On Thu, 30 Nov 2006 23:49:12 +0100 Andi Kleen wrote:
> On Thursday 30 November 2006 23:32, Andrew Morton wrote:
> > On Thu, 30 Nov 2006 23:22:00 +0100
> > Andi Kleen <[EMAIL PROTECTED]> wrote:
> >
> > > >
> > > > static __inline__ int __test_and_set_bit(int nr, volatile void * addr)
> > > > {
> > > > int oldbit;
> > > >
> > > > __asm__(
> > > > "btsl %2,%1\n\tsbbl %0,%0"
> > > > :"=r" (oldbit),"+m" (ADDR)
> > > > :"dIr" (nr));
> > > > return oldbit;
> > > > }
> > > >
> > > > explodes with gcc-3.4.4.
> > >
> > > Known issue. The new form is correct and needed, but the old gcc doesn't
> > > accept
> > > it. I haven't gotten a form that is both and correct and works on the old
> > > compiler
> > > out of the gcc hackers I asked.
> >
> > Oh, thanks.
> >
> > What does "d" do, btw? My gcc info page only covers "x86" and says only
> > "`d' register"
>
> Hmm, normally edx (aka Extended D register eXtended :) or rdx
>
> But you're right it doesn't make sense here because 'd' is already included
> in 'r'.
> Probably should be dropped.
>
> >
> > (And, more importantly, where is the best description of gcc asm
> > constraints?)
>
> Either info pages or gcc source. There was also a web page somewhere with a
> tutorial,
> but i don't think it was a full reference.
e.g. (may be ix86 instead of x86_64):
http://gcc.gnu.org/onlinedocs/gcc-4.1.1/gcc/Constraints.html#Constraints
http://www-128.ibm.com/developerworks/linux/library/l-ia.html
http://www.uwsg.indiana.edu/hypermail/linux/kernel/9804.2/0953.html
---
~Randy
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