linux-kernel - Re: [RFC] div64

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Message-ID: <20070306160055.48b201a4@freekitty>
Date:	Tue, 6 Mar 2007 16:00:55 -0800
From:	Stephen Hemminger <shemminger@...ux-foundation.org>
To:	linux-kernel@...r.kernel.org
Subject: Re: [RFC] div64_64 support

On Wed, 7 Mar 2007 00:24:35 +0200
Sami Farin <7atbggg02@...akemail.com> wrote:

> On Tue, Mar 06, 2007 at 23:53:49 +0200, Sami Farin wrote:
> ...
> > And I found bug in gcc-4.1.2, it gave 0 for ncubic results
> > when doing 1000 loops test... gcc-4.0.3 works.
> 
> Found it.
> 
> --- cbrt-test.c~	2007-03-07 00:20:54.735248105 +0200
> +++ cbrt-test.c	2007-03-07 00:21:03.964864343 +0200
> @@ -209,7 +209,7 @@
>  
>  	__asm__("bsrl %1,%0\n\t"
>  		"cmovzl %2,%0"
> -		: "=&r" (r) : "rm" (x), "rm" (-1));
> +		: "=&r" (r) : "rm" (x), "rm" (-1) : "memory");
>  	return r+1;
>  }
>  
> Now Linux 2.6 does not have "memory" in fls, maybe it causes
> some gcc funnies some people are seeing.
> 

That code was copy-paste from:
	include/asm-x86_64/bitops.h

So shouldn't both fls() and ffs() be fixed there as well?

-- 
Stephen Hemminger <shemminger@...ux-foundation.org>
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