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 C93E4385782D; Thu, 28 Apr 2022 10:35:27 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org C93E4385782D
From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/105331] [11/12 Regression] -Wmaybe-uninitialized warning
 on va_arg with double _Complex on va_list pointer
Date: Thu, 28 Apr 2022 10:35:24 +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: 10.1.0
X-Bugzilla-Keywords: 
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: 11.4
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-105331-4-dhNKxY2xfP@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-105331-4@http.gcc.gnu.org/bugzilla/>
References: <bug-105331-4@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: Thu, 28 Apr 2022 10:35:27 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D105331

--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:89dbf9a5f55e0f7565865d1b38e681ef7d76afaf

commit r12-8301-g89dbf9a5f55e0f7565865d1b38e681ef7d76afaf
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Apr 28 12:33:59 2022 +0200

    i386: Fix up ix86_gimplify_va_arg [PR105331]

    On the following testcase we emit a bogus
    'va_arg_tmp.5' may be used uninitialized
    warning.  The reason is that when gimplifying the addr =3D &temp;
    statement, the va_arg_tmp temporary var for which we emit ADDR_EXPR
    is not TREE_ADDRESSABLE, prepare_gimple_addressable emits some extra
    code to initialize the newly addressable var from its previous value,
    but it is a new variable which hasn't been initialized yet and will
    be later, so we end up initializing it with uninitialized SSA_NAME:
      va_arg_tmp.6 =3D va_arg_tmp.5_14(D);
      addr.2_16 =3D &va_arg_tmp.6;
      _17 =3D MEM[(double *)sse_addr.4_13];
      MEM[(double * {ref-all})addr.2_16] =3D _17;
    and with -O1 we actually don't DSE it before the warning is emitted.
    If we make the temp TREE_ADDRESSABLE before the gimplification, then
    this prepare_gimple_addressable path isn't taken and we effectively
    omit the first statement above and so the bogus warning is gone.

    I went through other backends and didn't find another instance of this
    problem.

    2022-04-28  Jakub Jelinek  <jakub@redhat.com>

            PR target/105331
            * config/i386/i386.cc (ix86_gimplify_va_arg): Mark va_arg_tmp
            temporary TREE_ADDRESSABLE before trying to gimplify ADDR_EXPR
            of it.

            * gcc.dg/pr105331.c: New test.=