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.
This commit merges changes that were developed in the "racket7" repo.
See that repo (which is no longer modified) for a more fine-grained
change history.
The commit includes experimental support for running Racket on Chez
Scheme, but that "CS" variant is not built by default.
