Illegal insn due to system register

[Rakesh Kumar - Software, Noida]

> a system register. As we see, in the above insn, the source is MACL and
> destination is fr12. The insn being handled in SI mode, does not satisfy
> constraints.
> 
> Any suggestions?
 We need a GENERAL_REGS secondary reload register for that.
 Or you could also say FPUL_REGS; should be a tertiary reload
 then for whichever we left out.

I am not so familiar with reload internals. 
What exactly should be happening here?

Also I am curious to know what is the advantage of
allowing SImode for floating point registers (in the patch)?

Best Regards,
  Rakesh Kumar.