Re: [Lightning] Code patching, context switching

[Paolo Bonzini]

> >  Yes.  On the PowerPC, the argument registers are *not* available to the
> >  user, because they are caller-save while GNU lightning always provides
> >  the illusion that they are callee-save.
>
> I don't get it. Are you saying that the PPC's entire register file is
> not accessible via JIT_R, JIT_V and JIT_FPR?

Yes.  r3-r9, which the ABI uses for argument passing, are not accessible 
at all.  In the prolog, they are moved to other, callee-save registers, 
which are also not accessible with JIT_{R,V} but only with jit_getarg.

> I'm wary of setjmp though, because I've inspected the Windows setjmp.h
> header, and it doesn't seem to save the floating point registers on
> x86. Anyway, it sounds like you're implying this is a Lightning
> limitation, so any clarification is much appreciated. :-)

Yes, it is.

Paolo