Re: [PATCH] likely cleanup: remove unlikely for kfree(NULL)

[Jörn Engel <joern@wohnheim.fh-wedel.de>]

On Wed, 26 April 2006 13:03:34 +0200, Arjan van de Ven wrote:
> 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 ;)

In other words, we shouldn't do this as long as most users don't have
gcc 4.1 or higher installed.  So this is somewhat pointless at the
moment.

Still, if you could respin this with gcc 4.1 and post the numbers,
Pekka, that would be quite interesting.

Jörn

-- 
The strong give up and move away, while the weak give up and stay.
-- unknown
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