From owner-freebsd-stable@FreeBSD.ORG  Mon Oct 14 20:42:33 2013
Return-Path: <owner-freebsd-stable@FreeBSD.ORG>
Delivered-To: stable@FreeBSD.org
Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115])
 (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by hub.freebsd.org (Postfix) with ESMTP id 70F2D8AC;
 Mon, 14 Oct 2013 20:42:33 +0000 (UTC)
 (envelope-from mi+thun@aldan.algebra.com)
Received: from mail1.bemta12.messagelabs.com (mail1.bemta12.messagelabs.com
 [216.82.251.3]) by mx1.freebsd.org (Postfix) with ESMTP id 28BF62651;
 Mon, 14 Oct 2013 20:42:32 +0000 (UTC)
Received: from [216.82.249.35:57186] by server-3.bemta-12.messagelabs.com id
 28/36-06818-2375C525; Mon, 14 Oct 2013 20:42:26 +0000
X-Env-Sender: mi+thun@aldan.algebra.com
X-Msg-Ref: server-2.tower-138.messagelabs.com!1381783345!2405520!1
X-Originating-IP: [209.251.202.129]
X-StarScan-Received: 
X-StarScan-Version: 6.9.12; banners=-,-,-
X-VirusChecked: Checked
Received: (qmail 13494 invoked from network); 14 Oct 2013 20:42:25 -0000
Received: from unknown (HELO PSYEXCHPMTA1.TIMEINC.COM) (209.251.202.129)
 by server-2.tower-138.messagelabs.com with SMTP; 14 Oct 2013 20:42:25 -0000
Received: by PSYEXCHPMTA1.TIMEINC.COM id hbhbj219f0g6;
 Mon, 14 Oct 2013 16:42:25 -0400 (envelope-from
 <mi+thun@aldan.algebra.com>)
Message-ID: <525C5731.7020809@aldan.algebra.com>
Date: Mon, 14 Oct 2013 16:42:25 -0400
From: "Mikhail T." <mi+thun@aldan.algebra.com>
Organization: Virtual Estates, Inc.
User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; uk;
 rv:1.9.2.14) Gecko/20110221 Lightning/1.0b2 Thunderbird/3.1.8
MIME-Version: 1.0
To: Dimitry Andric <dim@FreeBSD.org>
Subject: Re: runtime linker on 9.x/i386: clang vs. gcc
References: <525C1A5C.2030605@aldan.algebra.com>
 <B4BCF2B5-5B37-47E1-BCB7-A0159E249E10@FreeBSD.org>
In-Reply-To: <B4BCF2B5-5B37-47E1-BCB7-A0159E249E10@FreeBSD.org>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
X-Content-Filtered-By: Mailman/MimeDel 2.1.14
Cc: stable@FreeBSD.org
X-BeenThere: freebsd-stable@freebsd.org
X-Mailman-Version: 2.1.14
Precedence: list
List-Id: Production branch of FreeBSD source code <freebsd-stable.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-stable>,
 <mailto:freebsd-stable-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-stable>
List-Post: <mailto:freebsd-stable@freebsd.org>
List-Help: <mailto:freebsd-stable-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-stable>,
 <mailto:freebsd-stable-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 14 Oct 2013 20:42:33 -0000

10/14/13 4:31 PM, Dimitry Andric ???????(??):
> There is a problem when clang does tail-call optimization on i386 with
> PIC in effect, and it emits GOT relocations for the tail-called
> functions, instead of PLT relocations.  In some scenarios, such as with
> the way X.org does lazy dynamic linking, this can cause problems.  See
> alsohttp://llvm.org/PR15086  (which I unfortunately did not get much
> response on).
Ouch... That seems like a show-stopper for clang-adoption... At least, 
on i386.
> For now, a workaround is to recompile the affected .so files with
> -fno-optimize-sibling-calls (if you are optimizing).
Maybe, our clang (both src/ and ports/) should be compiled with that 
being in effect by default on i386?

    -mi