Well I certainly didn't expect Lightning to use a JIT_R(n) register
internally. I know that those can be trashed when calling C functions, but I
assumed that they would never be trashed within the generated code.
I think that it would be better to avoid this problem, yes. JIT_R11 should
be removed from the list of available registers. It's not a big deal on MIPS
anyway, there are plenty of registers that can be used there.
Ok. For consistency with other ports, I will change it to no longer export
it. Just note that is possible to have a setup where an argument register
is also the return register. The most common case is to have JIT_R0 as
the return register, but if the jit code does not return anything, it will not
be clobbered.