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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/94846] Failure to optimize jnc+inc into adc
Date: Sun, 05 Sep 2021 00:13:47 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D94846

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
After r12-897 (which added a late sink pass), we get the following in
.optimized:
  if (_10 !=3D 0)
    goto <bb 3>; [50.00%]
  else
    goto <bb 4>; [50.00%]

  <bb 3> [local count: 536870913]:
  _2 =3D _1 + 1;

  <bb 4> [local count: 1073741824]:
  # prephitmp_11 =3D PHI <_1(2), _2(3)>
  # _13 =3D PHI <_1(2), _2(3)>
  *p_5(D) =3D _13;
  return prephitmp_11;

Notice how prephitmp_11 and _13 are the same but no RTL optimizers handles
that.=