[11u] RFR: JDK-8206895: aarch64: rework error-prone cmp instuction

[Lemmond, Dan]

> BTW, we already discussed backporting it to 11 here and it was rejected
> as too risky:

I haven’t been able to find any information about the risk associated
with 8206895 (this patch), but the 8206265 thread you refer to reads to me
that a smaller, easily reviewable fix was approved for 11.0.1 due to stability
concerns right after GA, while a somewhat riskier but better fix went into 12.
If there were/are other reasons, I'd appreciate any insight you can provide.

> Please explain why this should be back-ported.

It looks like a nice stability and readability improvement to me. Given that
it's been baking since 12, I see the backport risk as minor.

Thanks,
Dan
 

On 6/11/20, 10:25 AM, "Andrew Haley" <aph at redhat.com> wrote:

    On 11/06/2020 17:53, Lemmond, Dan wrote:
    > The backport compiles without issue and passes all Tier1 Hotspot tests.
    
    Please explain why this should be back-ported.
    
    BTW, we already discussed backporting it to 11 here and it was rejected
    as too risky:
    
    http://mail.openjdk.java.net/pipermail/hotspot-dev/2018-July/033437.html
    
    Unless this actually fixes a bug, it looks dubious as a backport.
    
    --
    Andrew Haley  (he/him)
    Java Platform Lead Engineer
    Red Hat UK Ltd. <https://www.redhat.com>
    https://keybase.io/andrewhaley
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