10.03.07

Revisiting this issue, now that we're a typed scheme.

Our lexer and parser tables are generating a *lot* of code.
It'd be nice if there was some way to put this in the data segment.
We can probably even lay out a simple pxll_int[] of pre-populated data,
built the same way it would be in memory.

One issue, though. If we want to point directly at it, then internal
addresses will have to be set/adjusted at runtime... so we'll need
something similar to gc_relocate() to be run over it.  Is there some
way to have the loader do this automatically?  Hmmm.... it might be as
simple as walking over the array linearly, and applying an adjustment
to everything that looks like an address.

--- Design ---

So, what are our criteria for things that can be stored this way?
How about:

 common := immediate_literals | vector (common) | constructors (common)

This omits string literals, which may or may not be a big deal...

So at compile-time we'll walk over the data structure, building a
heap-like image of it.  We'll emit the thing as an array of pxll_int,
and point to it at compile-time, typed.

Upon entry to vm(), we run the address adjuster over the array,
adjusting anything that's a pointer by the base address.

--- Syntax ---

We could try to detect appropriate use points automatically, but
explicit beats implicit here, I think.

(define-literal (list:cons 1 (list:cons 2 (list:cons 3 (list:nil)))))

This would generate an array something like this:

[0x0220, 0x03, 0x10, 0x0220, 0x05, 0x18, ... ]
 ---- cons 1 ------  ----- cons 2 -----
0x0220 == len=2, tag=TC_USEROBJ+0

--- Mutability ---

Yeah, that's an ugly question.  Let's ignore it for now.

--- Implementation ---

Well, Scheme already brings QUOTE to the table, and we have some
code in there already for dealing with it.  It'd be nice if we
could extend that cleanly.  It'd also be nice to keep the type solver
out of it, since big data really slows it down.

Ideally we could keep it attached to the 'literal' node, all the way
through to the back end (separation of concerns)...

Ok, so how hard is it going to be to manually type these things?