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To: linux-kernel@vger.kernel.org
From: "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [patch] [sched] bitmap cleanup, speedup, 2.5.3-pre5
Date: 28 Jan 2002 07:46:19 -0800
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Followup to:  <Pine.LNX.4.33.0201281744070.9796-100000@localhost.localdomain>
By author:    Ingo Molnar <mingo@elte.hu>
In newsgroup: linux.dev.kernel
> 
> +static __inline__ unsigned long __ffs(unsigned long word)
> +{
> +	__asm__("bsfl %1,%0"
> +		:"=r" (word)
> +		:"r" (word));
>  	return word;
>  }
> 

Should typically be:

static __inline__ unsigned long __ffs(unsigned long word)
{
	__asm__("bsfl %1,%0"
		:"=r" (word)
		:"rm" (word));
 	return word;
 }

There is no reason to force the compiler to put the operand in a
register.

	-hpa
-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
http://www.zytor.com/~hpa/puzzle.txt	<amsp@zytor.com>