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From: "tnfchris at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/113134] gcc does not version loops with early break conditions that don't have side-effects
Date: Thu, 28 Dec 2023 04:53:59 +0000 [thread overview]
Message-ID: <bug-113134-4-EpWXeqmlEI@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-113134-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113134
--- Comment #15 from Tamar Christina <tnfchris at gcc dot gnu.org> ---
(In reply to JuzheZhong from comment #14)
> > > > sure, but you can't use BIT_FIELD_REF on VLA vectors.
> > >
> > > So, for length partial vector. We can use VEC_EXTRACT with index = 0 since
> > > VEC_EXTRACT optab allows VLA vectors now for length target.
> >
> > Sounds good :)
>
> I wonder whether ARM SVE can also use this approach VEC_EXTRACT with index =
> 0.
>
> I guess the only issue is that when mask = all zero. That is, there is no
> active elements, What behavior should be here for early break ?
That shouldn't happen, in that case you wouldn't have entered the loop. To
prevent this there's always a compare of n > 0 at the start of the loops to
skip the vector body entirely.
next prev parent reply other threads:[~2023-12-28 4:53 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-25 11:29 [Bug c/113134] New: Middle end early break vectorization: Fail to vectorize a simple early break code juzhe.zhong at rivai dot ai
2023-12-25 12:35 ` [Bug c/113134] " tnfchris at gcc dot gnu.org
2023-12-27 15:21 ` [Bug c/113134] gcc does not version loops with side-effect early breaks tnfchris at gcc dot gnu.org
2023-12-28 1:21 ` [Bug c/113134] gcc does not version loops with early break conditions that don't have side-effects juzhe.zhong at rivai dot ai
2023-12-28 3:48 ` tnfchris at gcc dot gnu.org
2023-12-28 3:55 ` juzhe.zhong at rivai dot ai
2023-12-28 4:02 ` tnfchris at gcc dot gnu.org
2023-12-28 4:05 ` tnfchris at gcc dot gnu.org
2023-12-28 4:23 ` juzhe.zhong at rivai dot ai
2023-12-28 4:30 ` tnfchris at gcc dot gnu.org
2023-12-28 4:35 ` juzhe.zhong at rivai dot ai
2023-12-28 4:45 ` tnfchris at gcc dot gnu.org
2023-12-28 4:46 ` juzhe.zhong at rivai dot ai
2023-12-28 4:49 ` tnfchris at gcc dot gnu.org
2023-12-28 4:51 ` juzhe.zhong at rivai dot ai
2023-12-28 4:53 ` tnfchris at gcc dot gnu.org [this message]
2023-12-28 5:08 ` tnfchris at gcc dot gnu.org
2023-12-28 9:11 ` juzhe.zhong at rivai dot ai
2023-12-28 21:20 ` [Bug tree-optimization/113134] " pinskia at gcc dot gnu.org
2024-01-08 8:11 ` rguenth at gcc dot gnu.org
2024-01-31 11:48 ` juzhe.zhong at rivai dot ai
2024-01-31 12:04 ` rguenth at gcc dot gnu.org
2024-02-02 3:38 ` juzhe.zhong at rivai dot ai
2024-02-02 8:49 ` juzhe.zhong at rivai dot ai
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