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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/100864] New: (a&!b) | b is not opimized to a
 | b for conditionals
Date: Tue, 01 Jun 2021 23:48:33 +0000
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X-Bugzilla-Component: tree-optimization
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D100864

            Bug ID: 100864
           Summary: (a&!b) | b is not opimized to a | b for conditionals
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---

Take:
_Bool f(int a, int b, _Bool e)
{
  _Bool c =3D (a > b);
  _Bool d =3D !c;
  return (e & d) | c;
}
--- CUT ----
We get currently:
  c_5 =3D a_3(D) > b_4(D);
  _2 =3D a_3(D) <=3D b_4(D);
  _1 =3D _2 & e_7(D);
  _6 =3D _1 | c_5;

But this should be optimized to just:

c_5 =3D a_3(D) <=3D b_4(D);
_6 =3D e_7(D) | c_5;

I noticed this while fixing PR 96923.=