[CMake] Detailed graphviz graph?

[Jan Wielemaker]

On 10/03/2018 09:53 AM, Eric Noulard wrote:
>
>
> Le mer. 3 oct. 2018 à 09:19, Jan Wielemaker <jan at swi-prolog.org
> <mailto:jan at swi-prolog.org>> a écrit :
>
>     Hi,
>
>     Debugging dependencies is not always easy.  The -graphviz option is a
>     nice try, but only seems to do the built-in target types.  Is there
>     some way to get the whole dependency graph, including custom targets
>     and possibly also the individual files?
>
>
> Not yet I guess:
>
> https://gitlab.kitware.com/cmake/cmake/issues/17960
>
>     Of course this can get huge.
>     Possibly there is some way to concentrate on anything relevant to a
>     particular target?
>
>
> Besides the custom target issue. I did craft a python script which loads
> the dependency graph spitted out by CMake
> and do various thing on it:
>
> - search if there exist a path between two targets
> - find all path between two targets
> - reduce the graph (transitive closure)
> etc...
> If you use ninja Generator you may try the browse or graph
> extra tool:
> https://ninja-build.org/manual.html
>
> This is generator specific and it may be difficult to follow your
> "original" CMake target in the generated ninja version.

Good to see this coming!  Yes, I use Ninja.  In fact I have some
suspicion I didn't see this problem when still using make (-j).  As
I dive into this I'll try to verify this.   If they really differ
I guess we are either dealing with timing differences or a broken
generator.

>     The problem I'm faced with is this:
>
>         - I have an ordinary executable target `swipl`
>         - To run, this requires a boot file `swipl.prc` that is created
>           by calling `swipl -b ...`
>
>
> Hum... I don't get it.
> For running? creating? target "swipl" you need to run it?
> There is a chicken & eggs problem or I misread what you said?

Nope. Poor wording by me. The executable swipl runs fine, but to really
do what one expects from a Prolog system it requires the parts of the
system written in Prolog to be compiled to Prolog VM code. To do so,
swipl contains a C defined mini compiler that can compile a subset of
the language, just enough to compile the real compiler written mostly in
Prolog. The result is dumped in the file swipl.prc. So, given swipl and
the Prolog boot files we first need to call

	swipl -O -b boot/init.pl # simplified

and next we can call `swipl arg ...` to run normal Prolog jobs such
as creating an index of the Prolog library.

>         - I'd like to run `swipl` for creating a library index file.
>
>     So, these targets need to be built in the order above.  It turns
>     out that sometimes step 3 runs before 2 completes.  At least, this
>     happens on MacOS using cmake 3.11.2.  So far I haven't seen it on
>     Linux (where I use 3.10).  The definition goes like this:
>
>     add_custom_command(
>           OUTPUT  swipl.prc
>           COMMAND swipl -O -b ${SWIPL_BOOT_ROOT}/init.pl
>           DEPENDS swipl ${SWIPL_BOOT_FILES}
>     )
>
>     add_custom_command(
>           OUTPUT  ${PL_LIB_INDEX}
>           COMMAND swipl -f none -g
>     "\"make_library_index('${SWIPL_LIBRARY_ROOT}')\"" -t halt
>           DEPENDS swipl.prc ${PL_LIB_FILES_ALL}
>     )
>
>     add_custom_target(prolog_products ALL
>           DEPENDS swipl.prc ${PL_LIB_INDEX}
>     )
>
>     The first specifies building swipl.prc, the second the index
>     file and the custom target ensures the default build will
>     create both files.  I don't see what is wrong and a visual
>     dependency graph might reveal this ...
>
>
> Are those three add_custom_xxx in the same directory?
> DEPENDS for custom_xxx do not cross directory.

Yip. In fact, they appear in (one of the) CMakeLists.txt together as you
see above.

I'll first have a look at the Ninja analysis tools. Thanks for the
hints. I'm pretty happy with cmake/ninja. Converting a huge complicated
project as introduction to cmake/ninja poses a bit steep learning curve
though :)

	Cheers --- Jan

>
> i.e:
> ``DEPENDS``
>    Reference files and outputs of custom commands created with
>    ``add_custom_command()`` command calls in the same directory
>    (``CMakeLists.txt`` file).  They will be brought up to date when
>    the target is built.
>
>
> --
> Eric