From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-433427-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 6229 invoked by alias); 4 Nov 2013 11:07:52 -0000
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
Received: (qmail 4869 invoked by uid 48); 4 Nov 2013 11:05:50 -0000
From: "bernd.edlinger at hotmail dot de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/58970] [4.7/4.8/4.9 Regression] internal compiler error: in get_bit_range, at expr.c:4562
Date: Mon, 04 Nov 2013 11:07:00 -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: 4.8.2
X-Bugzilla-Keywords:
X-Bugzilla-Severity: normal
X-Bugzilla-Who: bernd.edlinger at hotmail dot de
X-Bugzilla-Status: NEW
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 4.7.4
X-Bugzilla-Flags:
X-Bugzilla-Changed-Fields:
Message-ID: <bug-58970-4-pIzhtI8mPK@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-58970-4@http.gcc.gnu.org/bugzilla/>
References: <bug-58970-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-SW-Source: 2013-11/txt/msg00204.txt.bz2

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58970

--- Comment #15 from Bernd Edlinger <bernd.edlinger at hotmail dot de> ---
(In reply to Bernd Edlinger from comment #14)
> (In reply to Jakub Jelinek from comment #13)
> > (In reply to Bernd Edlinger from comment #12)
> > > I meant the change here is not necessary, because after the
> > > if (*bitpos < 0) {...},
> > > *offset can no longer be NULL, and I'd leave the assertion untouched.
> > 
> > Sure, if *bitpos was initially negative, then *offset won't be NULL there.
> > But what I mean, are you sure that non-negative *bitpos will never be
> > smaller than bitoffset if *offset is NULL?  Of course not on this testcase...
> 
> If *bitpos is initially negative, I can proove that *offset is initially
> NULL.

However we can be sure (to assert), that if offset is initially NULL,
and *bitpos is initially >= 0, then
the bit offset of the bitfield representative must be >= 0 too.
because otherwiese, the bitfield would start at offset < 0 and end
at an offset > 0. Which is not possible.

Therefore bitoffset <= *bitpos if *bitpos is initially >= 0 and *offset is
initially == NULL. QED?