Re: [Lightning] Argument Management

[Paolo Bonzini]

Sandro Magi wrote:
> Under the "Argument Management" section, it states the following:
>
>   You cannot pass parameters between subroutines using the six
> general-purpose registers. This might work only when targeting
> particular architectures.
>
> Does this mean that I can't write a VM which performs interprocedural
> register allocation using GNU Lightning? Or is this statement intended
> to apply only when using the C call convention?

It's mostly because of the SPARC, which uses register windows.  If you 
don't care about it, you can pass parameters using GPR.

The way I worked around it in GNU Smalltalk was to run the whole 
interpreter in "continuation-passing style".  Which is, in fact, a 
different calling convention than the standard one.

> I'm assuming this applies only to functions which use the the standard
> jit_prolog. If I'm generating code using another calling convention
> using JIT_R/V/FPR, then the above doesn't apply, correct?

With the SPARC caveat -- no, it does not apply.

Paolo