Really, `raco demod` is adapted here to work with any linklet-based VM
by compiling modules to machine-independent form, which is essentially
a wrapper around linklet S-expressions. The BC-specific implementation
remains in place, and it has the advantage of being able to work with
existing module compilations, while the implementation based on
machine-independent form must recompile all modules before attempting
to combine them (but that recompilation is easily cached).
Use `--work <dir>` to use `<dir>` as a cache for multiple
demodularizations.
Getting `raco demod` to work involved several incidental improvements:
* make `racket/linklet` work with machine-independent forms;
* add `linklet-body-reserved-symbol?`;
* fix schemify for linklets that have unexported definitions (which
the expander never generates, but the demodularizer does);
* add `current-multi-compile-any` to expose CM's multi-target
compilation mode programmatically; and
* repair a bug in CS JIT mode.
The demodularizer could be a lot smarter to prune demodularized code
before sending it off to the compiler. Of course, the compiler should
be able to figure out improvements itself, but sending a smaller chunk
of code to the compiler can avoid the hybrid interpreter--compiler
mode that is used for large linklets and that prevents optimizers like
cp0 from doing much to prune definitions.
The demodularizer has a lot in common with the expander's flattener
that is used for bootstrapping, and a smarter demodularizer would have
even more in common. It would be nice to have one implementation
instead of two.
