From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
 id A73BD3858405; Sun,  3 Apr 2022 19:56:25 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org A73BD3858405
From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/105123] [9/10/11/12 Regression] wrong code with -m32
 -mtune=i686 and __builtin_shuffle()
Date: Sun, 03 Apr 2022 19:56:25 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: target
X-Bugzilla-Version: 12.0
X-Bugzilla-Keywords: wrong-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: cvs-commit at gcc dot gnu.org
X-Bugzilla-Status: ASSIGNED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P2
X-Bugzilla-Assigned-To: jakub at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 9.5
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-105123-4-qQJ9bmKQfK@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-105123-4@http.gcc.gnu.org/bugzilla/>
References: <bug-105123-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-BeenThere: gcc-bugs@gcc.gnu.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Gcc-bugs mailing list <gcc-bugs.gcc.gnu.org>
List-Unsubscribe: <https://gcc.gnu.org/mailman/options/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=unsubscribe>
List-Archive: <https://gcc.gnu.org/pipermail/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-request@gcc.gnu.org?subject=help>
List-Subscribe: <https://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Sun, 03 Apr 2022 19:56:25 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D105123

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:ecc6450668326e52d019b3c298f2c61734ee32c2

commit r11-9755-gecc6450668326e52d019b3c298f2c61734ee32c2
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Sun Apr 3 21:50:43 2022 +0200

    i386: Fix up ix86_expand_vector_init_general [PR105123]

    The following testcase is miscompiled on ia32.
    The problem is that at -O0 we end up with:
      vector(4) short unsigned int _1;
      short unsigned int u.0_3;
    ...
      _1 =3D {u.0_3, u.0_3, u.0_3, u.0_3};
    statement (dead) which is wrongly expanded.
    elt is (subreg:HI (reg:SI 83 [ u.0_3 ]) 0), tmp_mode SImode,
    so after convert_mode we start with word (reg:SI 83 [ u.0_3 ]).
    The intent is to manually broadcast that value to 2 SImode parts,
    but because we pass word as target to expand_simple_binop, it will
    overwrite (reg:SI 83 [ u.0_3 ]) and we end up with 0:
       10: {r83:SI=3Dr83:SI<<0x10;clobber flags:CC;}
       11: {r83:SI=3Dr83:SI|r83:SI;clobber flags:CC;}
       12: {r83:SI=3Dr83:SI<<0x10;clobber flags:CC;}
       13: {r83:SI=3Dr83:SI|r83:SI;clobber flags:CC;}
       14: clobber r110:V4HI
       15: r110:V4HI#0=3Dr83:SI
       16: r110:V4HI#4=3Dr83:SI
    as the two ors do nothing and two shifts each by 16 left shift it all
    away.
    The following patch fixes that by using NULL_RTX target, so we expand i=
t as
       10: {r110:SI=3Dr83:SI<<0x10;clobber flags:CC;}
       11: {r111:SI=3Dr110:SI|r83:SI;clobber flags:CC;}
       12: {r112:SI=3Dr83:SI<<0x10;clobber flags:CC;}
       13: {r113:SI=3Dr112:SI|r83:SI;clobber flags:CC;}
       14: clobber r114:V4HI
       15: r114:V4HI#0=3Dr111:SI
       16: r114:V4HI#4=3Dr113:SI
    instead.

    Another possibility would be to pass NULL_RTX only when word =3D=3D elt
    and word otherwise, where word would necessarily be a pseudo from the f=
irst
    shift after passing NULL_RTX there once or pass NULL_RTX for the shift =
and
    word for ior.

    2022-04-03  Jakub Jelinek  <jakub@redhat.com>

            PR target/105123
            * config/i386/i386-expand.c (ix86_expand_vector_init_general):
Avoid
            using word as target for expand_simple_binop when doing ASHIFT =
and
            IOR.

            * gcc.target/i386/pr105123.c: New test.

    (cherry picked from commit e1a74058b784c845e84a0cf1997b54b984df483d)=