Hi, On Friday, February 15, 2013 15:00:24 Vadim Girlin wrote: > "LLVM backend is the future" is a pretty abstract argument. I prefer to > operate with real facts. After a year of LLVM backend development what > are the real benefits for the users? What are the real use cases where > the users might prefer LLVM backend? To me this situation looks like the > use of LLVM requires a lot more time and development efforts than the > custom solution, despite the initial expectations. Maybe you are right > and the LLVM backend will become the best alternative for users sometime > in the future, but I only have some today's results:
I am curious how this compares for shaders like used in git clone git://anarchy.freedesktop.org/~frohlich/PrecomputedAtmosphericScattering.git which is one of the bigger programs I know of. That one is taken from a Paper from INRIA regarding atmospheric scattering. The git archive is just some striped down variants of that to make it at least display with our radeon type drivers. You need float textures enabled in the configure step. The only variants that have a chance to run on the oss drivers is Main.noprecompute and Main.nogeometry once you compiled this dirty proof of concept files. That saied, the shaders there are far from programmed optimal IMO. But they render fast on the binary blobs. And I think they are a good example what you will find in the wild. People out there expect to find a decent compiler even in an OpenGL driver. I mean a compiler that does not just translate a tight pre optimized shader into the apropriate backend language, but a compiler that knows about all the tricks that are required to optimize more complex and less good written programs. Doing good optimizers - not only the backend ones - is a hard and longish busines which is easily underestimated. In the long term I would vote for your knowledge about these machines available in llvm to get the best of both worlds. my 2 cents... Mathias _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev