[aarch64-port-dev ] RFR: 8224187 Refactor arraycopy_prologue to allow ZGC read barriers on arraycopy

[Roman Kennke]

> 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
>>>
>>