From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-369587-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 29485 invoked by alias); 6 Oct 2011 14:08:29 -0000
Received: (qmail 29474 invoked by uid 22791); 6 Oct 2011 14:08:28 -0000
X-SWARE-Spam-Status: No, hits=-2.9 required=5.0	tests=ALL_TRUSTED,AWL,BAYES_00
X-Spam-Check-By: sourceware.org
Received: from localhost (HELO gcc.gnu.org) (127.0.0.1)    by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 06 Oct 2011 14:08:10 +0000
From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/50628] [4.7 Regression] gfortran.fortran-torture/execute/entry_4.f fails
Date: Thu, 06 Oct 2011 14:08:00 -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-Keywords: wrong-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rguenth at gcc dot gnu.org
X-Bugzilla-Status: NEW
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 4.7.0
X-Bugzilla-Changed-Fields:
Message-ID: <bug-50628-4-wQo5LOtSfB@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-50628-4@http.gcc.gnu.org/bugzilla/>
References: <bug-50628-4@http.gcc.gnu.org/bugzilla/>
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
Content-Type: text/plain; charset="UTF-8"
MIME-Version: 1.0
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
X-SW-Source: 2011-10/txt/msg00331.txt.bz2

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50628

--- Comment #5 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-10-06 14:08:08 UTC ---
Basically SRA transforms

union u { char c; bool b; };

u.c = ...;
if (u.c ...)

to

u.c = ...;
bool reg = u.b;
u.b = reg;
if (u.c ...)

which is at least suspicious. If a user would write this I'd say it
is simply undefined (because u.b cannot represent all values that
are in the memory location of u.c).

FRE exposes this via native_interpret_int which at the end does

  return double_int_to_tree (type, result);
}

which truncates the value to 1-bit precision.  We probably don't want
out-of-precision INTEGER_CSTs here, so we could at most fail here.
But clearly SRA should avoid doing what it does.