RFR (S): 8189355: Cleanup of BarrierSet barrier functions

[Roman Kennke]

Am 17.10.2017 um 12:27 schrieb Erik Österlund:
> Hi,
>
> The BarrierSet class has a bunch of unused or used in a seemingly 
> nonsense way code. Some methods are used but only used in assertion, 
> and are expected to return true (the has_*_opt methods). Others 
> describe barriers that are never called from anywhere. This might have 
> made sense at some point, but arguably does not any more. There is 
> also an enum called Flags not referenced from anywhere.
>
> I would also like to get rid of devirtualize_reference_writes() which 
> devirtualizes calls to the post-write barrier for card marking 
> specifically by loading and comparing the type of barrier set. I have 
> run a bunch of benchmarks and this optimization did not seem to 
> provide any benefit. It will also soon be superseded by the new GC 
> barrier interface.
>
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8189355
>
> Webrev:
> http://cr.openjdk.java.net/~eosterlund/8189355/webrev.00/
>
> Thanks,
> /Erik

Oh yes! This looks like a very long overdue cleanup.

Patch looks good to me!

Roman