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From: "amacleod at redhat dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/108360] [13 Regression] Dead Code Elimination Regression at -Os since r13-2048-g418b71c0d535bf
Date: Tue, 10 Jan 2023 19:26:00 +0000	[thread overview]
Message-ID: <bug-108360-4-cR5WTg3wf8@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-108360-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108360

--- Comment #5 from Andrew Macleod <amacleod at redhat dot com> ---
The key change is that condition:
   _6 = f.5_5 << 4;
    e = _6;
    h_23 = (short int) _6;

    if (_21 == -1)
      goto <bb 3>; [50.00%]
    else
      goto <bb 4>; [50.00%]

On the false edge, we lose the ability to determine that h_23 is [16,16], and
instead, it remains [0,0][16,16]..    that causes us to not be able to
eliminate the branch

  parent reply	other threads:[~2023-01-10 19:26 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-10 13:10 [Bug tree-optimization/108360] New: Dead Code Elimination Regression at -Os (trunk vs. 12.2.0) yann at ywg dot ch
2023-01-10 14:48 ` [Bug tree-optimization/108360] [13 Regression] Dead Code Elimination Regression at -Os since r13-2048-g418b71c0d535bf marxin at gcc dot gnu.org
2023-01-10 17:00 ` jakub at gcc dot gnu.org
2023-01-10 17:32 ` jakub at gcc dot gnu.org
2023-01-10 17:45 ` jakub at gcc dot gnu.org
2023-01-10 19:18 ` amacleod at redhat dot com
2023-01-10 19:26 ` amacleod at redhat dot com [this message]
2023-01-10 19:28 ` amacleod at redhat dot com
2023-03-27 11:37 ` rguenth at gcc dot gnu.org
2023-04-08 14:37 ` law at gcc dot gnu.org
2023-04-26  6:57 ` [Bug tree-optimization/108360] [13/14 " rguenth at gcc dot gnu.org
2023-07-27  9:25 ` rguenth at gcc dot gnu.org
2023-08-07  8:53 ` pinskia at gcc dot gnu.org
2023-08-09  1:25 ` pinskia at gcc dot gnu.org
2024-05-21  9:13 ` [Bug tree-optimization/108360] [13/14/15 " jakub at gcc dot gnu.org

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