[aarch64-port-dev ] RFR: 8243339: AArch64: Obsolete UseBarriersForVolatile option

[Andrew Haley]

On 5/14/20 11:07 AM, Xiaohong Gong wrote:
> Hi Andrew,
>
> Thanks for having a look at it!
>
>  > On 5/14/20 10:37 AM, Andrew Haley wrote:
>  > > On 5/14/20 9:48 AM, Andrew Dinn wrote:
>  > >> Just for references a direct link to the webrev, issue and CSR
>  > are:
>  > >>
>  > >>   https://cr.openjdk.java.net/~xgong/rfr/8243339/webrev.00/
>  > >>   https://bugs.openjdk.java.net/browse/JDK-8243339
>  > >>   https://bugs.openjdk.java.net/browse/JDK-8243456
>  > >>
>  > >> The webrev looks fine to me. Nice work, thank you!
>  > >
>  > > There's a problem with C1: we generate unnecessary DMBs if
>  > > we're using TieredStopAtLevel=1 or if we only have the client
>  > > compiler. This is a performance regression, so I reject this
>  > > patch.
>  >
>  > There are similar regressoins in the interpreter.
>
> Yes, I agree with you that regressions exist for interpreter and
> client compiler.  So do you think if it's better to add the
> conditions to add DMBs for C1 and interpreter?  How about just
> excluding the scenario like "interpreter only", "client compiler
> only" and "TieredStopAtLevel=1" ?

Yes, I think so. Is there some way simply to ask the question "Are we
using C2 or JVMCI compilers?" That's what we need to know.

-- 
Andrew Haley  (he/him)
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
https://keybase.io/andrewhaley
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