[Caml-list] Shared object generation patch.

[Caml-list] Shared object generation patch.

[malc]

Hello,

At http://algol.prosalg.no/~malc/scaml you will find a patch against
OCaml 3.02 and some information suitable for producing shared objects
on i386 ELF systems.

-- 
mailto:malc@pulsesoft.com

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[Caml-list] Shared object generation patch feedback

[Jeff Henrikson]

> At http://algol.prosalg.no/~malc/scaml you will find a patch against
> OCaml 3.02 and some information suitable for producing shared objects
> on i386 ELF systems.

Nice!  It compiled right out of the box, no unexpected difficulties.

Is there a way to get a asm runtime in a shared lib?  (Either for the purposes of having small executables or for calling from
non-caml)

I am having a hard time understanding how this works due to the fact that I don't understand the ocaml calling/symbol naming
convention.  I've been reading some assembly intermediary files and nm dumps, but I am still confused and am wondering if there's
some general documentation somewhere.

Here's an example of something that confuses me.  I make a file testlib.ml:

> open Printf;;
>
> let rec print_int_list x =
>   match x with
>     [] -> ()
>   | hd::tl -> printf "%d " hd; (print_int_list tl);;
>
> let rec mymap f l =
>   match l with
>     [] -> []
>   | hd::tl -> (f hd)::(mymap f tl);;

and I nm testlib.so and get

> 000010c0 T Testlib_code_begin
> 0000118a T Testlib_code_end
> 000023f4 D Testlib_data_begin
> 00002424 D Testlib_data_end
> 00001170 T Testlib_entry
> 00002428 D Testlib_frametable
> 00001100 T Testlib_mymap_53
> 000010c0 T Testlib_print_int_list_49

So I wonder:

1) where do the numbers 53 and 49 come from, and do I care?  For example, if they are arbitrary (as I surmise) and socked away in
testlib.so.cmxa, then don't I get screwed if I try to build an program linked against testlib.so.cmxa and then decide that I want
to change the implementation of testlib?  If so, is there a way to define a symbol table just from an mli?  (A .so.cmi file or
something?)  This command only produces a .cmi:

ocamlopt -shared -o foo.so foo.mli

2) what do the other entry points mean, eg Testlib_entry, and do I care?

Great work if this actually is heading down the path to real system deployment with ocaml!


Jeff Henrikson



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Re: [Caml-list] Shared object generation patch feedback

[malc]

On Sun, 7 Oct 2001, Jeff Henrikson wrote:

> > At http://algol.prosalg.no/~malc/scaml you will find a patch against
> > OCaml 3.02 and some information suitable for producing shared objects
> > on i386 ELF systems.
> 
> Nice!  It compiled right out of the box, no unexpected difficulties.
> 
> Is there a way to get a asm runtime in a shared lib?  (Either for the purposes of having small executables or for calling from
> non-caml)
Yes. (ocamlopt -shared ... -ccopt "-L`ocamlc -where` -lasmrun -u caml_main")

> 
> I am having a hard time understanding how this works due to the fact that I don't understand the ocaml calling/symbol naming
> convention.  I've been reading some assembly intermediary files and nm dumps, but I am still confused and am wondering if there's
> some general documentation somewhere.
> 
> Here's an example of something that confuses me.  I make a file testlib.ml:
> 
> > open Printf;;
> >
> > let rec print_int_list x =
> >   match x with
> >     [] -> ()
> >   | hd::tl -> printf "%d " hd; (print_int_list tl);;
> >
> > let rec mymap f l =
> >   match l with
> >     [] -> []
> >   | hd::tl -> (f hd)::(mymap f tl);;
> 
> and I nm testlib.so and get
> 
> > 000010c0 T Testlib_code_begin
> > 0000118a T Testlib_code_end
> > 000023f4 D Testlib_data_begin
> > 00002424 D Testlib_data_end
> > 00001170 T Testlib_entry
> > 00002428 D Testlib_frametable
> > 00001100 T Testlib_mymap_53
> > 000010c0 T Testlib_print_int_list_49
> 
> So I wonder:
> 
> 1) where do the numbers 53 and 49 come from, and do I care?  For example, if they are arbitrary (as I surmise) and socked away in
> testlib.so.cmxa, then don't I get screwed if I try to build an program linked against testlib.so.cmxa and then decide that I want
> to change the implementation of testlib?  If so, is there a way to define a symbol table just from an mli?  (A .so.cmi file or
> something?)  This command only produces a .cmi:
OCaml add those suffixes for variety of reasons, something must be done
about it (on the linking stage), if people want -shared to take off.

> 
> ocamlopt -shared -o foo.so foo.mli
Naturally. There is nothing to compile, leave alone link here :)

> 
> 2) what do the other entry points mean, eg Testlib_entry, and do I care?
Those are module toplevel forms. _frametable, _code[data]_begin[end] are
used by GC, equality comparisions, marshaling etc.

> 
> Great work if this actually is heading down the path to real system deployment with ocaml!
There is still a lot to be done, to make it really useful. But thanks for
encouragment, i needed it.
> 
> 
> Jeff Henrikson

-- 
mailto:malc@pulsesoft.com

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