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Date: Tue, 11 Mar 2003 10:36:49 -0500
From: Daniel Jacobowitz <dan@debian.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Gerd Knorr <kraxel@bytesex.org>, "Randy.Dunlap" <rddunlap@osdl.org>,
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       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: reducing stack usage in v4l?
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On Tue, Mar 11, 2003 at 04:29:30PM +0000, Alan Cox wrote:
> On Tue, 2003-03-11 at 09:19, Gerd Knorr wrote
> 
> > That is wrong, at least the 2k memset/call mentioned by Andrew.  There
> > are lots of memset() calls, but they all are within the case switches
> > for the ioctls and zero out only the structs which are used in that code
> > path, so it is actually much smaller (~50 -> ~300 bytes maybe, depending
> > on the ioctl).
> 
> gcc sometimes does things like allocate all the objects in case
> statements at entry time. I assume its a performance win to do so.

No, it's more likely a known GCC bug to do so.  See PR middle-end/9997
if you're really curious.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer
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