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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/107880] bool tautology missed optimisation
Date: Sat, 26 Nov 2022 18:11:12 +0000	[thread overview]
Message-ID: <bug-107880-4-sZy7C8vf49@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-107880-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107880

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=101807

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
One way of fixing this is first transform:
  _9 = ~a_4(D);
  _10 = b_3(D) | _9;
Into:

_10 = a_4(D) <= b_3(D);

And then we have:
  _8 = b_3(D) >= a_4(D);
  _7 = b_3(D) <= a_4(D);
  _1 = _7 == _8;
  _2 = b_3(D) == a_4(D);
  _6 = _1 == _2;

But  _1 is true iff a_4(D) == b_3(D) .
Let me file that second one as we don't optimize it also for int.

  parent reply	other threads:[~2022-11-26 18:11 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-26 18:03 [Bug tree-optimization/107880] New: " pinskia at gcc dot gnu.org
2022-11-26 18:06 ` [Bug tree-optimization/107880] " pinskia at gcc dot gnu.org
2022-11-26 18:11 ` pinskia at gcc dot gnu.org [this message]
2023-05-24  1:15 ` pinskia at gcc dot gnu.org
2023-08-28 20:36 ` pinskia at gcc dot gnu.org
2023-08-28 21:30 ` pinskia at gcc dot gnu.org
2023-08-28 22:52 ` pinskia at gcc dot gnu.org
2023-09-12 15:03 ` pinskia at gcc dot gnu.org

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