Am Donnerstag, den 19.01.2017, 13:24 +0100 schrieb Christoph Höger:
Could you elaborate a little bit, how that should work? AFAIK, e.g. the curry helpers are generated in Cmmgen, which is absolutely sensible, since they certainly do not depend on the machine architecture, right? So when and where does the linker use this generation?

What I know is that the linker gathers up the required functions from the cmx and cmxa files. E.g. that could be a helper that returns the closure for a 5-argument function that is called with only 3 arguments. Such helpers are only needed once for the whole program.


To motivate my question a little bit, I was wondering whether I could load two different OCaml executables inside the same process by using LLVM's runtime linker. In principle, when I load them, they should be able to cooperate across the shared heap, but otherwise live in total isolation (in particular their garbage collectors should not interfere).

Well, you could try whether the object file emitted by "ocamlopt -output-obj" works. This object contains everything but the main program and the additional libraries needed (like libasmrun).

Gerd


On Thu, Jan 19, 2017 at 1:11 PM, Gerd Stolpmann <info@gerd-stolpmann.de> wrote:
Am Donnerstag, den 19.01.2017, 10:44 +0100 schrieb Christoph Höger:
Dear all,

consider a simple test program:

  let _ = Printf.printf "Hello world!\n"

I can generate the relevant assembly just fine, e.g.:

ocamlopt -dstartup -S test.ml
gcc -c a.out.startup.s -c

But I cannot link it:

gcc a.out.startup.o -L$(ocamlc -where) -lasmrun_shared
....
a.out.startup.o(.data+0x6e8): error: undefined reference to 'camlStd_exit__frametable'
collect2: Fehler: ld gab 1 als Ende-Status zurück
distcc[9960] ERROR: compile (null) on localhost failed

It seems that the whole Pervasives is missing (which is kind of expected).

How do I link it, manually? Where are the relevant object files?

There's stdlib.a in the OCaml library directory.

This is not the only problem with your approach. The OCaml linker generates a number of functions that are global to the whole OCaml program (in particular currying helpers). These are first known at link time and thus generated that late. AFAIK you cannot generate these functions outside the linker step. 

The only official way how to turn OCaml code into a linkable object is described here: http://caml.inria.fr/pub/docs/manual-ocaml/intfc.html#s%3Aembedded-code

Gerd


thanks,

Christoph

-- 
------------------------------------------------------------
Gerd Stolpmann, Darmstadt, Germany    gerd@gerd-stolpmann.de
My OCaml site:          http://www.camlcity.org
Contact details:        http://www.camlcity.org/contact.html
Company homepage:       http://www.gerd-stolpmann.de
------------------------------------------------------------




-- 
------------------------------------------------------------
Gerd Stolpmann, Darmstadt, Germany    gerd@gerd-stolpmann.de
My OCaml site:          http://www.camlcity.org
Contact details:        http://www.camlcity.org/contact.html
Company homepage:       http://www.gerd-stolpmann.de
------------------------------------------------------------