Re: [Lightning] Argument Management

[Sandro Magi]

On Wed, Feb 20, 2008 at 11:06 AM, Paolo Bonzini <address@hidden> wrote:
>  > Perhaps an additional macro to be defined by each arch is warranted.
>  > Something like: JIT_NEEDS_PROLOG. If false, I can use a different
>  > calling convention.
>
>  There is actually jit_leaf, which would be what you need.  But it's not
>  implemented for the SPARC (it generates the same prolog) and I don't
>  have access to SPARCs anymore.

I don't think we're on the same page. I don't mean another code
generation macro, I meant a simple flag, so that my code generation
routines can switch between a custom calling convention, and the
standard prolog.

void codegen() {
  if (JIT_NEEDS_PROLOG) {
    jit_prolog(n);
    ...
  } else {
    //custom cc
    ...
  }
}

The switch will likely be #ifdef'd, but that's the idea. I don't see
how jit_leaf helps me here. It' sufficient to define:

#ifdef PPC
#define JIT_NEEDS_PROLOG 0
#elif defined(X86)
#define JIT_NEEDS_PROLOG 0
#elif defined(SPARC)
#define JIT_NEEDS_PROLOG 1
#endif

>  > I've considered CPS, particularly in conjunction with the Cheney on
>  > the MTA-style GC. Unfortunately, CPS just kills the pipeline due to
>  > the indirect function calls. Given how deep pipelines are nowadays,
>  > and the fact that they're getting deeper, I'm reluctant to go this
>  > way.
>
>  Do you have so many function calls?

I'm not sure what you mean.

Sandro