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

[Erik Osterlund]

Hi Roman,

Thanks for the review.

/Erik

> On 17 Oct 2017, at 15:08, Roman Kennke <rkennke at redhat.com> wrote:
> 
>> 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 It will also soon be superseded by the new GC barrier interface.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
>