[mythtv] Profile builds and debug code

Lawrence Rust lvr at softsystem.co.uk
Sun Mar 11 10:02:58 UTC 2012


On Sun, 2012-03-11 at 09:38 +1100, Jean-Yves Avenard wrote:
> Hi
> 
> On Sunday, 11 March 2012, Lawrence Rust <lvr at softsystem.co.uk> wrote:
> > I've been profiling some Myth functions using the
> --compile-type=profile
> > configure option and noticed that doing so results in Myth linking
> > against debug builds of Qt libs.  This is selected in settings.pro:
> >
> > profile:CONFIG += debug
> >
> > I was wondering what the reason for this was?
> 
> Ah that explains why in the mac packager we had to create symlinks
> from Qt libs to Qt debug libs...
> 
> >
> > I'm of the opinion that profiling should be performed on a release
> build
> > that's instrumented to record time spent etc.  If there's debugging
> code
> > left in then the profiling won't be representative or useful to
> > optimisers.  There's some existing support for removing debug code
> in
> > that configure currently defines NDEBUG for profiled builds.
> >
> > What do you think?  Should debug be removed or left in?
> 
> I would remove it for all configuration, including debug profile
> even...
> 
> Debugging myth rarely means you want to delve into Qt

There is one advantage in keeping the Qt debug libs for Myth debug
builds and that's the additional runtime checks and error messages.  For
instance unlocking a mutex or deleting a QObject from the wrong thread
trigger warnings.

-- 
Lawrence


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