On Thursday 24 September 2009 00:15:14 you wrote:
> make program.nc uses original ocamlopt
>
> make program.th uses the newly built ocamlopt with the necessary
> options (lib links)
>
> then you can compare program.nc and program.th

Aha! Progress, but now I get errors:

$ make matmul.th
../out/bin/ocamlopt -ccopt -march=native -ccopt -mtune=native -ccopt -O4 -I /home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../out/lib/ocaml/ -I /home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../runtime/gcs/sc_par /home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../runtime/gcs/sc_par/gci.o -cclib -lgc -cclib  -g -thread  
unix.cmxa threads.cmxa graphics.cmxa -verbose -compact -rectypes -inline 
100 -fno-PIC  -cclib -lunix -cclib -lpthread "matmul.ml" -o "matmul.th"
File "matmul.ml", line 25, characters 8-13:
Warning Y: unused variable count.
File "matmul.ml", line 26, characters 8-16:
Warning Y: unused variable last_col.
+ as -o matmul.o /tmp/camlasm081590.s
+ as -o /tmp/camlstartupdac3e2.o /tmp/camlstartup8f7152.s
+ 
gcc   -o 'matmul.th' -I'/home/jdh30/src/ocaml/parallel/oc4mc-20090823/ocaml-3.10.2/../out/lib/ocaml' -march=native -mtune=native -O4 '/tmp/camlstartupdac3e2.o' '/home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../out/lib/ocaml/std_exit.o' 'matmul.o' '/home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../out/lib/ocaml/graphics.a' '/home/jdh30/src/ocaml/parallel/oc4mc-20090823/ocaml-3.10.2/../out/lib/ocaml/threads/threads.a' '/home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../out/lib/ocaml/unix.a' '/home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../out/lib/ocaml/stdlib.a'  '-L/home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../out/lib/ocaml/' '-L/home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../runtime/gcs/sc_par' '-L/home/jdh30/src/ocaml/parallel/oc4mc-20090823/ocaml-3.10.2/../out/lib/ocaml/threads' '-L/home/jdh30/src/ocaml/parallel/oc4mc-20090823/ocaml-3.10.2/../out/lib/ocaml' '-lgraphics' '-lX11' '-lthreadsnat' '-lunix' '-lpthread' '-lunix' '/home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../runtime/gcs/sc_par/gci.o' '-lgc' '-g' '-lunix' '-lpthread' '/home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../out/lib/ocaml/libasmrun.a' -lm  -ldl
/home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../out/lib/ocaml/libasmrun.a(memory.o): 
In function `gc_end_roots':
memory.c:(.text+0x10): multiple definition of `gc_end_roots'
/home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../runtime/gcs/sc_par/gci.o:/home/jdh30/src/ocaml/parallel/oc4mc-20090823/runtime/gcs/sc_par/gci.c:948: 
first defined here
/home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../out/lib/ocaml/libasmrun.a(memory.o): 
In function `gc_begin_roots':
memory.c:(.text+0x12): multiple definition of `gc_begin_roots'
/home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../runtime/gcs/sc_par/gci.o:/home/jdh30/src/ocaml/parallel/oc4mc-20090823/runtime/gcs/sc_par/gci.c:947: 
first defined here
/home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../out/lib/ocaml/libasmrun.a(finalise.o): 
In function `caml_final_do_strong_roots':
finalise.c:(.text+0x0): multiple definition of `caml_final_do_strong_roots'
/home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../runtime/gcs/sc_par/gci.o:/home/jdh30/src/ocaml/parallel/oc4mc-20090823/runtime/gcs/sc_par/gci.c:301: 
first defined here
/home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../runtime/gcs/sc_par/gci.o: 
In function `stop_the_world':
gci.c:(.text+0x38e): undefined reference to `caml_all_threads'
gci.c:(.text+0x403): undefined reference to `caml_all_threads'
gci.c:(.text+0x410): undefined reference to `caml_all_threads'
gci.c:(.text+0x48a): undefined reference to `caml_all_threads'
/home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../runtime/gcs/sc_par/gci.o: 
In function `resume_the_world':
gci.c:(.text+0x4c4): undefined reference to `caml_all_threads'
/home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../runtime/gcs/sc_par/gci.o:gci.c:
(.text+0x57c): more undefined references to `caml_all_threads' follow
/home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../runtime/gcs/sc_par/gci.o: 
In function `termination_action':
gci.c:(.text+0x1e94): undefined reference to `remove_thread_from_list'
/home/jdh30/src/ocaml/parallel/oc4mc-20090823/tests/../runtime/gcs/sc_par/gci.o: 
In function `gc_terminate_local':
gci.c:(.text+0x1fe5): undefined reference to `remove_thread_from_list'
collect2: ld returned 1 exit status
Error during linking
make: *** [matmul.th] Error 2

-- 
Dr Jon Harrop, Flying Frog Consultancy Ltd.
http://www.ffconsultancy.com/?e