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From: "rguenther at suse dot de" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/105965] [10/11/12 Regression] x86:
 single-element vectors don't have scalar FMA insns used anymore
Date: Tue, 21 Jun 2022 06:59:00 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D105965

--- Comment #6 from rguenther at suse dot de <rguenther at suse dot de> ---
On Tue, 21 Jun 2022, pinskia at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D105965
>=20
> Andrew Pinski <pinskia at gcc dot gnu.org> changed:
>=20
>            What    |Removed                     |Added
> -------------------------------------------------------------------------=
---
>           Component|target                      |tree-optimization
>            See Also|                            |https://gcc.gnu.org/bugz=
ill
>                    |                            |a/show_bug.cgi?id=3D1015=
40
>=20
> --- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
> (In reply to Richard Biener from comment #2)
> > that means we are at least missing a match.pd pattern to simplify
> >=20
> >   _1 =3D {_10};
> >   _11 =3D VIEW_CONVERT_EXPR<float>(_1);
>=20
> I had an alternative patch which I had submitted in November:
> https://gcc.gnu.org/pipermail/gcc-patches/2021-November/585597.html
>=20
> I never followed up and such. Sorry about that.

Hmm, that's actually the opposite case where we want a vector type.
But sure, when we replace _1 =3D {_10} with _1 =3D V_C_E <..> (_10); then
the V_C_E series should fold away (hopefully ;))=