From owner-freebsd-toolchain@freebsd.org  Wed Feb 24 13:19:59 2016
Return-Path: <owner-freebsd-toolchain@freebsd.org>
Delivered-To: freebsd-toolchain@mailman.ysv.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 by mailman.ysv.freebsd.org (Postfix) with ESMTP id 3EF74AB3C6F
 for <freebsd-toolchain@mailman.ysv.freebsd.org>;
 Wed, 24 Feb 2016 13:19:59 +0000 (UTC)
 (envelope-from kostikbel@gmail.com)
Received: from kib.kiev.ua (kib.kiev.ua [IPv6:2001:470:d5e7:1::1])
 (using TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits))
 (Client did not present a certificate)
 by mx1.freebsd.org (Postfix) with ESMTPS id CB3311612;
 Wed, 24 Feb 2016 13:19:58 +0000 (UTC)
 (envelope-from kostikbel@gmail.com)
Received: from tom.home (kostik@localhost [127.0.0.1])
 by kib.kiev.ua (8.15.2/8.15.2) with ESMTPS id u1ODJsBH054940
 (version=TLSv1 cipher=DHE-RSA-CAMELLIA256-SHA bits=256 verify=NO);
 Wed, 24 Feb 2016 15:19:54 +0200 (EET)
 (envelope-from kostikbel@gmail.com)
DKIM-Filter: OpenDKIM Filter v2.10.3 kib.kiev.ua u1ODJsBH054940
Received: (from kostik@localhost)
 by tom.home (8.15.2/8.15.2/Submit) id u1ODJshG054939;
 Wed, 24 Feb 2016 15:19:54 +0200 (EET)
 (envelope-from kostikbel@gmail.com)
X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com
 using -f
Date: Wed, 24 Feb 2016 15:19:54 +0200
From: Konstantin Belousov <kostikbel@gmail.com>
To: Dimitry Andric <dim@FreeBSD.org>
Cc: Raphael Kubo da Costa <rakuco@FreeBSD.org>, freebsd-toolchain@freebsd.org
Subject: Re: clang -pg, libm and the _end symbol
Message-ID: <20160224131954.GP91220@kib.kiev.ua>
References: <86povmbb7c.fsf@FreeBSD.org>
 <1CEB597F-1446-4E73-B5E2-5E5A4B3E9313@FreeBSD.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1CEB597F-1446-4E73-B5E2-5E5A4B3E9313@FreeBSD.org>
User-Agent: Mutt/1.5.24 (2015-08-30)
X-Spam-Status: No, score=-2.0 required=5.0 tests=ALL_TRUSTED,BAYES_00,
 DKIM_ADSP_CUSTOM_MED,FREEMAIL_FROM,NML_ADSP_CUSTOM_MED autolearn=no
 autolearn_force=no version=3.4.1
X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on tom.home
X-BeenThere: freebsd-toolchain@freebsd.org
X-Mailman-Version: 2.1.20
Precedence: list
List-Id: Maintenance of FreeBSD's integrated toolchain
 <freebsd-toolchain.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-toolchain>, 
 <mailto:freebsd-toolchain-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-toolchain/>
List-Post: <mailto:freebsd-toolchain@freebsd.org>
List-Help: <mailto:freebsd-toolchain-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-toolchain>, 
 <mailto:freebsd-toolchain-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 24 Feb 2016 13:19:59 -0000

On Wed, Feb 24, 2016 at 01:54:25PM +0100, Dimitry Andric wrote:
> On 24 Feb 2016, at 12:27, Raphael Kubo da Costa <rakuco@FreeBSD.org> wrote:
> > 
> > I'm reviewing an update to the textproc/miller port in bug 207194, and
> > noticed it does some ugly things in post-configure to seemingly
> > work around the following problem (on 11-HEAD at least):
> > 
> > % echo 'int main(void) { return 0; }' > foo.c
> > % clang -pg foo.c -lm
> > /usr/bin/ld: undefined reference to symbol `_end' (try adding -lc)
> > //lib/libc.so.7: could not read symbols: Bad value
> > cc: error: linker command failed with exit code 1 (use -v to see
> > invocation)
> 
> Try using: clang -pg foo.c -lm_p
> 
> That works for me (also with gcc).

It probably not quite works, in the sense that it resolves _end to
something not correctly provided by libm_p.a.  In other words, sbrk(),
if used for anything, would be broken.