X-Recipient: archive-cygwin@delorie.com X-Spam-Check-By: sourceware.org Date: Mon, 9 Jan 2012 18:36:05 +0100 From: Corinna Vinschen To: cygwin@cygwin.com Subject: Re: 16 byte pthread stack alignments Message-ID: <20120109173605.GA25130@calimero.vinschen.de> Reply-To: cygwin@cygwin.com Mail-Followup-To: cygwin@cygwin.com References: <20111221094211.GH23547@calimero.vinschen.de> <4EF1F937.9040107@gmail.com> <20111221154104.GB11841@calimero.vinschen.de> <20111221165053.GA9699@calimero.vinschen.de> <20111223135247.GM31936@calimero.vinschen.de> <20120109141345.GK15470@calimero.vinschen.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner@cygwin.com Mail-Followup-To: cygwin@cygwin.com Delivered-To: mailing list cygwin@cygwin.com On Jan 9 09:41, Brian Ford wrote: > On Mon, 9 Jan 2012, Corinna Vinschen wrote: > > > On Dec 27 18:06, Brian Ford wrote: > > > On Fri, 23 Dec 2011, Corinna Vinschen wrote: > > > > > > > Sorry, but what I don't get from your reply is if the andl worked or > > > > not. > > > > > > No; by itself, it does not. Adding a "subl $12, %%esp" following it so > > > that the stack is 16 byte aligned after the thread arg is pushed does > > > work. There are probably more efficient and/or cleaner ways of doing it > > > though. > > > > > > STC attached, but note that it seems to always pass with gcc-4. Only gcc > > > 3.4.4 appears to require the extra alignment. > > > > Ok, this is even more puzzeling. The thread function called from the > > thread_wrapper function is NOT the application thread function, but the > > Cygwin internal function thread_init_wrapper. Given that this function > > is built with the same gcc 4.x compiler as the rest of Cygwin, how on > > earth can this fail at all? Shouldn't the alignment be always correct on > > the subsequent call to the application function, given that gcc-4 is > > supposed to care? > > I'm speculating, but I believe gcc-4 only re-aligns the stack in case an > instruction in that function requires more strict alignment than the > default ABI to save overhead. Maybe. I applied that patch which also makes gcc 3 happy. Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Project Co-Leader cygwin AT cygwin DOT com Red Hat -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple