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From: "xry111 at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/109493] Broken O2 optimization on s390x in GCC 13
Date: Thu, 13 Apr 2023 08:37:00 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109493

Xi Ruoyao <xry111 at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |xry111 at gcc dot gnu.org

--- Comment #7 from Xi Ruoyao <xry111 at gcc dot gnu.org> ---
(In reply to Mikhail Mitskevich from comment #4)
> (In reply to Andrew Pinski from comment #1)
> >  belt_mac_st* st =3D &state;
> >  belt_mac_st* st2 =3D &state2;
> >  ((word*)(st->s))[0] =3D 0, ((word*)(st->s))[1] =3D 0;
> >  ((word*)(st->r))[0] =3D 0, ((word*)(st->r))[1] =3D 0;
> >  st->filled =3D 0;
> >=20
> > I am 99% sure those are aliasing rule violations.
> >=20
> > Does -fno-strict-aliasing help?
>=20
> With -fno-strict-aliasing option code works as well as with -O1 option.

Then it's likely the code is buggy, not GCC is buggy (unless you have some
fancy type attributes on "word" or "belt_mac_st").=