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From: "linkw at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/98138] BB vect fail to SLP one case
Date: Wed, 06 Jan 2021 03:29:46 +0000 [thread overview]
Message-ID: <bug-98138-4-jgjahASTnP@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-98138-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98138
--- Comment #5 from Kewen Lin <linkw at gcc dot gnu.org> ---
(In reply to Kewen Lin from comment #4)
> One rough idea seems:
> 1) Relax this condition all_uniform_p somehow to get SLP instance building
> to go deeper and get those p1/p2 loads as SLP nodes.
> 2) Introduce one more vect_pattern recognizer to catch this kind of
> pattern, transform the slp instance as we expect. I assume we can know the
> whole slp instance then we can transform it as we want here. Probably need
> some costing condition to gate this pattern matching.
> 3) If 2) fail, trim the slp instance from those nodes which satisfy
> all_uniform_p condition to ensure it's same as before.
>
For 2), instead of vect_pattern with IFN, the appropriate place seems to be
vect_optimize_slp.
But after more thinking, building SLP instance starting from group loads
instead of group stores looks more straightforward.
a0 = (p1[0] - p2[0]);
a1 = (p1[1] - p2[1]);
a2 = (p1[2] - p2[2]);
a3 = (p1[3] - p2[3]);
Building the vector <a0, a1, a2, a3> looks more natural and then check the uses
of its all lanes and special patterns to have vector <t0, t1, t2, t3> and
repeat similarly.
Hi Richi,
Is this a good example to request SLP instance build starting group loads?
next prev parent reply other threads:[~2021-01-06 3:29 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-04 10:46 [Bug tree-optimization/98138] New: " linkw at gcc dot gnu.org
2020-12-04 10:52 ` [Bug tree-optimization/98138] " linkw at gcc dot gnu.org
2020-12-04 12:19 ` rguenth at gcc dot gnu.org
2020-12-07 3:10 ` linkw at gcc dot gnu.org
2021-01-05 8:42 ` linkw at gcc dot gnu.org
2021-01-06 3:29 ` linkw at gcc dot gnu.org [this message]
2021-01-06 9:48 ` rguenth at gcc dot gnu.org
2021-01-12 7:23 ` linkw at gcc dot gnu.org
2021-01-12 7:25 ` linkw at gcc dot gnu.org
2021-08-04 10:31 ` rguenth at gcc dot gnu.org
2022-07-06 10:39 ` ktkachov at gcc dot gnu.org
2023-02-01 8:19 ` manolis.tsamis at vrull dot eu
2023-10-04 22:37 ` jiangning.liu at amperecomputing dot com
2023-10-05 6:58 ` rguenth at gcc dot gnu.org
2023-10-09 7:38 ` rguenth at gcc dot gnu.org
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