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 D9EE63842438; Wed,  9 Dec 2020 09:16:51 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org D9EE63842438
From: "rguenther at suse dot de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/98190] [11 Regression] GCC11 miscompiles code using
 _Bool when inlining: bfxil instruction misused since r11-165
Date: Wed, 09 Dec 2020 09:16:51 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: middle-end
X-Bugzilla-Version: 11.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rguenther at suse dot de
X-Bugzilla-Status: NEW
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P1
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 11.0
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-98190-4-ydeX7mRTeF@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-98190-4@http.gcc.gnu.org/bugzilla/>
References: <bug-98190-4@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: Wed, 09 Dec 2020 09:16:52 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D98190

--- Comment #11 from rguenther at suse dot de <rguenther at suse dot de> ---
On Wed, 9 Dec 2020, rsandifo at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D98190
>=20
> --- Comment #10 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu=
.org> ---
> (In reply to Jakub Jelinek from comment #9)
> > Perhaps some of those checks on the other side are redundant and could =
be
> > turned e.g. into gcc_checking_assert of gcc_assert, I bet if the MEM_REF
> > doesn't overwrite all bits, but only some subset of them, then the
> > destination couldn't be a nonmem decl and thus couldn't be promoted.
> Yeah, asserting sounds good.  Checking the other conditions makes it
> look like we could still fall through to the else for some promoted
> subregs.
>=20
> If we can't assert, I guess the rule is that we need to extend
> whenever we're storing to the MSB of the inner register.  We can
> do that either by extending the source value and the range to
> the outer register, or by assigning to the inner register and
> then extending it separately.

So I guess if you do a GIMPLE FE testcase with a __BIT_INSERT
to the MSB of a promoted var that should end up doing the extension
as well?  Like (probably doesn't parse, needs a 1-bit precision '1')

signed char __GIMPLE () foo()
{
  signed char _1;
  signed char _2;

__BB(2):
  _2 =3D __BIT_INSERT (_1(D), 1, 7);
  return _2;
}

int main()
{
  if (foo() > 0)
    abort ();
}

?=