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From: "hubicka at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/110649] [14 Regression] 25% sphinx3 spec2006 regression
 on Ice Lake and zen between g:acaa441a98bebc52 (2023-07-06 11:36) and
 g:55900189ab517906 (2023-07-07 00:23)
Date: Fri, 14 Jul 2023 14:39:31 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D110649

Jan Hubicka <hubicka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=3D10647
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2023-07-14
             Status|UNCONFIRMED                 |NEW

--- Comment #3 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
Thanks for bisecting this! We also have PR10647 which is tracked to this
change.
The change correct loop profile after header copying:

test()
{
        for (int i =3D 0; i < 10; i++)
                test2();
}

has probability of exit conditional 90.9% before loop header copying (since=
 it
technically iterates 10 times) while after loop header copying and optimizi=
ng
out the constant "if (0<10)" test it has only 90% loopback probability.

So probably fixing the bug above triggers something else.
I will first look at PR10647 and see if I can figure out what is going on
there.=