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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/112787] Codegen regression of large GCC vector
 extensions when enabling SVE
Date: Mon, 18 Mar 2024 23:11:39 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D112787

--- Comment #9 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #8)
> (In reply to Eric Botcazou from comment #7)
> > This has introduced regressions on the 12 and 13 branches for x86-64/Li=
nux:
> >=20
> > FAIL: g++.dg/opt/pr91838.C  -std=3Dc++14  scan-assembler
> > pxor\\\\s+%xmm0,\\\\s+%xmm0
> > FAIL: g++.dg/opt/pr91838.C  -std=3Dc++17  scan-assembler
> > pxor\\\\s+%xmm0,\\\\s+%xmm0
> > FAIL: g++.dg/opt/pr91838.C  -std=3Dc++20  scan-assembler
> > pxor\\\\s+%xmm0,\\\\s+%xmm0
> >=20
> > https://gcc.gnu.org/pipermail/gcc-testresults/2024-March/809244.html
>=20
> The IR looks like:
>   _4 =3D BIT_FIELD_REF <x_1(D), 16, 0>;
>   _5 =3D _4 >> 8;
>=20
> Well that is "undefined" in the IR.
> That requires r14-2821-gd1c072a1c3411a6fe29900750b38210af8451eeb and
> r14-2985-g04aa0edcace22a to be backported too.
> I guess this testcase should just be xfailed on the GCC 13 and 12 branches
> even.

Also note bug 91838 comment #17 specifically talks about this could happen
even.=