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Date: Wed, 21 Nov 2001 11:38:35 -0800 (PST)
From: John Baldwin <jhb@FreeBSD.org>
To: David Xu <davidx@viasoft.com.cn>
Subject: RE: add some constraints in cpufunc.h
Cc: freebsd-hackers@FreeBSD.ORG
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On 21-Nov-01 David Xu wrote:
> 4.4-stable, file sys/i386/include/cpufunc.h, 
> 
> --- cpufunc.h.orig      Wed Nov 21 13:35:36 2001
> +++ cpufunc.h   Wed Nov 21 15:00:12 2001
> @@ -72,7 +72,7 @@
>  {
>         u_int   result;
>  
> -       __asm __volatile("bsfl %0,%0" : "=r" (result) : "0" (mask));
> +       __asm __volatile("bsfl %0,%0" : "=r" (result) : "0" (mask) : "cc");
>         return (result);
>  }
>  
> @@ -81,7 +81,7 @@
>  {
>         u_int   result;
>  
> -       __asm __volatile("bsrl %0,%0" : "=r" (result) : "0" (mask));
> +       __asm __volatile("bsrl %0,%0" : "=r" (result) : "0" (mask) : "cc");
>         return (result);
>  }
>  
> @@ -305,7 +305,7 @@
>         u_int   result;
>  
>         __asm __volatile("xorl %0,%0; xchgl %1,%0"
> -                        : "=&r" (result) : "m" (*addr));
> +                        : "=&r" (result) : "m" (*addr) : "cc");
>         return (result);
>  }
> 

Have you had actual bugs as a result of "cc" not being in the constraints?

If so, there's a _lot_ more places that need this.  All the atomic ops, for
example.

-- 

John Baldwin <jhb@FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

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