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Re: [PATCH][Aarch64] Fix vec_perm cost for thunderx2t99

On 05.11.2019 15:09, Kyrylo Tkachov wrote:

On 11/5/19 11:54 AM, Anton Youdkevitch wrote:

On 05.11.2019 14:43, Kyrylo Tkachov wrote:
> Hi Andrew, Anton,
> > On 11/1/19 11:22 PM, Andrew Pinski wrote:
>> On Fri, Nov 1, 2019 at 7:03 AM Anton Youdkevitch
>> <> wrote:
>>> Hello,
>>> Here is the one-liner that fixes the incorrect
>>> vec_perm cost for thunderx2t99 chip.
>>> With the patch applied 526.blender of CPU2017
>>> gets ~5% improvement with no measurable changes
>>> for other benchmarks.
>>> Bootstrapped OK on aarch64-linux-gnu.
>>> OK for trunk?
>> Maybe the big question is vec_perm used for both 1 input and 2 input
>> cases?  If so maybe splitting the two cases would be important too.
>> Otherwise this is ok from my point of view but I can't approve it.
> I'd be interested to see a testcase/demonstration where this would would
> be beneficial.
Well, since I measured this on SPEC 2017, so, the result is
the overall benchmark score. I can try to extract the relevant
pieces of code that get compiled differently to see if they can
be make into a standalone testcase. I didn't try this yet, though.

Sorry, I was referring to Andrew's suggestion about splitting the costs rather than your change.

> > In the meantime this patch is ok if it helps thunderx2t99 performance. > > 2019-11-01 Anton Youdkevitch <> > >           * gcc/config/aarch64/aarch64.c (thunderx2t99_vector_cost):
>           change vec_perm field
> > ChangeLog nits: > > * Two spaces between name and date+email > > * No gcc/ prefix as the relevant ChangeLog file lives in gcc/ > > * End entry with full stop.
Thanks, will do like this next time.

> > Anton, do you need someone to commit this for you?
Yes, it would be nice if you can do this for me.

Committed as r277826 with the following adjusted ChangeLog:

2019-11-05  Anton Youdkevitch <>

     * config/aarch64/aarch64.c (thunderx2t99_vector_cost):
     Change vec_perm field to 10.

Thanks for the patch. If you intend to make more contributions in the future it would be worth sorting a copyright assignment if you haven't done so already.
Thanks a lot for pushing it.
I will figure that out.


> > Thanks, > > Kyrill > > > >>
>> Thanks,
>> Andrew Pinski
>>> 2019-11-01 Anton Youdkevitch <>
>>>           * gcc/config/aarch64/aarch64.c (thunderx2t99_vector_cost):
>>>           change vec_perm field
>>> --
>>>     Thanks,
>>>     Anton

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