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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/109845] Addition overflow/carry flag unnecessarily
 put in a temporary register
Date: Sat, 13 May 2023 18:45:59 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: middle-end
X-Bugzilla-Version: 13.1.0
X-Bugzilla-Keywords: missed-optimization
X-Bugzilla-Severity: enhancement
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109845

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2023-05-13
             Status|UNCONFIRMED                 |NEW
           Severity|normal                      |enhancement
          Component|rtl-optimization            |middle-end
           Keywords|                            |missed-optimization
     Ever confirmed|0                           |1

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So the difference between good1 and bad1 at the gimple level is the order of
operands of the bit_ior:
good1:

  ov_8 =3D _13 !=3D 0;
  _9 =3D x_2(D) !=3D 0;
  _10 =3D ov_8 | _9;
  if (_10 !=3D 0)

bad1:
  ov_7 =3D _13 !=3D 0;
  _1 =3D x_8(D) !=3D 0;
  _2 =3D _1 | ov_7;
  if (_2 !=3D 0)=