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

Hi Evgeny,

Quentin and Matthias found it was a problem about subreg live range
update and will push a fix soon
(http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20170123/424126.html).

Thanks,
Wei.

On Fri, Jan 27, 2017 at 10:35 AM, Wei Mi <wmi at google.com>
wrote:
> Sure. Will keep you posted.
>
> Thanks,
> Wei.
>
> On Fri, Jan 27, 2017 at 10:31 AM, Evgeny Astigeevich
> <Evgeny.Astigeevich at arm.com> wrote:
>> 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
>>> >
>>> >

Quentin recommited the patch with the fix at rL293353.

Thanks,
Wei.


On Fri, Jan 27, 2017 at 1:31 PM, Wei Mi <wmi at google.com>
wrote:
> Hi Evgeny,
>
> Quentin and Matthias found it was a problem about subreg live range
> update and will push a fix soon
>
(http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20170123/424126.html).
>
> Thanks,
> Wei.
>
> On Fri, Jan 27, 2017 at 10:35 AM, Wei Mi <wmi at google.com> wrote:
>> Sure. Will keep you posted.
>>
>> Thanks,
>> Wei.
>>
>> On Fri, Jan 27, 2017 at 10:31 AM, Evgeny Astigeevich
>> <Evgeny.Astigeevich at arm.com> wrote:
>>> 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
>>>> >
>>>> >

Hi Wei,

I checked the patch. It works. The regressions are fixed. I will have results of
other benchmarks tomorrow.
Thank you very much for the quick resolution.

Kind regards,
Evgeny Astigeevich
Senior Compiler Engineer
Compilation Tools
ARM
> -----Original Message-----
> From: Wei Mi [mailto:wmi at google.com]
> Sent: Saturday, January 28, 2017 1:34 AM
> To: Evgeny Astigeevich
> Cc: llvm-dev; nd
> Subject: Re: Reversion of rL292621 caused about 7% performance
> regressions on Cortex-M
> 
> Quentin recommited the patch with the fix at rL293353.
> 
> Thanks,
> Wei.
> 
> 
> On Fri, Jan 27, 2017 at 1:31 PM, Wei Mi <wmi at google.com> wrote:
> > Hi Evgeny,
> >
> > Quentin and Matthias found it was a problem about subreg live range
> > update and will push a fix soon
> > (http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-
> 20170123/424126.html).
> >
> > Thanks,
> > Wei.