SMALL_REGISTER_CLASSES

[amylaar@cygnus.co.uk]

> You can't really deal with this using 'x' [for the audience, 'x' is
> the register class that includes only register cr0].  You might want
> to write
> 
> asm ("whatever" : "x"(clobbered));
> 
> but then you have to declare 'clobbered' as a variable, and you can't
> because there isn't a C type which can have MODE_CC :-(.

Hmmm.  Seems like a shortcoming of extended asm to me.  Maybe we should
have a fourth category of operands - scratch operands, giving a constraint
letter (list) and a mode.