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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/102983] [12 Regression] Dead Code Elimination
 Regression at -O3 (trunk vs 11.2.0)
Date: Thu, 28 Oct 2021 10:31:42 +0000
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X-Bugzilla-Component: tree-optimization
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X-Bugzilla-Keywords: missed-optimization
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102983

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
           Keywords|                            |missed-optimization
   Last reconfirmed|                            |2021-10-28
     Ever confirmed|0                           |1
   Target Milestone|---                         |12.0

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Hmm:
  <bb 5> :
  if (c_3 < 0)
    goto <bb 6>; [INV]
  else
    goto <bb 9>; [INV]

  <bb 6> :
  if (c_3 !=3D 0)
    goto <bb 7>; [INV]
  else
    goto <bb 8>; [INV]


=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D BB 5 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Imports: c_3  b_4=20=20
Exports: c_3  b_4=20=20
c_3     int [-INF, 1]
b_4     int [0, 0]
    <bb 5> :
    if (c_3 < 0)
      goto <bb 6>; [INV]
    else
      goto <bb 9>; [INV]

5->6  (T) c_3 :         int [-INF, -1]
5->6  (T) b_4 :         int [0, 0]
5->9  (F) c_3 :         int [0, 1]
5->9  (F) b_4 :         int [0, 0]

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D BB 6 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Imports: c_3=20=20
Exports: c_3=20=20
c_3     int [-INF, 0]
b_4     int [0, 0]
    <bb 6> :
    if (c_3 !=3D 0)
      goto <bb 7>; [INV]
    else
      goto <bb 8>; [INV]

6->7  (T) c_3 :         int [-INF, -1]
6->8  (F) c_3 :         int [0, 0]


Hmmmm.=