[Mesa-dev] RFC: LLVM, -fno-rtti, and Haiku

[Kenneth Graunke]

On 10/10/2013 04:27 PM, Alexander von Gluck IV wrote:
> 
> In llvm.py -fno-rtti is always a build flag if LLVM present >= 3.2
> 
> This breaks everything on our end (missing rtti related symbols) in our
> C++ libGL.so as Haiku uses dynamic casts.
> 
> We build our LLVM packages with rtti (REQUIRES_RTTI=1).
> 
> Not 100% sure why we're forcing no-rtti if LLVM >= 3.2.
> "llvm-config --cxxflags" should always show "-fno-rtti" if REQUIRES_RTTI=1
> wasn't set at build time. If REQUIRES_RTTI was set, -fno-rtti is removed
> from the llvm-config cxxflags.
> 
> It was originally added here:
> http://cgit.freedesktop.org/mesa/mesa/commit/scons/llvm.py?id=d37ae642034bcaca39492c1eb75b029fb27ceffb
> 
> My solutions are either removing the forced -fno-rtti, or wrapping it
> with a platform != 'Haiku'
> 
> Thoughts?
> 
>  -- Alex

I would love to see us build with -fno-rtti for all Linux builds.  I've
been meaning to try that and measure the impact.

--Ken