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Subject: Re: [PATCH] likely cleanup: remove unlikely for kfree(NULL)
From: Arjan van de Ven <arjan@infradead.org>
To: Pekka J Enberg <penberg@cs.Helsinki.FI>
Cc: =?ISO-8859-1?Q?J=F6rn?= Engel <joern@wohnheim.fh-wedel.de>,
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Date: Wed, 26 Apr 2006 13:03:34 +0200
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On Wed, 2006-04-26 at 13:57 +0300, Pekka J Enberg wrote:
> On Wed, 26 April 2006 10:27:18 +0200, Arjan van de Ven wrote:
> > > > what I would like is kfree to become an inline wrapper that does the
> > > > null check inline, that way gcc can optimize it out (and it will in 4.1
> > > > with the VRP pass) if gcc can prove it's not NULL.
> 
> On Wed, 2006-04-26 at 12:05 +0200, Jörn Engel wrote:
> > > How well can gcc optimize this case? 
> 
> On Wed, 26 Apr 2006, Arjan van de Ven wrote:
> > if you deref'd the pointer it'll optimize it away (assuming a new enough
> > gcc, like 4.1)
> 
> Here are the numbers for allyesconfig on my setup.
> 
> 				Pekka
> 
> gcc version 3.4.5 (Gentoo 3.4.5-r1, ssp-3.4.5-1.0, pie-8.7.9)


this is an ancient gcc without VRP so yeah the growth is expected ;)