More real world matmul kernel Was: Matmul in VVM (was: Sane(r) SIMD)

From	Michael S <already5chosen@yahoo.com>
Newsgroups	comp.arch
Subject	More real world matmul kernel Was: Matmul in VVM (was: Sane(r) SIMD)
Date	2026-05-03 18:30 +0300
Organization	A noiseless patient Spider
Message-ID	<20260503183056.00003a3a@yahoo.com> (permalink)
References	(7 earlier) <2026May2.182903@mips.complang.tuwien.ac.at> <20260503112918.00001a9d@yahoo.com> <2026May3.132202@mips.complang.tuwien.ac.at> <20260503165346.00005c6b@yahoo.com> <2026May3.163954@mips.complang.tuwien.ac.at>

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On Sun, 03 May 2026 14:39:54 GMT
anton@mips.complang.tuwien.ac.at (Anton Ertl) wrote:

> Michael S <already5chosen@yahoo.com> writes:
> >In order to convince gcc to generate AVX-512 on skylake-avx512 I had
> >to go back to gcc7.  
> 
> >skylake-avx512: recognized since clang-3.9, generates semi-reasonable
> >avx512 code with clang-3.9 to 9.  
> 
> gcc-8.1 was released on May 2, 2018.
> 
> clang-10.0 was released on 24 March 2020.
> 
> Alder Lake was released in late 2021, but initially had some AVX-512
> support that was disabled via firmware later.
> 
> Given how undecisive Intel has been on Alder Lake, it seems unlikely
> that they eliminated the AVX-512 usage already in gcc-8 so early to
> avoid disappointments when Alder Lake is released.  But somehow I
> cannot come up with a different explanation.
> 
> >In this particular case it could be a blessing for Intel, because
> >newer clang code generated for znver5 used 512-bit SIMD but looks
> >horrible. I fully expect that it is slower than more conservative
> >code for Intel targets.  
> 

I wrote less artificial kernel, one that is actually very similar to how
I'd do inner loop of matmul of big matrices on SIMD512 target machine.

https://godbolt.org/z/aYhxcTehq

I am very impressed by the quality of code that gcc generated for Zen4
and Zen5. Exactly the same code would be excellent fit on any Intel
AVX512 target, but especially so on Intel processors with dual 512b
pipes.
But gcc does not generate this code for any Intel target. That's
extremely weird.

>
> The whole auto-vectorization stuff tends to be pretty unreliable
> overall.  Sometimes the code that is generated looks good, sometimes
> it is a mess, sometimes there is no auto-vectorization at all.
> 
> - anton

Very true.

