Re: Troubles with Objcode and Storing JIT Pointers

[Noah Lavine]

Hello,

I just sent two patches which start to implement this to
address@hidden (The first patch is actually a small
documentation change, which I made only so I could rewrite it with
updated documentation in the second patch.)

The patch works as you described - SCM objcodes become five-word
objects, and all of the references get updated. I also had to change
all of the files that include static objcodes, which is why there are
changes to continuations.c, control.c, foreign.c, gsubr.c, and smob.c.

Unfortunately, I've hit a snag that I don't understand - if you try to
build it, you will see that control.c encounters an error in a
function that isn't changed by the patch. I am hoping that someone who
understands Guile's build system more than I do could look at that,
because I don't know what's happening.

There is one other issue with the patch that needs discussion, which
is what to initialize the extra cells to. Currently they're
initialized to NULL, and a comment describes a possible convention for
storing JIT code with them, but I'm not convinced it's the best way.
In particular, using an SCM symbol like 'no-jitcode for empty pointers
would be more self-documenting, but I wasn't sure if it would work in
statically-generated objcodes.

Thanks
Noah

On Tue, Jun 22, 2010 at 3:03 PM, Andy Wingo <address@hidden> wrote:
> On Tue 22 Jun 2010 00:23, Noah Lavine <address@hidden> writes:
>
>> If I may ask, do you already have patches or a git branch that adds [a
>> native code slot to objcode]? If so, what are you doing about the
>> embedded objcode issue? (Changing the bytecode to leave room for it,
>> or hiding the slot in the C code?)
>
> I do not have a patch, no. Feel free to implement :) Having not
> implemented it, I do not know exactly what's needed, but I would not put
> it in what is the struct scm_objcode, rather in the SCM value that
> includes the objcode.
>
> I don't know if we can somehow fit this in a "double cell" or if we need
> to have a five-word object (see scm_words ()).
>
> Andy
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