[Bug middle-end/110757] New: 7% parest regression on zen3 -Ofast -march=native -flto between g:4dbb3af1efe55174 (2023-07-14 00:54) and g:a5088dc3f5ef73c8 (2023-07-17 03:24)

[Bug middle-end/110757] New: 7% parest regression on zen3 -Ofast -march=native -flto between g:4dbb3af1efe55174 (2023-07-14 00:54) and g:a5088dc3f5ef73c8 (2023-07-17 03:24)

[hubicka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110757

            Bug ID: 110757
           Summary: 7% parest regression on zen3 -Ofast -march=native
                    -flto between g:4dbb3af1efe55174 (2023-07-14 00:54)
                    and g:a5088dc3f5ef73c8 (2023-07-17 03:24)
           Product: gcc
           Version: 13.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hubicka at gcc dot gnu.org
  Target Milestone: ---

seems there are two commits producing this regression. Run in between is
d76d19c9bc5ef113 (2023-07-16 00:16)

https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=475.457.0

There are earlier two jumps between g:52577a301ef1b86d (2023-05-30 02:20) and
g:d0c064c3eabc75cf (2023-05-31 16:46)
and between g:7ebd4a1d61993c0a (2023-04-28 07:23) and g:977a3be3ccbc7f17
(2023-05-01 13:40)

8% regression is also seen on zen1 machine:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=287.457.0

[Bug middle-end/110757] [14 Regression] 7% parest regression on zen3 -Ofast -march=native -flto between g:4dbb3af1efe55174 (2023-07-14 00:54) and g:a5088dc3f5ef73c8 (2023-07-17 03:24)

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110757

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |missed-optimization
            Summary|7% parest regression on     |[14 Regression] 7% parest
                   |zen3 -Ofast -march=native   |regression on zen3 -Ofast
                   |-flto between               |-march=native -flto between
                   |g:4dbb3af1efe55174          |g:4dbb3af1efe55174
                   |(2023-07-14 00:54) and      |(2023-07-14 00:54) and
                   |g:a5088dc3f5ef73c8          |g:a5088dc3f5ef73c8
                   |(2023-07-17 03:24)          |(2023-07-17 03:24)
   Target Milestone|---                         |14.0
                 CC|                            |pinskia at gcc dot gnu.org
            Version|13.1.0                      |14.0

[Bug middle-end/110757] [14 Regression] 7% parest regression on zen3 -Ofast -march=native -flto between g:4dbb3af1efe55174 (2023-07-14 00:54) and g:a5088dc3f5ef73c8 (2023-07-17 03:24)

[jamborm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110757

Martin Jambor <jamborm at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jamborm at gcc dot gnu.org

--- Comment #1 from Martin Jambor <jamborm at gcc dot gnu.org> ---
The first (2%) slowdown seems to be due to r14-2524-gaa6741ef2e0c31
(Turn TODO_rebuild_frequencies to a pass), I'm now bisecting the
bigger one.

[Bug middle-end/110757] [14 Regression] 7% parest regression on zen3 -Ofast -march=native -flto between g:4dbb3af1efe55174 (2023-07-14 00:54) and g:a5088dc3f5ef73c8 (2023-07-17 03:24)

[jamborm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110757

--- Comment #2 from Martin Jambor <jamborm at gcc dot gnu.org> ---
The second slow-down of 4.5% was caused by r14-2546-g061f74c06735e1:

061f74c06735e1fa35b910ae0bcf01b61a74ec23 is the first bad commit
commit 061f74c06735e1fa35b910ae0bcf01b61a74ec23
Author: Jan Hubicka <jh@suse.cz>
Date:   Sun Jul 16 23:56:59 2023 +0200

    Fix profile update in scale_profile_for_vect_loop

    When vectorizing 4 times, we sometimes do
      for
        <4x vectorized body>
      for
        <2x vectorized body>
      for
        <1x vectorized body>

    Here the second two fors handling epilogue never iterates.
    Currently vecotrizer thinks that the middle for itrates twice.
    This turns out to be scale_profile_for_vect_loop that uses
    niter_for_unrolled_loop.

[Bug middle-end/110757] [14 Regression] 7% parest regression on zen3 -Ofast -march=native -flto between g:4dbb3af1efe55174 (2023-07-14 00:54) and g:a5088dc3f5ef73c8 (2023-07-17 03:24)

[jamborm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110757

Martin Jambor <jamborm at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |lili.cui at intel dot com,
                   |                            |rguenth at gcc dot gnu.org
   Last reconfirmed|                            |2023-07-22
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1

--- Comment #3 from Martin Jambor <jamborm at gcc dot gnu.org> ---
And while I am at it, the 2.5% slowdown in April was caused by Richi's
r14-332-g24905a4bd1375c (Adjust costing of emulated vectorized
gather/scatter) and the 2.8% regression in May by 2.8% is caused by
r14-1371-ge5405f065bace0 (Handle FMA friendly in reassoc pass).

Both are small and so may not warrant their own bug-report but together
they make up almost 6% and we are now 13% slower than GCC 13 on zen 3
and 2 (on the Intel machine in LNT it is just 2.7% and I see no
regression on the Aarch64 one).

[Bug middle-end/110757] [14 Regression] 7% parest regression on zen3 -Ofast -march=native -flto between g:4dbb3af1efe55174 (2023-07-14 00:54) and g:a5088dc3f5ef73c8 (2023-07-17 03:24)

[hubicka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110757

--- Comment #4 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
Most of the profile based regression is gone between
g:1c6231c05bdccab3 (2023-07-21 03:06)
and 
g:f33fdf9e7c038639 (2023-07-23 00:17)

This should be:
commit a31ef26b056d0c4f0a9f08b6eb81456ea257298e
Author: Jan Hubicka <jh@suse.cz>
Date:   Fri Jul 21 19:38:26 2023 +0200

    Avoid scaling flat loop profiles of vectorized loops

Which "fixes" the overactive scaling of scale_profile_for_vect_loop
for static profiles.
Still not sure why propagating profile later causes regression - will take a
look.

[Bug middle-end/110757] [14 Regression] 7% parest regression on zen3 -Ofast -march=native -flto between g:4dbb3af1efe55174 (2023-07-14 00:54) and g:a5088dc3f5ef73c8 (2023-07-17 03:24)

[law at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110757

Jeffrey A. Law <law at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2
                 CC|                            |law at gcc dot gnu.org

[Bug middle-end/110757] [14/15 Regression] 7% parest regression on zen3 -Ofast -march=native -flto between g:4dbb3af1efe55174 (2023-07-14 00:54) and g:a5088dc3f5ef73c8 (2023-07-17 03:24)

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110757

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|14.0                        |14.2

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 14.1 is being released, retargeting bugs to GCC 14.2.