[Mesa-dev] last call for autotools

[Dylan Baker]

Quoting Axel Davy (2018-12-12 14:31:34)
> On 12/12/2018 23:06, Dylan Baker wrote:
> > Quoting Marek Ol\u0161k (2018-12-12 13:07:10)
> >> On Wed, Dec 12, 2018 at 3:52 PM Rob Clark <robdclark at gmail.com> wrote:
> >>
> >>      On Wed, Dec 12, 2018 at 3:45 PM Marek Ol\u0161k <maraeo at gmail.com> wrote:
> >>      >
> >>      > On Wed, Dec 12, 2018 at 3:37 PM Rob Clark <robdclark at gmail.com> wrote:
> >>      >>
> >>      >> On Wed, Dec 12, 2018 at 3:13 PM Bas Nieuwenhuizen
> >>      >> <bas at basnieuwenhuizen.nl> wrote:
> >>      >> >
> >>      >> > On Wed, Dec 12, 2018 at 8:59 PM Marek Ol\u0161k <maraeo at gmail.com> wrote:
> >>      >> > >
> >>      >> > > There are 2 issues with meson:
> >>      >> > > * -DDEBUG is not present in debugoptimized builds.
> >>      >> >
> >>      >> > Do people expect -DDEBUG for debugoptimized? I would think that debug
> >>      >> > optimized would be an optimized build with debug symbols, but not
> >>      >> > expensive checks & asserts, which would match the current
> >>      >> > debugoptimized build?
> >>      >>
> >>      >> please, no -DDEBUG for debugoptimized.. I use that when I want debug
> >>      >> syms but not (for example) nir_validate and other expensive checks.
> >>      >
> >>      >
> >>      > If nir_validate is so bad, perhaps it shouldn't be run at all. If you
> >>      work on NIR and it's not important for you to run nir_validate, perhaps it
> >>      shouldn't be run at all. It doesn't have anything to do with build systems.
> >>      >
> >>
> >>      I do actually want it enabled when I piglit/deqp.. for which I use
> >>      debug builds. But I don't want it if I'm profiling or valgrinding,
> >>      where I use debugoptimized..
> >>
> >>
> >> At some point, DEBUG will be replaced by !NDEBUG.
> >>
> >> Marek
> > The whole point of DEBUG is to hide really expensive checks like nir validate.
> > If there are are asserts hidden behind debug that's wrong, those should be
> > behind !NDEBUG, that's what NDEBUG is for. We've talked about renaming DEBUG
> > because it's confusing, something like EXPENSIVE_DEBUG or EXPENSIVE_VALIDATION
> > or something along those lines.
> >
> > The thread I linked you to previously has extensive discussion of why DEBUG was
> > removed from the debugoptimized build.
> >
> > For CFLAGS: yes, environment variables are only read during the initial
> > configuration by design, they basically exist for compatibility with autotools.
> > You want to use -Dc_args and -Dcpp_args (for CFLAGS and CXXFLAGS respectively)
> > these are read by meson, meson configure, and meson reconfigure.
> >
> > Dylan
> 
> Hi,
> 
> Currently nine debug log (enabled with NINE_DEBUG=all) only works with 
> --enable-debug build.
> 
> There is quite a performance difference with autotools when you build 
> with --enable-debug. However we often need users to use NINE_DEBUG to 
> produce logs for issues.
> 
> These sorts of things should be made to work with debugoptimized if 
> possible.
> 
> Currently we hide that against the DEBUG env var. Should that be 
> replaced by !NDEBUG when autotools support is killed ?
> 
> Axel
> 

Likely it means we (the mesa community) needs to have a discussion about -DDEBUG
in general. We (intel) use it to hide things that will make performance suck,
but it seems like others are using it just to hide debugging information. I'll
send a separate mail about DEBUG.

Dylan
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