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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/111282] `a & (b ^ ~a)` (or `a & ~(a ^ b)`) not optimized to `a & b` in gimple
Date: Tue, 03 Oct 2023 03:12:39 +0000 [thread overview]
Message-ID: <bug-111282-4-y2AhBP92mM@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-111282-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111282
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #1)
> Note we will need to detect both `a & (b ^ ~a)` and `a & ~(a ^ b)` since a
> might be comparison too.
Well and that will handle:
```
int f0(int a, int b)
{
return (~a) & (b ^ a); // ~a & b
}
```
Which we don't currently.
on the RTL level, we currently simplify that to:
(a | b) ^ a
The interesting thing is we do simplify the above in tree via the following
pattern:
/* (X | Y) ^ X -> Y & ~ X */
next prev parent reply other threads:[~2023-10-03 3:12 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-04 6:03 [Bug tree-optimization/111282] New: " pinskia at gcc dot gnu.org
2023-09-04 6:04 ` [Bug tree-optimization/111282] " pinskia at gcc dot gnu.org
2023-09-04 6:09 ` pinskia at gcc dot gnu.org
2023-09-04 7:26 ` pinskia at gcc dot gnu.org
2023-10-03 3:12 ` pinskia at gcc dot gnu.org [this message]
2023-10-10 20:03 ` pinskia at gcc dot gnu.org
2023-10-11 0:48 ` pinskia at gcc dot gnu.org
2023-10-11 16:46 ` cvs-commit at gcc dot gnu.org
2023-10-11 16:47 ` pinskia at gcc dot gnu.org
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