[EXTERNAL] Re: RFR(M): 8248190: PPC: Enable Power10 system and use new byte-reverse instructions

[Doerr, Martin]

Hi Thomas,

I understand your point. My concern is that it may become a more political discussion how to handle CSR for PPC64 flags and I don't want to delay Jose's change for that. There are already other changes in the pipe which build on top of it.

It will probably be us to handle and approve CSR requests for platforms which are maintained by SAP. We haven't done this so far. We are still handling such flags in a less formal way.
I don't know how other non-Oracle platforms are handled.

Best regards,
Martin


> -----Original Message-----
> From: Thomas Schatzl <thomas.schatzl at oracle.com>
> Sent: Freitag, 21. August 2020 17:12
> To: Doerr, Martin <martin.doerr at sap.com>; joserz at linux.ibm.com
> Cc: hotspot-compiler-dev at openjdk.java.net
> Subject: Re: [EXTERNAL] Re: RFR(M): 8248190: PPC: Enable Power10 system
> and use new byte-reverse instructions
> 
> Hi,
> 
> On 21.08.20 17:06, Doerr, Martin wrote:
> > Hi Thomas,
> >
> > I agree with you in general. However, all PPC64 specific platform flags are
> "product" at the moment.
> > Most of them should probably be "diagnostic". We should fix that at some
> point of time.
> > But for now, I'm ok with Jose's webrev since it's consistent with the other
> PPC64 flags.
> >
> 
>    I was merely pointing out what the rule is, that has not been a veto
> for the patch (which I haven't reviewed btw). If you want to go ahead
> with that for consistency's sake, with a plan to fix this I can see your
> point of keeping it.
> 
> Thanks,
>    Thomas
> 
> > Best regards,
> > Martin
> >
> >
> >> -----Original Message-----
> >> From: hotspot-compiler-dev <hotspot-compiler-dev-
> >> retn at openjdk.java.net> On Behalf Of Thomas Schatzl
> >> Sent: Freitag, 21. August 2020 15:45
> >> To: joserz at linux.ibm.com
> >> Cc: hotspot-compiler-dev at openjdk.java.net
> >> Subject: Re: [EXTERNAL] Re: RFR(M): 8248190: PPC: Enable Power10
> system
> >> and use new byte-reverse instructions
> >>
> >> Hi,
> >>
> >> On 21.08.20 15:37, joserz at linux.ibm.com wrote:
> >>> Hello!
> >>>
> >>> On Fri, Aug 21, 2020 at 10:04:38AM +0200, Thomas Schatzl wrote:
> >>>> Hi,
> >>>>
> >>>> On 21.08.20 04:33, Michihiro Horie wrote:
> >>>>>
> >>>>> Hi Jose,
> >>>>>
> >>>>> One thing I noticed is a misaligned backslash in globals_ppc.hpp.
> >>>>> Otherwise, the change looks good!
> >>>>>
> >>>>>       /* special instructions */
> >>>>> \
> >>>>> +  product(bool, UseByteReverseInstructions, false,
> >>>>> \
> >>>>
> >>>> Fwiw, for adding product options, you must go through the CSR
> process.
> >> Maybe
> >>>> there is an exception for platform specific ones?
> >>>
> >>> I didn't find any exception for platform specific options. But,
> >> "experimental" options
> >>> don't need such CSR process and, to be honest, experimental seems
> more
> >> appropriate here.
> >>> What do you think?
> >>>
> >>> Thank you for your review! :)
> >>
> >> Just a fly-by. It's up to you :) - just that product options need to be
> >> announced to the world.
> >>
> >> I kind of agree that experimental seems more appropriate. You can
> always
> >> "upgrade" it later.
> >>
> >> Thomas