ocamlopt and ocamldep

From: Christian Lindig (lindig@ips.cs.tu-bs.de)
Date: Sat Sep 05 1998 - 14:33:27 MET DST

Date: Sat, 5 Sep 1998 14:33:27 +0200
Message-Id: <199809051233.OAA00550@infbsstq.ips.cs.tu-bs.de>
From: Christian Lindig <lindig@ips.cs.tu-bs.de>
To: Caml Mailing List <caml-list@inria.fr>
Subject: ocamlopt and ocamldep

The ocamldep utility in OCaml 2.0 creates for a file concept.mli that
uses modules Bitrelation and Bitset a dependency of the following

        concept.cmi: bitrelation.cmo bitset.cmo

When compiling for native code this causes uncessessary recompilations
of the files bitrelation.ml and bitset.ml:

        % make colibri.cmxa
        ocamlopt.opt -I ../libcolibri -I ../getopt -c stat.mli
        ocamlopt.opt -I ../libcolibri -I ../getopt -c stat.ml
   --> ocamlopt.opt -I ../libcolibri -I ../getopt -c bitset.ml
   --> ocamlopt.opt -I ../libcolibri -I ../getopt -c bitrelation.ml
        ocamlopt.opt -I ../libcolibri -I ../getopt -c intcode.mli
        ocamlopt.opt -I ../libcolibri -I ../getopt -c intcode.ml
   ==> ocamlc -I ../libcolibri -I ../getopt -c bitset.ml
   ==> ocamlc -I ../libcolibri -I ../getopt -c bitrelation.ml
   --> ocamlopt.opt -I ../libcolibri -I ../getopt -c concept.mli
        ocamlopt.opt -I ../libcolibri -I ../getopt -c concept.ml
        ocamlopt.opt -I ../libcolibri -I ../getopt -c lattice.mli
        ocamlopt.opt -I ../libcolibri -I ../getopt -c lattice.ml
        ocamlopt.opt -I ../libcolibri -I ../getopt -c context.ml
        ocamlopt.opt -I ../libcolibri -I ../getopt -a -o colibri.cmxa
            stat.cmx bitset.cmx bitrelation.cmx intcode.cmx concept.cmx
            lattice.cmx context.cmx
bitset.ml and bitrelation are already compiled to *.cmx, *.cmi, and
*.o. Because of the dependency generated by ocamldep they get
recompiled using the *byte* code compiler and thus new *.cmi files are
created as well.

This does not matter in most cases since OCaml compiles very fast. I
suspect the recompilation to cause subtle 'inconsistent assumptions
over interface' errors in conjunction with -unsave -noassert compiler
flags. However, I was not able to find a small example for this mail
that reproduces the error.

Should cmi-files depend on cmx-files when compiling for native code?
This would avoid uneccessary recompilations but would also make
integrating byte code compilation and native code compilation into one
Makefile much harder.

-- Christian

Christian Lindig http://www.cs.tu-bs.de/softech/people/lindig
                                  mail: lindig@ips.cs.tu-bs.de

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