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Sane(r) SIMD Thomas Koenig <tkoenig@netcologne.de> - 2026-04-26 10:26 +0000
  Re: Sane(r) SIMD BGB <cr88192@gmail.com> - 2026-04-26 12:27 -0500
    Re: Sane(r) SIMD Thomas Koenig <tkoenig@netcologne.de> - 2026-04-26 19:07 +0000
    Re: Sane(r) SIMD Stefan Monnier <monnier@iro.umontreal.ca> - 2026-04-26 18:30 -0400
      Re: Sane(r) SIMD BGB <cr88192@gmail.com> - 2026-04-27 13:58 -0500
      Re: Sane(r) SIMD MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-04-27 19:42 +0000
        Re: Sane(r) SIMD BGB <cr88192@gmail.com> - 2026-04-27 16:42 -0500
      Re: Sane(r) SIMD Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-28 05:46 +0000
  Re: Sane(r) SIMD MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-04-26 18:25 +0000
    Re: Sane(r) SIMD Thomas Koenig <tkoenig@netcologne.de> - 2026-04-26 19:38 +0000
      Re: Sane(r) SIMD MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-04-26 21:27 +0000
        Re: Sane(r) SIMD Thomas Koenig <tkoenig@netcologne.de> - 2026-04-27 05:42 +0000
          Re: Sane(r) SIMD MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-04-27 19:22 +0000
            Re: Sane(r) SIMD Thomas Koenig <tkoenig@netcologne.de> - 2026-04-27 20:22 +0000
              Re: Sane(r) SIMD BGB <cr88192@gmail.com> - 2026-04-27 17:39 -0500
              Re: Sane(r) SIMD MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-04-28 00:03 +0000
    Re: Sane(r) SIMD anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-04-27 06:56 +0000
      Re: Sane(r) SIMD Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-27 08:48 +0000
        Re: Sane(r) SIMD Michael S <already5chosen@yahoo.com> - 2026-04-27 12:23 +0300
          Re: Sane(r) SIMD Michael S <already5chosen@yahoo.com> - 2026-04-27 17:11 +0300
          Re: Sane(r) SIMD MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-04-27 19:32 +0000
            Re: Sane(r) SIMD Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-27 21:54 +0000
              Re: Sane(r) SIMD MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-04-28 00:11 +0000
                Re: Sane(r) SIMD Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-28 01:17 +0000
                Re: Sane(r) SIMD MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-04-28 18:03 +0000
            Re: Sane(r) SIMD Michael S <already5chosen@yahoo.com> - 2026-04-28 14:36 +0300
              Re: Sane(r) SIMD MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-04-28 17:45 +0000
                Re: Sane(r) SIMD Terje Mathisen <terje.mathisen@tmsw.no> - 2026-04-30 10:02 +0200
          Re: Sane(r) SIMD BGB <cr88192@gmail.com> - 2026-04-27 15:55 -0500
      Re: Sane(r) SIMD BGB <cr88192@gmail.com> - 2026-04-27 15:27 -0500
  Re: Sane(r) SIMD Terje Mathisen <terje.mathisen@tmsw.no> - 2026-04-27 18:47 +0200
    Re: Sane(r) SIMD Thomas Koenig <tkoenig@netcologne.de> - 2026-04-27 20:02 +0000
      Re: Sane(r) SIMD Terje Mathisen <terje.mathisen@tmsw.no> - 2026-04-30 14:36 +0200
        Re: Sane(r) SIMD Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-04-30 10:35 -0700
          Re: Sane(r) SIMD MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-04-30 17:51 +0000
            Re: Sane(r) SIMD scott@slp53.sl.home (Scott Lurndal) - 2026-04-30 18:16 +0000
              Re: Sane(r) SIMD MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-01 00:28 +0000
              Re: Sane(r) SIMD anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-05-01 07:48 +0000
                Re: Sane(r) SIMD Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-05-01 08:14 +0000
                Re: Sane(r) SIMD George Neuner <gneuner2@comcast.net> - 2026-05-02 00:59 -0400
        Matmul in VVM (was: Sane(r) SIMD) Thomas Koenig <tkoenig@netcologne.de> - 2026-05-01 10:21 +0000
          Re: Matmul in VVM (was: Sane(r) SIMD) MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-01 21:48 +0000
            Re: Matmul in VVM (was: Sane(r) SIMD) MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-02 02:10 +0000
              Re: Matmul in VVM (was: Sane(r) SIMD) Thomas Koenig <tkoenig@netcologne.de> - 2026-05-02 08:32 +0000
                Re: Matmul in VVM (was: Sane(r) SIMD) MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-02 18:46 +0000
                Re: Matmul in VVM (was: Sane(r) SIMD) Thomas Koenig <tkoenig@netcologne.de> - 2026-05-03 07:33 +0000
                Re: Matmul in VVM (was: Sane(r) SIMD) Michael S <already5chosen@yahoo.com> - 2026-05-03 11:13 +0300
                Re: Matmul in VVM (was: Sane(r) SIMD) MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-03 22:28 +0000
                Re: Matmul in VVM (was: Sane(r) SIMD) Thomas Koenig <tkoenig@netcologne.de> - 2026-05-10 06:55 +0000
                Re: Matmul in VVM (was: Sane(r) SIMD) MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-10 17:28 +0000
                Re: Matmul in VVM Stefan Monnier <monnier@iro.umontreal.ca> - 2026-05-10 16:15 -0400
                Re: Matmul in VVM Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-05-10 08:58 -0700
                Re: Matmul in VVM Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-05-12 02:17 +0000
                Re: Matmul in VVM Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-05-11 20:11 -0700
                Re: Matmul in VVM anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-05-12 05:14 +0000
                Re: Matmul in VVM Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-05-11 23:11 -0700
                Re: Matmul in VVM anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-05-12 07:23 +0000
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-12 18:16 +0000
                Re: Matmul in VVM anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-05-14 08:05 +0000
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-14 18:20 +0000
                Re: Matmul in VVM Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-05-13 09:09 -0700
                Re: Matmul in VVM anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-05-13 17:55 +0000
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-13 20:46 +0000
                Re: Matmul in VVM scott@slp53.sl.home (Scott Lurndal) - 2026-05-12 14:33 +0000
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-12 18:23 +0000
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-12 18:12 +0000
                Re: Matmul in VVM Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-05-12 17:08 -0700
                Re: Matmul in VVM scott@slp53.sl.home (Scott Lurndal) - 2026-05-13 14:12 +0000
