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From: "ebotcazou 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 08:23:04 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102949

--- Comment #4 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
> 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:

Do you mean sparc-sun-solaris2.11 I presume?  V8 is the 32-bit architecture=
 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 vectorizati=
on
on the SPARC V9.

> 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 forc=
es
> that.  And the rev in question likely caused that to misbehave.

Possibly too low BIGGEST_ALIGNMENT in 32-bit mode?=