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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/48580] missed optimization: integer overflow checks
Date: Wed, 09 Aug 2023 22:29:13 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D48580

--- Comment #25 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
We have this now:
  if (tmp.3_3 > 0)
    goto <bb 3>; [59.00%]
  else
    goto <bb 4>; [41.00%]

  <bb 3> [local count: 633507679]:
  _10 =3D _12 =3D=3D 0;

  <bb 4> [local count: 1073741824]:
  # iftmp.2_5 =3D PHI <_10(3), 0(2)>

I suspect what we could do is in isel change that to:
iftmp.2_5 =3D tmp.3_3 > 0 ? _12 =3D=3D 0 : 0;
(which itself gets optimized to:
iftmp.2_5 =3D (tmp.3_3 > 0) & (_12 =3D=3D 0)

Which should produce better code at least.=