah
> 
> Ok?
> 

Take this webrev instead:

http://cr.openjdk.java.net/~rkennke/final-evac/webrev.01/

Thanks,
Roman