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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/102949] [12 regression]
 gcc.dg/vect/slp-reduc-1.c FAIL
Date: Thu, 28 Oct 2021 08:25:01 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102949

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Eric Botcazou from comment #4)
> > Hm, I tried --target=3Dsparcv8-sun-solaris2.11 but that seems to fail to
> > reproduce any vectorization with -O2 -ftree-vectorize.  If I add -mvis =
I get
> > something that could resemble the code you quote:
>=20
> Do you mean sparc-sun-solaris2.11 I presume?  V8 is the 32-bit architectu=
re
> of the 90's, everything is V9 nowadays (but sparcv9-*-* is the 64-bit
> compiler).
> But yes, in any case, -mvis is indeed always required to enable
> vectorization on the SPARC V9.
>=20
> > But somehow we end up with:
> >=20
> >         .section        ".data"
> >         .align 4
> >         .type   uc, #object
> >         .size   uc, 64
> > uc:
> >         .long   0
> >         .long   1
> >         .long   2
> >         .long   3
> >=20
> > so 'uc' is not properly aligned even though the vectorizer thinks it fo=
rces
> > that.  And the rev in question likely caused that to misbehave.
>=20
> Possibly too low BIGGEST_ALIGNMENT in 32-bit mode?

For the default to work, yes - but I'm testing a patch fixing the vectorizer
which attemts to override DECL_ALIGN but fails because of a mistake in
the mentioned revision.=