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 932F0395BC77; Thu, 14 May 2020 17:34:49 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 932F0395BC77
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
 s=default; t=1589477689;
 bh=1vFvgUSYAe2cD3NmE3VlwlUxlups1ESEk3y+50MPLHA=;
 h=From:To:Subject:Date:In-Reply-To:References:From;
 b=Q7Uo7+gsC1cl75Bv8awj8JdKrNUcytLqxJMg3cv92GtmotA4qW01XAPXHlVTk1Auf
 LEXUlzV8A849e7qnzV0G94Rjg15tJ2qHdinvERMo/KkDLu1r60C7d5eBuuKA+cUoA3
 lI3JBiS7My88JcdWB6Jrua96pbWVO5DoqzXyLS2o=
From: "wschmidt at linux dot ibm.com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug fortran/95053] [11 regression] ICE in f951: gfc_divide()
Date: Thu, 14 May 2020 17:34:49 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: fortran
X-Bugzilla-Version: 11.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: wschmidt at linux dot ibm.com
X-Bugzilla-Status: WAITING
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: anlauf at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 11.0
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-95053-4-znmjMw4JjB@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-95053-4@http.gcc.gnu.org/bugzilla/>
References: <bug-95053-4@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: <http://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: <http://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Thu, 14 May 2020 17:34:49 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95053

--- Comment #24 from wschmidt at linux dot ibm.com ---
On 5/14/20 12:08 PM, sgk at troutmask dot apl.washington.edu wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95053
>
> --- Comment #23 from Steve Kargl <sgk at troutmask dot apl.washington.edu=
> ---
> On Thu, May 14, 2020 at 02:57:37PM +0000, wschmidt at gcc dot gnu.org wro=
te:
>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95053
>>
>> Bill Schmidt <wschmidt at gcc dot gnu.org> changed:
>>
>>             What    |Removed                     |Added
>> ------------------------------------------------------------------------=
----
>>                   CC|                            |wschmidt at gcc dot gn=
u.org
>>
>> --- Comment #22 from Bill Schmidt <wschmidt at gcc dot gnu.org> ---
>> Breaking legitimate code, even if "borderline," does not seem right to m=
e.
>> Zero division is generally a runtime exception because of such cases.
>>
>> You write code for a general case, then later you discover "oh, well, we=
 could
>> make this variable zero for our specific usage," and now the compiler th=
rows a
>> fit?  Seems like this is warning-level stuff.
>>
> If Bill's reduction of the several thousand-line file to 10ish
> lines is an accurate reduction (and I have no reasons to doubt
> that it isn't), then no.  It is an programming error.  This is
> not the first time that gfortran has found a programming error
> in WRF.  Sure, in this case the 'if (cdleps > 0)' leads to dead
> code elimination, but DCE happens after gfortran has done some
> constant folding and common subexpression elimination in the
> front-end.
>
I'm afraid I disagree.=C2=A0 A divide-by-zero that cannot ever be executed =
is=20
not an error.=