Re: iconv make check failures under ppc

[Franz Sirl <Franz dot Sirl-kernel at lauterbach dot com>]

On Sat, 09 Sep 2000, Geoff Keating wrote:
> > Date: Sat, 09 Sep 2000 14:08:26 -0400
> > From: "Kevin B. Hendricks" <kevin.hendricks@sympatico.ca>
> > Reply-To: khendricks@ivey.uwo.ca
> >
> > -#define PPC_DCBST(where) asm volatile ("dcbst 0,%0" : : "r"(where) :
> > "memory") -#define PPC_SYNC asm volatile ("sync" : : : "memory")
> > +#define PPC_DCBST(where) asm ("dcbst 0,%0" : : "r"(where) : "memory")
> > +#define PPC_SYNC asm ("sync" : : : "memory")
> >  #define PPC_ISYNC asm volatile ("sync; isync" : : : "memory")
> > -#define PPC_ICBI(where) asm volatile ("icbi 0,%0" : : "r"(where) :
> > "memory") +#define PPC_ICBI(where) asm ("icbi 0,%0" : : "r"(where) :
> > "memory") #define PPC_DIE asm volatile ("tweq 0,0")
>
> These changes have no effect.  All 'asm' statements with no outputs
> are automatically considered 'volatile'.  Any problems you are seeing
> are most likely compiler bugs.

This isn't excactly clear from the documentation, at least if I take the 
smallest common denominator (worst possible interpretation :-) ):

   An `asm' instruction without any operands or clobbers (and "old
 style" `asm') will not be deleted or moved significantly, regardless,
 unless it is unreachable, the same wasy as if you had written a
 `volatile' keyword.

Since we have "memory" clobbers on all this instructions, does this mean it 
counts as an output? Or do we have 3 levels of  volatile behaviour? Like
 - no volatile with outputs
 - no volatile with no outputs (and no clobbers?)
 - volatile written or oldstyle asm
?

Anyway, the documentation clearly states that the explicit use of volatile is 
the recommended practice, so I think we better change it.

Franz.