On Tue, 2016-07-26 at 22:56 -0700, Matt Turner wrote: > On Tue, Jul 26, 2016 at 10:20 PM, Timothy Arceri > <timothy.arc...@collabora.com> wrote: > > The ultimate goal is to be able to convert to NIR and make use of > > its > > optimisations before assigning varying and uniform locations. This > > should allow us to start removing some of the GLSL IR optimisation > > passes. > > I'm very excited about this!
:) > > > This series falls short of making use of NIR because > > lower_packed_varyings() > > modifies the IR after we assign varying locations. I can see two > > ways > > around this, listing them in increasing difficultly level they > > would be: > > > > - replacing the current packing pass with one that follows the > > packing > > rules of ARB_enhanced_layouts this would mean we can no longer pack > > across slots and matrix and array packing effectivness would be > > slightly > > decreased. > > - write a NIR packing pass. > > Specifically a NIR implementation of lower_packed_varyings(), right? Correct. I should have also mentioned that after assigning the locations in the GLSL IR linker my current plan would be to insert these locations into the existing NIR that gets created. I haven't figured out how I would do this just yet but I'm hoping it can be done and without being too hacky. Hence why is why we could do option 1 as we would just be updating component and location fields rather than altering the IR. > > > > > Even without converting to NIR this series solves a number of the > > other > > problems with converting to NIR earlier and provides a nice shader- > > db > > improvement on its own. > > > > Broadwell shader-db results: > > > > total instructions in shared programs: 8651650 -> 8644415 (-0.08%) > > instructions in affected programs: 38754 -> 31519 (-18.67%) > > total loops in shared programs: 2085 -> 2085 (0.00%) > > helped: 320 > > HURT: 0 > > GAINED: 0 > > Impressive. > > > Ivybridge reported no difference. > > I suspect that's because Ivybridge's vertex shader is vec4, and we > don't dead code eliminate individual *components* of varyings, > whereas > on Broadwell with scalar vertex shaders we're able to eliminate those > dead components. Yeah I was wondering why at first I thought I forgot to switch branches but after looking at the code I assumed this to be the case thanks. > > Thanks so much for working on this! No problem. I'm happy to let someone else take this further if they would like to, I just thought I would see how hard it would be to do. > _______________________________________________ > mesa-dev mailing list > mesa-dev@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/mesa-dev _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
