linux-kernel - Re: [PATCH] xfs: #define out unused parameters of xfs_bmap_add_free and xfs_btree_read

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Message-Id: <200804222246.16980.vda.linux@googlemail.com>
Date:	Tue, 22 Apr 2008 22:46:16 +0200
From:	Denys Vlasenko <vda.linux@...glemail.com>
To:	Eric Sandeen <sandeen@...deen.net>
Cc:	Adrian Bunk <bunk@...sta.de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] xfs: #define out unused parameters of	xfs_bmap_add_free and xfs_btree_read_bufl

On Tuesday 22 April 2008 19:26, Eric Sandeen wrote:
> It would be a huge undertaking.
> 
> Just building xfs w/ the warning in place exposes tons of unused
> parameter warnings from outside xfs as well.

I was grepping them away.

> But, if it was deemed important enough, you could go annotate them as
> unused, I suppose, and hack away at it...  Does marking as unused just
> shut up the warning or does it let gcc do further optimizations?

It just shuts up the warning. It is still useful - suppresses
false positives.

I didn't check whether gcc is clever enough to reuse stack space
occupied by unused parameter(s) as a free space for automatic
variables. In theory it is allowed to do that and reduce stack usage
that way.
--
vda
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