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From: "rguenther at suse dot de" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug fortran/102043] [9/10/11/12 Regression] Wrong array types used
 for negative stride accesses, gfortran.dg/vector_subscript_1.f90  FAILs
Date: Mon, 28 Mar 2022 06:36:44 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102043

--- Comment #36 from rguenther at suse dot de <rguenther at suse dot de> ---
On Sun, 27 Mar 2022, mikael at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102043
>=20
> --- Comment #35 from Mikael Morin <mikael at gcc dot gnu.org> ---
> A little status update.
>=20
> I have pushed the latest patch attached to this PR a little further, but =
not
> far enough to reduce the number of testsuite regressions to 0.
>=20
> I plan to submit it for gcc-13, but it won=E2=80=99t make it for gcc-12.
>=20
> (In reply to Richard Biener from comment #33)
> > With
> > a single dimension there's not much value in using ARRAY_REF over
> > pointer arithmetic and dereference.
>=20
> I have tried to fix this PR using pointer arithmetic too.
> But there are so many places in the frontend where we expect to have an a=
rray
> type when dereferencing a descriptor pointer, that it=E2=80=99s not as si=
mple as it
> seems and I finally convinced myself that the patch attached to this PR w=
as the
> best way to go.

OK.

> For gcc-12, is there a way to add a middle-end workaround using annotatio=
ns on
> descriptor types (a lang flag or something) ?

I will think of what options we have to work around this in the
middle-end (maybe with help of the frontend during gimplification).=