On Mon, Mar 12, 2018 at 6:18 AM, Samuel Pitoiset <samuel.pitoi...@gmail.com> wrote: > > > On 03/11/2018 04:41 PM, Marek Olšák wrote: >> >> On Thu, Mar 8, 2018 at 5:48 PM, Ian Romanick <i...@freedesktop.org> wrote: >>> >>> On 03/08/2018 06:50 AM, Samuel Pitoiset wrote: >>>> >>>> This pass moves load UBO operations just before their first use, >>>> loosely based on nir_opt_move_comparisons. >>> >>> >>> If I'm reading this correctly, it moves UBO loads closer to the first >>> use in the same block. My assumption is the benefit in the next patch >>> occurs because live ranges are smaller. It seems like this could also >>> hurt performance since it may be harder for the schedule to hide the >>> latency of the load when register pressure is not an issue. Have you >>> measured performance of running apps to see if this is an issue? >>> >>> I'm mostly asking because Jason had a series for global code motion that >>> does, in some cases, the opposite of this patch by moving UBO loads up >>> to earlier blocks. >> >> >> The pass is OK for LLVM, because LLVM does CSE across basic blocks, >> and it also does instruction scheduling within a block. >> >> radeonsi/tgsi does the same thing: it load uniforms from memory at >> every use. It sounds inefficient, but we found out that it's the best >> thing to do with LLVM. LLVM can move loads away from the use, but it >> doesn't move loads close to the use. > > > Exactly, RadeonSI does something similar. Though the shader-db result posted > by Timothy doesn't look very good for NIR, what do you think? >
The results are OK. Marek _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
