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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/27504] x && (x & y) not optimized to x & y
Date: Fri, 05 May 2023 08:17:26 +0000 [thread overview]
Message-ID: <bug-27504-4-DPpIWfwIEj@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-27504-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=27504
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #3)
> Confirmed again.
> So looking at the IR, it took until PHI-OPT4 to be able to convert it into:
> <bb 2> [local count: 1073741824]:
> if (x_3(D) != 0)
> goto <bb 3>; [50.00%]
> else
> goto <bb 4>; [50.00%]
>
> <bb 3> [local count: 536870913]:
> _1 = x_3(D) & 85;
> _5 = _1 != 0;
> _6 = (int) _5;
>
> <bb 4> [local count: 1073741824]:
> # iftmp.0_2 = PHI <_6(3), 0(2)>
In GCC 12+, phiopt2 is able to convert that into the above.
One thing that could be tried is to replace x_3 with 0 and see if _6 would
simplify down to 0 (other the phi argument). This could be part of phiopt but
would need a lot of work really.
Note VRP is able to handle the other way around already:
that is: `(x & 0x55) && x ` But that is simplier.
next prev parent reply other threads:[~2023-05-05 8:17 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-27504-4@http.gcc.gnu.org/bugzilla/>
2021-06-03 2:43 ` pinskia at gcc dot gnu.org
2023-05-05 8:17 ` pinskia at gcc dot gnu.org [this message]
2023-10-12 17:56 ` pinskia at gcc dot gnu.org
2023-10-12 18:00 ` pinskia at gcc dot gnu.org
2006-05-08 19:28 [Bug tree-optimization/27504] New: " falk at debian dot org
2006-05-09 6:20 ` [Bug tree-optimization/27504] " pinskia at gcc dot gnu dot org
2006-05-09 8:36 ` rguenth at gcc dot gnu dot org
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