RFR: 8224187 Refactor arraycopy_prologue to allow ZGC read barriers on arraycopy

[Stuart Monteith]

Hello Roman,
   You proposal is a superset of what I've proposed, so I'm happy to
go with your patch. I can close my bug and rebase on yours.

Thanks,
   Stuart

On Mon, 20 May 2019 at 13:18, Roman Kennke <rkennke at redhat.com> wrote:
>
> > Hello Roman,
> >   I don't think there is any disagreement about Erik's proposal.
> > However, I'd like to understand what the time-frame is for Erik's
> > proposal would be before abandoning this patch.  I am aiming for ZGC
> > for aarch64 to get merged before rampdown phase 1 in mid-June in order
> > for it to be in JDK 13 as an experimental option.. I believe this
> > change is minimal, it wouldn't add any additional effort onto Erik's
> > proposal, and if nothing else brings aarch64 more in line with the
> > other platforms.
>
> Right. I would like to propose that we take it a tiny step further and do:
>
> https://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2019-May/025693.html
>
>
> Such that we (Shenandoah team) can make progress too. Then Erik can work
> on the full arraycopy GC interface without extra pressure.
>
> Roman
>
>
>
> > BR,
> >    Stuart
> >
> > On Mon, 20 May 2019 at 11:40, Roman Kennke <rkennke at redhat.com> wrote:
> >>
> >> I'd rather see Erik's proposal implemented to make the GC generate the
> >> whole path to begin with. Otherwise we'd band-aid for ZGC now, and later
> >> have to band-aid again for Shenandoah. See discussion for JDK-8223240
> >> and in your aarch64 on ZGC thread.
> >>
> >> Roman
> >>
> >>> Hello,
> >>>    On aarch64 the signature for
> >>> barrierSetAssembler::arraycopy_prologue needs to be changed in order
> >>> accept the source as well as the destination array for ZGC's barriers.
> >>>
> >>> The bug:
> >>>  https://bugs.openjdk.java.net/browse/JDK-8224187
> >>> and the patch:
> >>>   http://cr.openjdk.java.net/~smonteith/8224187/webrev.0/
> >>>
> >>>
> >>> BR,
> >>>    Stuart
> >>>
> >>
>