[8u] RFR: JDK-8257192: Integrate AArch64 JIT port into 8u

[Andrew Hughes]

On 14:40 Mon 30 Nov     , Andrew Haley wrote:
> On 30/11/2020 13:45, Aleksey Shipilev wrote:
> > I have only a philosophical point left: if we push this to 8u282, this means we start the clock on 
> > getting any remaining issues resolved in December before the January release. Since December is the 
> > time when a significant part of involved people take vacations, I think we are risking this quite a 
> > bit. While not exactly the concern of OpenJDK 8u Upstream, it would also mean we would need to merge 
> > this back to aarch64-port/jdk8u-shenandoah, and make sure that Shenandoah itself is not broken.
> 
> Sure, but every change we make now means we diverge further from the well-tested
> AArch64 port of 8u that's been shipping for some time.
> 
> I'm happy either way: Andrew already explained his plan with
> 
> "Just before rampdown is the best time to do this, as it always gives us
> the option to roll back to this point, without losing other 8u282 changes.
> This is what we also did with TLSv1.3. Such a rollback should be unnecessary
> though, as this port has been in production for a long time!"
> 
> -- 
> Andrew Haley  (he/him)
> Java Platform Lead Engineer
> Red Hat UK Ltd. <https://www.redhat.com>
> https://keybase.io/andrewhaley
> EAC8 43EB D3EF DB98 CC77 2FAD A5CD 6035 332F A671
> 

Yes, that was my primary concern too; we have to choose a known point to do such
a merge, and once we do, we have two copies of the code to keep in sync.

I think this is very low risk, given how long we've had it out in the wild, but if
it makes Aleksey happier, we can let it soak in 8u292. It does mean any AArch64
patches will have to be pushed to both trees between now and late January, but
it is fairly low traffic, in my experience (I've been doing the same sync to
IcedTea every cycle anyway). I can pick those across when I merge in the other
direction from 8u->aarch64/shenandoah-jdk8u.

Thanks,
-- 
Andrew :)

Senior Free Java Software Engineer
OpenJDK Package Owner
Red Hat, Inc. (http://www.redhat.com)

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