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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/114009] [11/12/13/14 Regression] Missed optimization: (!a) * a => 0 when a=(a/2)*2
Date: Wed, 21 Feb 2024 00:03:12 +0000 [thread overview]
Message-ID: <bug-114009-4-54ObKsH1Mg@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-114009-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114009
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2024-02-21
Ever confirmed|0 |1
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.
What is happening is:
`(a/2)*2 == 0` gets optimized to `((unsigned)a) + 1 <= 2` and then we don't
handle:
`((unsigned)a) + 1 <= 2 ? (a/2) : 0` which is just 0. as a has the range of
[-1,1] for the truth side and divide that by 2 is always 0.
next prev parent reply other threads:[~2024-02-21 0:03 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-20 10:16 [Bug tree-optimization/114009] New: " 652023330028 at smail dot nju.edu.cn
2024-02-20 23:50 ` [Bug tree-optimization/114009] " pinskia at gcc dot gnu.org
2024-02-20 23:56 ` [Bug tree-optimization/114009] [11/12/13/14 Regression] " pinskia at gcc dot gnu.org
2024-02-21 0:03 ` pinskia at gcc dot gnu.org [this message]
2024-02-22 10:21 ` rguenth at gcc dot gnu.org
2024-03-05 13:02 ` jakub at gcc dot gnu.org
2024-03-05 14:14 ` jakub at gcc dot gnu.org
2024-03-05 14:24 ` jakub at gcc dot gnu.org
2024-03-07 7:47 ` cvs-commit at gcc dot gnu.org
2024-03-15 9:45 ` jakub at gcc dot gnu.org
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