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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/110992] [13/14 Regression] missed VRP optimization due to transformation of `a & -zero_one_valued_p` into `a * zero_one_valued_p`
Date: Fri, 15 Sep 2023 03:19:01 +0000	[thread overview]
Message-ID: <bug-110992-4-8xzMIgzQJp@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-110992-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110992

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|14.0                        |13.3
            Summary|[14 Regression] Dead Code   |[13/14 Regression] missed
                   |Elimination Regression at   |VRP optimization due to
                   |-O3 since                   |transformation of `a &
                   |r14-1654-g7ceed7e3e29       |-zero_one_valued_p` into `a
                   |                            |* zero_one_valued_p`

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Hmm, I think this is a ranger issue really.
Take:
```
int f(unsigned b, short c)
{
  int bt = b;
  int bt1 = bt;
  int t = bt1 & -(c!=0);
 // int t = bt1 * (c!=0);

  if (!t) return 0;
  foo(bt == 0);
  return 0;
}
```

That `bt == 0` should be figured out that is 0 there. We could figure that out
in GCC 12 even. But in GCC 13+ we could not.

That is traced back to r13-793-g8fb94fc6097c but really the ranger should
figure out if you have a*b != 0, then both a and b should be non-zero ...
But currently that is not support ....
It looks like we only handle `a & b` that way ...

  parent reply	other threads:[~2023-09-15  3:19 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-11 13:24 [Bug tree-optimization/110992] New: [14 Regression] Dead Code Elimination Regression at -O3 since r14-1654-g7ceed7e3e29 scherrer.sv at gmail dot com
2023-08-11 17:38 ` [Bug tree-optimization/110992] " pinskia at gcc dot gnu.org
2023-08-26  0:30 ` pinskia at gcc dot gnu.org
2023-09-14 21:11 ` pinskia at gcc dot gnu.org
2023-09-14 21:22 ` pinskia at gcc dot gnu.org
2023-09-15  3:19 ` pinskia at gcc dot gnu.org [this message]
2023-09-15  3:54 ` [Bug tree-optimization/110992] [13/14 Regression] missed VRP optimization due to transformation of `a & -zero_one_valued_p` into `a * zero_one_valued_p` pinskia at gcc dot gnu.org
2023-09-15  4:13 ` pinskia at gcc dot gnu.org
2023-09-15  4:33 ` pinskia at gcc dot gnu.org
2023-09-15 16:28 ` pinskia at gcc dot gnu.org
2023-09-15 22:45 ` pinskia at gcc dot gnu.org
2023-09-16 16:33 ` pinskia at gcc dot gnu.org
2023-09-18 23:51 ` pinskia at gcc dot gnu.org
2024-03-07 23:24 ` law at gcc dot gnu.org
2024-03-09  6:40 ` law at gcc dot gnu.org
2024-03-09  8:55 ` xry111 at gcc dot gnu.org
2024-05-21  9:16 ` [Bug tree-optimization/110992] [13/14/15 " jakub at gcc dot gnu.org

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