[CMake] Customize dependencies scanned by CMake

[David Cole]

See this command:
http://cmake.org/cmake/help/cmake-2-8-docs.html#command:include_regular_expression

If you can match many of the "header files that rarely, if ever, change"
with a regular expression based on directory and file name patterns, then
you can reduce the number of entries in the generated makefiles
significantly.


HTH,
David


On Sat, Jan 15, 2011 at 7:57 AM, Dieter Oberkofler <
doberkofler.lists at gmail.com> wrote:

> I'm using CMake 2.8.3 using makefiles for the OSX and Windows platform.
>
> I very much like CMake but unfortunately the build performance consistently
> causes some problems.
>
> And the main performance problem is the absolutely correct but painfully
> slow dependency checking.
> In a large (Qt/C++) project a single source file has over 1500 include
> dependencies summing up to a "depend.make" file with several million lines.
> Almost all (typically 99%) of the include dependencies are not needed in
> real life because they come from Qt or other static frameworks but
> dramatically slow down the build process.
>
> I do know that CMake offers the /fast option but this removes all
> dependencies and although it is 3-5 times faster, manually "optimizing" the
> content of "depend.make" makes the build up to 20 times faster.
> Why is the /fast option not (at least) as fast as a manually "optimized"
> "depend.make"?
>
> Is there a way to:
> - customize what includes should be parsed?
> - exclude dependency trees?
> - limit the recursion level?
>
> or any other option to solve this problem?
>
> Thank you!
>
>
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