[Bug tree-optimization/60165] "may be used uninitialized" warning with -O3 but not with -O2

["rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60165

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #3)
> (In reply to Vincent Lefèvre from comment #2)
> > Well, the code paths in question do not necessarily exist (you could say the
> > same thing with -O2, where the function is not inlined: there may be some
> > code paths for which fn1() doesn't initialize c).
> 
> The code path exists in the code, the fact that perhaps in your program such
> code path is never taken doesn't mean it is undesirable to warn about it.
> GCC has two kinds of warnings, the is uninitialized one where particular
> code, if executed, will always use uninitialized value, and maybe
> uninitialized, where it will use uninitialized value only conditionally. 
> That is the case here.

Where it of course still only assumes that the function is entered at all.
>From gcc-bugs-return-443443-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Thu Feb 13 09:21:40 2014
Return-Path: <gcc-bugs-return-443443-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Delivered-To: listarch-gcc-bugs@gcc.gnu.org
Received: (qmail 26489 invoked by alias); 13 Feb 2014 09:21:40 -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
Delivered-To: mailing list gcc-bugs@gcc.gnu.org
Received: (qmail 26330 invoked by uid 48); 13 Feb 2014 09:21:37 -0000
From: "joey.ye at arm dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libgcc/60166] ARM default NAN encoding violates EABI
Date: Thu, 13 Feb 2014 09:21:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: libgcc
X-Bugzilla-Version: 4.9.0
X-Bugzilla-Keywords:
X-Bugzilla-Severity: normal
X-Bugzilla-Who: joey.ye at arm dot com
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags:
X-Bugzilla-Changed-Fields:
Message-ID: <bug-60166-4-LZKpg9bWj8@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-60166-4@http.gcc.gnu.org/bugzilla/>
References: <bug-60166-4@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: 2014-02/txt/msg01200.txt.bz2
Content-length: 233

http://gcc.gnu.org/bugzilla/show_bug.cgi?id`166

--- Comment #2 from Joey Ye <joey.ye at arm dot com> ---
(In reply to Ramana Radhakrishnan from comment #1)
> Isn't this a dup of PR59833.

It isn't. This one is only impacts QNAN.