X-Recipient:	archive-cygwin AT delorie DOT com
X-Original-To:	cygwin AT cygwin DOT com
Delivered-To:	cygwin AT cygwin DOT com
DMARC-Filter:	OpenDMARC Filter v1.3.2 sourceware.org 8F5C5385800A
Authentication-Results:	sourceware.org;
	dmarc=none (p=none dis=none) header.from=towo.net
Authentication-Results:	sourceware.org; spf=none smtp.mailfrom=towo AT towo DOT net
Subject:	Re: [ANNOUNCEMENT] Test: {mingw64-{i686,x86_64}-,}gcc-11.1.0-0.1
To:	cygwin AT cygwin DOT com
References:	<announce DOT 871raewgfm DOT fsf AT Rainer DOT invalid>
	<f3f9f296-cde2-1549-e7e9-38c1c855d5df AT towo DOT net>
	<87mtszzsvd DOT fsf AT Rainer DOT invalid>
	<29a53ee2-cac3-6815-792d-36f96be47bd1 AT towo DOT net>
	<5d911b7f-70c6-01f5-a353-d8735be46ecd AT t-online DOT de>
From:	Thomas Wolff <towo AT towo DOT net>
Message-ID:	<04176b59-1b36-c139-76b7-046e3823caa1@towo.net>
Date:	Thu, 13 May 2021 23:57:40 +0200
User-Agent:	Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101
	Thunderbird/78.10.1
MIME-Version:	1.0
In-Reply-To:	<5d911b7f-70c6-01f5-a353-d8735be46ecd@t-online.de>
X-Provags-ID:	V03:K1:vNixXcJdaTKTUhznZoVNsPHI5IvDc1I1pxubIGLdis30CQ4a8Nb
	QEkdxTx2Z7OjLpZ/jF7bsi61nIcS6igNFY1tIeTOTY1Uk7h+WVHavArRZY6QweU9AC+H0/d
	LncvlUlSWtfC2PB6f9fIqABPIyl2AaYDjvR3JSFckhdu/ZnLUcEhQRyB3UoO6pxM0raSaIj
	4V4SDanrRMgjzxKslM5ow==
X-UI-Out-Filterresults:	notjunk:1;V03:K0:wuOL9PzVlcg=:8Xltx/ITsPotAxf6rNZCnG
	QNf3xMK8ef9wD/OQ9VehqhGn0PXnALOOfso4JcNUJQDtuNBYDYlFJcKKiva8TUtFu+QSlbxfU
	rs+zt41WmJFHtHtptJJYRwdUAzxSj5nTfl75Tq1GdjeYeHMuVegO54F+cpwOUhfaa5g9l54V1
	WiUUmgUDjknbnpzrzoA9OIXDOQaLETyIuvGZcMkdtBC4AYApIgSZSCKfYM0x3fyWV8qjgkM6m
	QjH/qgZvZFeYRtG71TIW8YFx6J3N3t8AMFddmRCBu4pFJkfJ8e2hgjmoQv9r/dZJsUY9pWPF0
	GB5TH80xRiS7pwKtUa5DFpspExUWJks12ibygQxUKeu+BW73d70BoNmxtIFBVger/KZJpDhcr
	yH4Gko6wnNE4KLhQMcnd+ZREYZCorHeVDYJD4f/Hy7HU/AM0uR2EOXVV1unH2NoB2O5lkh7SB
	7VLRyRIWL4No40DLefkAdf64UwZrdCHjo7SJCeeA2sDZE0ZUNJOwy9hIn3DOPcK+4PvTOPKKq
	atE4Sq1o2JcA+zL4rnezps=
X-Spam-Status:	No, score=-1.3 required=5.0 tests=BAYES_00, KAM_DMARC_STATUS,
	KAM_LAZY_DOMAIN_SECURITY, KAM_NUMSUBJECT, NICE_REPLY_A, RCVD_IN_DNSWL_NONE,
	RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE,
	TXREP autolearn=no autolearn_force=no version=3.4.2
X-Spam-Checker-Version:	SpamAssassin 3.4.2 (2018-09-13) on
	server2.sourceware.org
X-BeenThere:	cygwin AT cygwin DOT com
X-Mailman-Version:	2.1.29
List-Id:	General Cygwin discussions and problem reports <cygwin.cygwin.com>
List-Unsubscribe:	<https://cygwin.com/mailman/options/cygwin>,
	<mailto:cygwin-request AT cygwin DOT com?subject=unsubscribe>
List-Archive:	<https://cygwin.com/pipermail/cygwin/>
List-Post:	<mailto:cygwin AT cygwin DOT com>
List-Help:	<mailto:cygwin-request AT cygwin DOT com?subject=help>
List-Subscribe:	<https://cygwin.com/mailman/listinfo/cygwin>,
	<mailto:cygwin-request AT cygwin DOT com?subject=subscribe>
Errors-To:	cygwin-bounces AT cygwin DOT com
Sender:	"Cygwin" <cygwin-bounces AT cygwin DOT com>
X-MIME-Autoconverted:	from base64 to 8bit by delorie.com id 14DLvlXl007984

Am 13.05.2021 um 21:33 schrieb Hans-Bernhard Bröker:
> Am 13.05.2021 um 10:57 schrieb Thomas Wolff:
>
>> The crash vanishes after removing a few lines from a conditional (if 
>> block) where the condition is false.
>
> A conditions that's always false, or one that's false during the 
> execution of a particular test case?
False during execution.
>
>> This smells like wrong calculation of a relative jump (Intel "short 
>> jump") by the optimizer.
>
> If it were that simple, the problematic change should stand out like 
> the proverbial sore thumb when comparing assembly listings of the two 
> cases.  Does it? 
Not really. As the problem only occurs with -O2, I'd need to check the 
result of gcc -S -O2, but with -O2, code is stirred so much it's hardly 
recognizable. The conditional jump to skip the (dynamically false) 
conditional is even a jump backwards in this case...

-- 
Problem reports:      https://cygwin.com/problems.html
FAQ:                  https://cygwin.com/faq/
Documentation:        https://cygwin.com/docs.html
Unsubscribe info:     https://cygwin.com/ml/#unsubscribe-simple

- Raw text -