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From: "rguenther at suse dot de" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/103116] SLP vectoriser fails to peel for gaps
Date: Wed, 04 May 2022 13:06:21 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103116

--- Comment #6 from rguenther at suse dot de <rguenther at suse dot de> ---
On Wed, 4 May 2022, rsandifo at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103116
>=20
> --- Comment #5 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.=
org> ---
> (In reply to Richard Biener from comment #3)
> > We could make peeling for gaps handle this by making it not a flag but
> > indicate the number of vector(!?) iterations we need to peel.
> I think it'd be better to keep it in scalar iterations if possible.
> For example, we still need to peel for gaps when using masked LD2s
> if only the first vector result is needed.  But we do only need to
> peel 1 scalar iteration, rather than a whole vector's worth.
>=20
> But yeah, agree that moving from 0-or-1 to a general number sounds good.

Yep.  I'll keep that for GCC 13, the posted fix should be what we can
reasonably easy backport.=