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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/108354] [13 Regression] Dead Code Elimination
 Regression at -O2 since r13-89-gb3e98eb3396e16
Date: Tue, 31 Jan 2023 04:33:44 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108354

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |pinskia at gcc dot =
gnu.org
             Status|NEW                         |ASSIGNED
         Depends on|                            |96921

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Looks like:
  _4 =3D (int) _2;
...
  i.1_15 =3D (unsigned short) _2;
  _16 =3D 1 - i.1_15;
  _6 =3D (int) _16;
...
  _8 =3D _4 | _6;



Simplify to just
  _4 =3D (int) _2;
...
_t =3D _2 ^ 1;
_6 =3D (int)_t;
...
  _8 =3D _4 | _6;

Which then simplifies down to:
_8 =3D 1; (because (_2 ^ 1) | (_2) =3D=3D 1)

Which then would be optimized.
Let me look.


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D96921
[Bug 96921] Failure to optimize combined boolean not patterns=