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From: "amker at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/101145] niter analysis fails for until-wrap condition
Date: Thu, 24 Jun 2021 15:39:52 +0000	[thread overview]
Message-ID: <bug-101145-4-YImGvicmBa@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-101145-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101145

--- Comment #2 from bin cheng <amker at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #1)
> This comes up with a pending patch to split loops like
> 
> void
> foo (int *a, int *b, unsigned l, unsigned n)
> {
>   while (++l != n)
>     a[l] = b[l] + 1;
> }
> 
> into
> 
>   while (++l > n)
>     a[l] = b[l] + 1;
>   while (++l < n)
>     a[l] = b[l] + 1;
> 
> since for the second loop (the "usual" case involving no wrapping of the IV)
> this results in affine IVs and thus analyzable data dependence.

Special case like "i++ > constant" are handled in function
adjust_cond_for_loop_until_wrap, however, it only handles constant invariant on
the other side right now.

Will see how to cover simple cases as reported here.

  parent reply	other threads:[~2021-06-24 15:39 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-21  8:59 [Bug tree-optimization/101145] New: " rguenth at gcc dot gnu.org
2021-06-21  9:02 ` [Bug tree-optimization/101145] " rguenth at gcc dot gnu.org
2021-06-24 15:39 ` amker at gcc dot gnu.org [this message]
2021-06-25  1:28 ` guojiufu at gcc dot gnu.org
2021-06-25  1:34 ` amker at gcc dot gnu.org
2021-06-25 10:13 ` guojiufu at gcc dot gnu.org
2021-06-25 12:24 ` guojiufu at gcc dot gnu.org
2021-06-26  2:53 ` amker at gcc dot gnu.org
2021-07-01  3:42 ` guojiufu at gcc dot gnu.org
2021-08-25  8:39 ` cvs-commit at gcc dot gnu.org
2021-08-31 13:27 ` cvs-commit at gcc dot gnu.org
2021-09-17 10:01 ` marxin at gcc dot gnu.org
2021-12-01 19:59 ` cvs-commit at gcc dot gnu.org

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