llvm dev - Jan 2017 - Reversion of rL292621 caused about 7% performance regressions on Cortex-M

Hi Wei,

Your reversion of rL292621 caused about 7% performance regressions in our
benchmark on Cortex-M7/M4.
In your commit comment I see it causes build bot failures.
What kind are the failures? Compiler crashes or incorrect code generation?  Will
you fix them?
We are interested in the changes because of performance improvements they give.

Kind regards,
Evgeny Astigeevich
Senior Compiler Engineer
Compilation Tools
ARM

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Hi Evgeny,

The failure is a compiler crash on an out-of-tree target in apple.
Quentin is helping to find a reproducible but havn't succeeded yet.
Once I get a reproducible, I will fix it. Thanks for the interest on
the work. Details about the crash can be found here:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20170123/422853.html

Thanks,
Wei.


On Fri, Jan 27, 2017 at 10:11 AM, Evgeny Astigeevich
<Evgeny.Astigeevich at arm.com> wrote:
> Hi Wei,
>
>
>
> Your reversion of rL292621 caused about 7% performance regressions in our
> benchmark on Cortex-M7/M4.
>
> In your commit comment I see it causes build bot failures.
>
> What kind are the failures? Compiler crashes or incorrect code generation?
> Will you fix them?
>
> We are interested in the changes because of performance improvements they
> give.
>
>
>
> Kind regards,
>
> Evgeny Astigeevich
>
> Senior Compiler Engineer
> Compilation Tools
> ARM
>
>

Hi Wei,

Thank you for information.
Please let me know about any progress in fixing the failures.
I can help with checking that the final patch gives the same level of
performance improvements.

Kind regards,
Evgeny Astigeevich
Senior Compiler Engineer
Compilation Tools
ARM
 
> -----Original Message-----
> From: Wei Mi [mailto:wmi at google.com]
> Sent: Friday, January 27, 2017 6:20 PM
> To: Evgeny Astigeevich
> Cc: llvm-dev; nd
> Subject: Re: Reversion of rL292621 caused about 7% performance
> regressions on Cortex-M
> 
> Hi Evgeny,
> 
> The failure is a compiler crash on an out-of-tree target in apple.
> Quentin is helping to find a reproducible but havn't succeeded yet.
> Once I get a reproducible, I will fix it. Thanks for the interest on the
work.
> Details about the crash can be found here:
> http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-
> 20170123/422853.html
> 
> Thanks,
> Wei.
> 
> 
> On Fri, Jan 27, 2017 at 10:11 AM, Evgeny Astigeevich
> <Evgeny.Astigeevich at arm.com> wrote:
> > Hi Wei,
> >
> >
> >
> > Your reversion of rL292621 caused about 7% performance regressions in
> > our benchmark on Cortex-M7/M4.
> >
> > In your commit comment I see it causes build bot failures.
> >
> > What kind are the failures? Compiler crashes or incorrect code
generation?
> > Will you fix them?
> >
> > We are interested in the changes because of performance improvements
> > they give.
> >
> >
> >
> > Kind regards,
> >
> > Evgeny Astigeevich
> >
> > Senior Compiler Engineer
> > Compilation Tools
> > ARM
> >
> >