Re: [Caml-list] Freeing dynamically loaded code

[Jacques Garrigue <garrigue@kurims.kyoto-u.ac.jp>]

From: Alain.Frisch@ens.fr
> > Let's make sure every closure generated from the library has an extra
> > local variable in it's environment, pointing to the head of the block
> > where that closure's code resides. This local variable need not even
> > be used, as long as it doesn't break the other locals in the function.
> >
> > So then every closure will carry an extra local variable, and those
> > are seen by the garbage collector, so the main codefile will exist as
> > long as any of those closures do.
> 
> I have been considering this idea too, but I think it does'nt work: sure,
> the GC won't free the code block, but it can still move it without
> updating the code pointer in the closure. Maybe this can be addressed
> by using a different GC tag to denote "movable" closures, so that the
> GC knows that the code pointer has to be translated by the same amount
> as the last slot (which is the pointer to the code block).

The variable doesn't need to point directly to the code block: it can
point to a finalized stub. The code is still statically allocated, but
when the stub is garbage collected the code is freed.

So this should work.
But I'm not candidate to try it :-)

Jacques Garrigue

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