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-13 17:36 +0000
                Re: Matmul in VVM Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-05-13 02:57 +0000
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-13 17:32 +0000
                Re: Matmul in VVM Terje Mathisen <terje.mathisen@tmsw.no> - 2026-05-14 09:39 +0200
                Re: Matmul in VVM Bernd Linsel <bl1-thispartdoesnotbelonghere@gmx.com> - 2026-05-13 14:02 +0200
                Re: Matmul in VVM Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-05-13 09:14 -0700
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-13 17:40 +0000
                Re: Matmul in VVM Bernd Linsel <bl1-thispartdoesnotbelonghere@gmx.com> - 2026-05-13 21:35 +0200
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-13 20:52 +0000
                Re: Matmul in VVM Bernd Linsel <bl1-thispartdoesnotbelonghere@gmx.com> - 2026-05-15 00:03 +0200
                Re: Matmul in VVM Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-05-14 16:35 -0700
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-15 00:17 +0000
                Re: Matmul in VVM Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-05-18 14:22 -0700
                Re: Matmul in VVM Bernd Linsel <bl1-thispartdoesnotbelonghere@gmx.com> - 2026-05-20 10:06 +0200
                Re: Matmul in VVM Stefan Monnier <monnier@iro.umontreal.ca> - 2026-05-14 12:19 -0400
                Re: Matmul in VVM anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-05-15 06:29 +0000
                Re: Matmul in VVM EricP <ThatWouldBeTelling@thevillage.com> - 2026-05-15 09:19 -0400
                Re: Matmul in VVM Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-05-18 14:18 -0700
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-12 18:06 +0000
                Re: Matmul in VVM Thomas Koenig <tkoenig@netcologne.de> - 2026-05-12 09:48 +0000
                Re: Matmul in VVM David Brown <david.brown@hesbynett.no> - 2026-05-12 12:59 +0200
                Re: Matmul in VVM Thomas Koenig <tkoenig@netcologne.de> - 2026-05-15 16:59 +0000
                Re: Matmul in VVM scott@slp53.sl.home (Scott Lurndal) - 2026-05-15 22:30 +0000
                Re: Matmul in VVM Thomas Koenig <tkoenig@netcologne.de> - 2026-05-16 10:22 +0000
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-16 18:09 +0000
                Re: Matmul in VVM Thomas Koenig <tkoenig@netcologne.de> - 2026-05-16 18:11 +0000
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-16 22:59 +0000
                Re: Matmul in VVM Thomas Koenig <tkoenig@netcologne.de> - 2026-05-17 07:51 +0000
                Re: Matmul in VVM scott@slp53.sl.home (Scott Lurndal) - 2026-05-17 18:51 +0000
                Re: Matmul in VVM Thomas Koenig <tkoenig@netcologne.de> - 2026-05-18 09:56 +0000
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-18 17:50 +0000
                Re: Matmul in VVM scott@slp53.sl.home (Scott Lurndal) - 2026-05-12 14:29 +0000
                Re: Matmul in VVM Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-05-25 12:00 -0700
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-25 19:36 +0000
                Re: Matmul in VVM Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-05-25 17:52 -0700
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-26 17:48 +0000
                Re: Matmul in VVM Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-05-26 11:55 -0700
                Re: Matmul in VVM Stefan Monnier <monnier@iro.umontreal.ca> - 2026-05-27 10:57 -0400
                Re: Matmul in VVM Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-05-27 11:13 -0700
                Re: Matmul in VVM Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-05-28 07:43 -0700
                Re: Matmul in VVM Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-05-28 07:53 -0700
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-28 18:08 +0000
                Re: Matmul in VVM Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-05-29 08:50 -0700
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-29 16:58 +0000
                Re: Matmul in VVM Stefan Monnier <monnier@iro.umontreal.ca> - 2026-05-28 19:29 -0400
                Re: Matmul in VVM Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-05-29 09:03 -0700
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-29 17:04 +0000
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-29 16:55 +0000
                Re: Matmul in VVM (was: Sane(r) SIMD) MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-08 18:15 +0000
                Re: Matmul in VVM (was: Sane(r) SIMD) Thomas Koenig <tkoenig@netcologne.de> - 2026-05-10 07:14 +0000
                Re: Matmul in VVM (was: Sane(r) SIMD) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-05-11 05:36 +0000
                Re: Matmul in VVM Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-05-18 11:02 -0700
                Re: Matmul in VVM MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-18 20:20 +0000
              Re: Matmul in VVM (was: Sane(r) SIMD) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-05-02 16:29 +0000
                Re: Matmul in VVM (was: Sane(r) SIMD) Michael S <already5chosen@yahoo.com> - 2026-05-03 11:29 +0300
                Re: Matmul in VVM (was: Sane(r) SIMD) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-05-03 11:22 +0000
                Re: Matmul in VVM (was: Sane(r) SIMD) Michael S <already5chosen@yahoo.com> - 2026-05-03 16:53 +0300
                Re: Matmul in VVM (was: Sane(r) SIMD) Thomas Koenig <tkoenig@netcologne.de> - 2026-05-03 14:46 +0000
                Re: Matmul in VVM (was: Sane(r) SIMD) Michael S <already5chosen@yahoo.com> - 2026-05-03 19:07 +0300
                Re: Matmul in VVM (was: Sane(r) SIMD) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-05-03 14:39 +0000
                More real world matmul kernel Was: Matmul in VVM (was: Sane(r) SIMD) Michael S <already5chosen@yahoo.com> - 2026-05-03 18:30 +0300
          Re: Matmul in VVM (was: Sane(r) SIMD) MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-01 22:21 +0000
            Re: Matmul in VVM (was: Sane(r) SIMD) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-05-02 06:02 +0000
              Re: Matmul in VVM (was: Sane(r) SIMD) MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-05-02 18:33 +0000
            Re: Matmul in VVM (was: Sane(r) SIMD) Thomas Koenig <tkoenig@netcologne.de> - 2026-05-02 06:54 +0000
              Re: Matmul in VVM (was: Sane(r) SIMD) Thomas Koenig <tkoenig@netcologne.de> - 2026-05-02 15:26 +0000

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