Re: [Caml-list] a question about "ocamlopt" and "ocamldep"

[Matthias Puech <puech@cs.unibo.it>]

Hello,

This is consistent with how ocamlc/ocamlopt work: separate compilation 
is ensured the way you think by bytecode .cmo compilation: to build a 
module, you only need the *interfaces* of its dependencies, but it is 
unfortunately not ensured when compiling to native code, because of the 
global (inter-modules) optimizations performed (inlining AFAIK). Thus, 
to build a .cmx module, you need to be aware of the actual *code* of its 
dependencies.

I wonder now if it would be theoretically possible to do these 
optimization, not at compile-time, but delay them until link-time, when 
the code is fully known...

Cheers,
     -m

Le 03/13/2012 07:19 PM, Matej Košík a écrit :
> Hi,
>
> The "ocamldep" tool generates Makefile dependencies for both situations:
> - when we use "ocamlc"
> - as well as when we use "ocamlopt"
>
> Dependencies, generated for "*.cmo" files,
> are corresponding "*.cmi" files.
>
> This is not surprising.
>
> However, dependencies, generated for "*.cmx" files,
> are always other "*.cmx" files.
>
> This is surprising.
>
> Why "*.cmx" files do not depend on "*.cmi" files?
>
> I have noticed this in a bigger project but this phenomenon appear to
> happen for arbitrarily small projects.
>
> Consider the following ocamldep-generated couple of rules:
>
> src/ml2c/typing/printtyp.cmo: src/ml2c/typing/types.cmi \
>      src/ml2c/typing/primitive.cmi src/ml2c/typing/predef.cmi \
>      src/ml2c/typing/path.cmi src/ml2c/typing/outcometree.cmi \
>      src/ml2c/typing/oprint.cmi src/ml2c/utils/misc.cmi \
>      src/ml2c/parsing/longident.cmi src/ml2c/typing/ident.cmi \
>      src/ml2c/typing/env.cmi src/ml2c/typing/ctype.cmi \
>      src/ml2c/utils/clflags.cmi src/ml2c/typing/btype.cmi \
>      src/ml2c/parsing/asttypes.cmi src/ml2c/typing/printtyp.cmi
> src/ml2c/typing/printtyp.cmx: src/ml2c/typing/types.cmx \
>      src/ml2c/typing/primitive.cmx src/ml2c/typing/predef.cmx \
>      src/ml2c/typing/path.cmx src/ml2c/typing/outcometree.cmx \
>      src/ml2c/typing/oprint.cmx src/ml2c/utils/misc.cmx \
>      src/ml2c/parsing/longident.cmx src/ml2c/typing/ident.cmx \
>      src/ml2c/typing/env.cmx src/ml2c/typing/ctype.cmx \
>      src/ml2c/utils/clflags.cmx src/ml2c/typing/btype.cmx \
>      src/ml2c/parsing/asttypes.cmx src/ml2c/typing/printtyp.cmi
>
> The second rule seems to be unnecessarily demanding (unless it makes no
> sense to compile *.cmi files if we use ocamlopt). It should read:
>
> src/ml2c/typing/printtyp.cmx: src/ml2c/typing/types.cmi \
>      src/ml2c/typing/primitive.cmi src/ml2c/typing/predef.cmi \
>      src/ml2c/typing/path.cmi src/ml2c/typing/outcometree.cmi \
>      src/ml2c/typing/oprint.cmi src/ml2c/utils/misc.cmi \
>      src/ml2c/parsing/longident.cmi src/ml2c/typing/ident.cmi \
>      src/ml2c/typing/env.cmi src/ml2c/typing/ctype.cmi \
>      src/ml2c/utils/clflags.cmi src/ml2c/typing/btype.cmi \
>      src/ml2c/parsing/asttypes.cmi src/ml2c/typing/printtyp.cmi
>
> Shouldn't it?
>