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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/100363] gcc generating wider load/store than
 warranted at -O3
Date: Fri, 30 Apr 2021 22:19:44 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D100363

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|middle-end                  |tree-optimization
           Keywords|                            |wrong-code

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
On the trunk, on aarch64:
There should be an aliasing check=20

  sfrom_289 =3D from_176 + 18446744073709551615;
  _871 =3D _843 + 18446744073709551615;
  _872 =3D _871 > 6;
  _873 =3D prephitmp_803 + 2;
  _874 =3D from_176 + 3;
  _875 =3D _873 - _874;
  _876 =3D (sizetype) _875;
  _877 =3D _876 > 12;
  _878 =3D _872 & _877;
  if (_878 !=3D 0)
    goto <bb 116>; [80.00%]
  else
    goto <bb 126>; [20.00%]


_873 is the sout


In GCC 10 branch we get something similar:
  sfrom_289 =3D from_176 + 18446744073709551615;
  _859 =3D _823 + 18446744073709551615;
  _860 =3D _859 > 8;
  _861 =3D prephitmp_783 + 2;
  _862 =3D from_176 + 3;
  _863 =3D _861 - _862;
  _864 =3D (sizetype) _863;
  _865 =3D _864 > 12;
  _866 =3D _860 & _865;
  if (_866 !=3D 0)
    goto <bb 116>; [80.00%]
  else
    goto <bb 126>; [20.00%]

But I Notice 8 vs 6 here.=