Mailing-List:	contact cygwin-developers-help AT sourceware DOT cygnus DOT com; run by ezmlm
List-Subscribe:	<mailto:cygwin-developers-subscribe AT sources DOT redhat DOT com>
List-Archive:	<http://sources.redhat.com/ml/cygwin-developers/>
List-Post:	<mailto:cygwin-developers AT sources DOT redhat DOT com>
List-Help:	<mailto:cygwin-developers-help AT sources DOT redhat DOT com>, <http://sources.redhat.com/ml/#faqs>
Sender:	cygwin-developers-owner AT sources DOT redhat DOT com
Delivered-To:	mailing list cygwin-developers AT sources DOT redhat DOT com
Date:	Tue, 23 Oct 2001 13:08:13 -0400
From:	Christopher Faylor <cgf AT redhat DOT com>
To:	cygwin-developers AT cygwin DOT com
Subject:	Re: 1.3.4 status?
Message-ID:	<20011023130813.D18754@redhat.com>
Reply-To:	cygwin-developers AT cygwin DOT com
Mail-Followup-To:	cygwin-developers AT cygwin DOT com
References:	<20011023005236 DOT 7136 DOT qmail AT lizard DOT curl DOT com> <20011022205828 DOT C18754 AT redhat DOT com> <02ea01c15b5f$7e673bc0$0200a8c0 AT lifelesswks> <20011022212759 DOT A19493 AT redhat DOT com> <032701c15b64$ea5523b0$0200a8c0 AT lifelesswks> <20011022215102 DOT A20341 AT redhat DOT com> <033101c15b66$24fc2260$0200a8c0 AT lifelesswks> <033701c15b68$f3684d70$0200a8c0 AT lifelesswks> <20011022222324 DOT B20427 AT redhat DOT com> <038601c15b70$f5ce0930$0200a8c0 AT lifelesswks>
Mime-Version:	1.0
In-Reply-To:	<038601c15b70$f5ce0930$0200a8c0@lifelesswks>
User-Agent:	Mutt/1.3.21i

On Tue, Oct 23, 2001 at 01:15:25PM +1000, Robert Collins wrote:
>----- Original Message -----
>From: "Christopher Faylor" <cgf AT redhat DOT com>
>To: <cygwin-developers AT cygwin DOT com>
>Sent: Tuesday, October 23, 2001 12:23 PM
>Subject: Re: 1.3.4 status?
>
>
>>
>> It is possible that a function would call __chkstk when it needed to
>> allocate space beyond a certain limit.  Not every function begins with
>a
>> call to __chkstk/alloca, though.
>
>objdump shows a large number of calls to __chkstk - particularly in
>functions using inline variables that are large. My 2c is that somewhere
>in gcc there is a heuristic that says "over size x variables get
>alloca'd".

Right.  gcc has to do a stack probe, causing a guard page exception (on
NT, anyway) which will cause the OS to allocate more space for the
stack.  So, to allocate beyond the current page, you have to touch each
page of the potential new space that you want to allocate.  This causes
new stack space to show up automatically.

cgf

- Raw text -