From owner-freebsd-hackers  Thu Nov 29  5:33:35 2001
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Date: Thu, 29 Nov 2001 15:32:39 +0200
From: Peter Pentchev <roam@ringlet.net>
To: John Baldwin <jhb@FreeBSD.org>
Cc: David Xu <davidx@viasoft.com.cn>, freebsd-hackers@FreeBSD.ORG
Subject: Re: add some constraints in cpufunc.h
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	David Xu <davidx@viasoft.com.cn>, freebsd-hackers@FreeBSD.ORG
References: <00e701c17264$a4617130$ef01a8c0@davidwnt> <XFMail.011121113835.jhb@FreeBSD.org>
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In-Reply-To: <XFMail.011121113835.jhb@FreeBSD.org>; from jhb@FreeBSD.org on Wed, Nov 21, 2001 at 11:38:35AM -0800
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On Wed, Nov 21, 2001 at 11:38:35AM -0800, John Baldwin wrote:
> 
> 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.

How about PR gnu/32365?  I know next to nothing about assembler opcodes,
if "cc" would fix the PR, then the PR is a demonstration of an actual bug.

G'luck,
Peter

-- 
I am the thought you are now thinking.

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