Re: Compilation to native

[Matthew Mundell <matt@mundell.ukfsn.org>]

(nobody) writes:

> Miles Bader <miles@gnu.org> writes:
>
> > On Tue, Apr 13, 2004 at 01:32:37PM -0400, Stefan Monnier wrote:
> > > You mean you added two byteops: one to read the Nth word on the stack
> > > (counting from the top) and the other to set that word?  I expect you
> > > called them something like `sset' and `sref'?
> > > Sounds generally useful (something similar is used in the `lexical' branch
> > > of Miles, you might want to check that out).
> >
> > Yes; here are the new  byte codes in the lexical-binding branch:
> >
> >    #define Bstack_ref 0
> >    #define Bstack_set  0262
> >    #define Bstack_set2 0263
> >    #define Bvec_ref    0264
> >    #define Bvec_set    0265
> >    #define BdiscardN   0266
> >
> > stack_ref is a `1 byte with embedded constant' opcode; stack_set2 uses a
> > following 2-byte constant,
> > the rest use a following 1-byte constant (as they
> > have lisp-level equivalents, unusually large offsets can be handled by
> > calling an out-of-line function).  discardN uses a hack that allows the TOS
> > to optionally be preserved.

Do the 1 and 2 byte constants for stack_ref, stack_set and stack_set2
cater for the maximum size of the stack?  Fbyte_code's maxdepth
parameter is a Lisp_Int, which suggests that the stack can be at least
as large as can be held in 29 bits.  Is there perhaps some other
restriction on the stack size?