From patchwork Fri Aug 12 15:40:33 2011
Content-Type: text/plain; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
X-Patchwork-Submitter: Paolo Bonzini <bonzini@gnu.org>
X-Patchwork-Id: 109861
Return-Path: 
 <gcc-patches-return-299657-incoming=patchwork.ozlabs.org@gcc.gnu.org>
X-Original-To: incoming@patchwork.ozlabs.org
Delivered-To: patchwork-incoming@bilbo.ozlabs.org
Received: from sourceware.org (server1.sourceware.org [209.132.180.131])
	by ozlabs.org (Postfix) with SMTP id A6985B6F70
	for <incoming@patchwork.ozlabs.org>;
	Sat, 13 Aug 2011 01:41:01 +1000 (EST)
Received: (qmail 21696 invoked by alias); 12 Aug 2011 15:40:58 -0000
Received: (qmail 21688 invoked by uid 22791); 12 Aug 2011 15:40:57 -0000
X-SWARE-Spam-Status: No, hits=-2.4 required=5.0	tests=AWL, BAYES_00,
	DKIM_SIGNED, DKIM_VALID, FREEMAIL_FROM, RCVD_IN_DNSWL_LOW
X-Spam-Check-By: sourceware.org
Received: from mail-qw0-f47.google.com (HELO mail-qw0-f47.google.com)
	(209.85.216.47) by sourceware.org (qpsmtpd/0.43rc1) with
	ESMTP; Fri, 12 Aug 2011 15:40:40 +0000
Received: by qwh5 with SMTP id 5so1812742qwh.20 for
	<gcc-patches@gcc.gnu.org>; Fri, 12 Aug 2011 08:40:39 -0700 (PDT)
Received: by 10.229.78.197 with SMTP id m5mr673156qck.268.1313163639417;
	Fri, 12 Aug 2011 08:40:39 -0700 (PDT)
Received: from yakj.usersys.redhat.com (93-34-199-31.ip51.fastwebnet.it
	[93.34.199.31]) by mx.google.com with ESMTPS id
	s14sm2334839qct.30.2011.08.12.08.40.34 (version=TLSv1/SSLv3
	cipher=OTHER); Fri, 12 Aug 2011 08:40:37 -0700 (PDT)
Message-ID: <4E454971.6060509@gnu.org>
Date: Fri, 12 Aug 2011 17:40:33 +0200
From: Paolo Bonzini <bonzini@gnu.org>
User-Agent: Mozilla/5.0 (X11; Linux x86_64;
	rv:5.0) Gecko/20110707 Thunderbird/5.0
MIME-Version: 1.0
To: "H.J. Lu" <hjl.tools@gmail.com>
CC: Pedro Alves <pedro@codesourcery.com>, gcc-patches@gcc.gnu.org,
	Rainer Orth <ro@cebitec.uni-bielefeld.de>
Subject: Re: [build] Move unwinder to toplevel libgcc (v2)
References: <ydd1ux2oc1u.fsf@manam.CeBiTec.Uni-Bielefeld.DE>
	<CAMe9rOr1rL6WAcWnU6jWV5BrM+2jUudvmxRUzRrcg8qVqn5hJg@mail.gmail.com>
	<4E4519D1.7080005@gnu.org>
	<201108121338.06776.pedro@codesourcery.com>
	<CAMe9rOo2OTtisb5dAPKeO7Kaks58rJt573hEeR=wFP0HGZK8Wg@mail.gmail.com>
In-Reply-To: 
 <CAMe9rOo2OTtisb5dAPKeO7Kaks58rJt573hEeR=wFP0HGZK8Wg@mail.gmail.com>
Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-patches.gcc.gnu.org>
List-Unsubscribe: 
 <mailto:gcc-patches-unsubscribe-incoming=patchwork.ozlabs.org@gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-patches/>
List-Post: <mailto:gcc-patches@gcc.gnu.org>
List-Help: <mailto:gcc-patches-help@gcc.gnu.org>
Sender: gcc-patches-owner@gcc.gnu.org
Delivered-To: mailing list gcc-patches@gcc.gnu.org

>> Can't this sequence happen?
>>
>> proc1:       cp unwind.h $(gcc_objdir)/include/tmp-unwind.h
>> proc2:       cp unwind.h $(gcc_objdir)/include/tmp-unwind.h
>> proc1:       sh $(srcdir)/../move-if-change \
>>                $(gcc_objdir)/include/tmp-unwind.h \
>>                $(gcc_objdir)/include/unwind.h
>> proc2:       sh $(srcdir)/../move-if-change \
>>                $(gcc_objdir)/include/tmp-unwind.h \
>>                $(gcc_objdir)/include/unwind.h
>>
>> It sounds like the latter move-if-change could trip on
>> a non-extant tmp-unwind.h.
>
> Yes, we should use an unique tmp unwind.h.

Thanks, you are correct.

Paolo

2011-08-12  Paolo Bonzini  <bonzini@gnu.org>

	* Makefile.in (install-unwind_h): Create $(gcc_objdir)/include/unwind.h
	atomically.

Index: Makefile.in
===================================================================
--- Makefile.in	(revision 177688)
+++ Makefile.in	(working copy)
@@ -991,8 +1001,9 @@ gcc-extra-parts:
 all: $(extra-parts)
 
 install-unwind_h:
-	rm -f $(gcc_objdir)/include/unwind.h
-	cp unwind.h $(gcc_objdir)/include/unwind.h
-	chmod a+r $(gcc_objdir)/include/unwind.h
+	dest=$(gcc_objdir)/include/tmp$$$$-unwind.h; \
+	cp unwind.h $$dest; \
+	chmod a+r $$dest; \
+	sh $(srcdir)/../move-if-change $$dest $(gcc_objdir)/include/unwind.h
 
 all: install-unwind_h