Re: [PATCH] ppc: Fix 'calli' when floating-point arguments are passed

[Paul Cercueil]

[...]

> >  qemu: uncaught target signal 4 (Illegal instruction) - core dumped
>
> https://www.ibm.com/docs/en/aix/7.1?topic=set-fsqrts-floating-square-root-single-instruction
> says:
> """
> Implementation
>
> This instruction is optionally defined for PowerPC® implementations.
> Using it on an implementation that does not support this instruction
> will cause the system illegal instruction error handler to be invoked.
>
> This instruction is an optional instruction of the PowerPC®
> architecture and may not be implemented in all machines.
> """
>   Can you see what /proc/cpuinfo says? Maybe if we know it is
> not available, do a FMR, FSQRT, FRSP (extr_f_d, sqrtr_d, extr_d_f).

Ok, if I replace the FSQRTS with a simple movr_f() then I don't get an 
illegal instruction anymore, so I believe qemu-user doesn't have that 
instruction by default.

Note that it doesn't have FSQRT either.

I think we can just ignore the sqrt check then.

About the "call" check, I didn't debug it yet, but it may be related to 
calling "near" code as well. I had to use the following temporary 
workaround in my code to avoid crashes:
https://github.com/pcercuei/lightrec/blob/master/emitter.c#L35-L47

Cheers,
-Paul