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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/101842] Vectorizer doesn't vectorize when loop bound depends on two independent variables that are unknown
Date: Tue, 10 Aug 2021 10:54:21 +0000 [thread overview]
Message-ID: <bug-101842-4-MzrMbn5Ffj@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-101842-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101842
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Tamar Christina from comment #3)
> (In reply to Richard Biener from comment #2)
> > OK, so with a hack like the following we vectorize the BB as
> >
> > vect__1.10_62 = MEM <vector(4) float> [(float *)p_34];
> > vect_powmult_9.11_61 = vect__1.10_62 * vect__1.10_62;
> > _60 = .REDUC_PLUS (vect_powmult_9.11_61);
> > d_25 = d_35 - _60;
> > p_26 = p_34 + 16;
> > i_27 = i_37 + 4;
> > _10 = len_20(D) > i_27;
> > _11 = lim_21(D) <= d_25;
> > _12 = _10 & _11;
> > if (_12 != 0)
> >
>
> Ah awesome!
>
> >
> > the hack simply re-starts reduction discovery at the "previous" stmt
> > (this breaks down after skipping the first stmt eventually). As said,
> > it's a hack. But is that the kind of vectorization you expect?
>
> Yeah that looks perfect, the patch seems to be based on a different code
> than upstream so couldn't apply it to test the full loop, but this looks
> perfect! (We already vectorize a similar loop without the `&& d >= lim`
> condition).
It's applied to my working tree so that's possible. Note it doesn't
vectorize the loop but the loop body in basic-block vectorization.
next prev parent reply other threads:[~2021-08-10 10:54 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-10 9:41 [Bug tree-optimization/101842] New: " tnfchris at gcc dot gnu.org
2021-08-10 10:06 ` [Bug tree-optimization/101842] " rguenth at gcc dot gnu.org
2021-08-10 10:22 ` rguenth at gcc dot gnu.org
2021-08-10 10:44 ` tnfchris at gcc dot gnu.org
2021-08-10 10:54 ` rguenth at gcc dot gnu.org [this message]
2021-08-10 11:16 ` tnfchris at gcc dot gnu.org
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