Rob Clark of the Freedreno project has been spearheading the effort to add support for NIR as an alternate IR to Gallium3D. This would allow interested drivers in utilizing NIR where supported and skipping over TGSI -- the Gallium3D IR -- when going from, as an example. GLSL to NIR.
Rob Clark on Saturday posted the latest sixteen patches for this work and indicated that it should soon be ready to merge. Gallium3D drivers would still need to support TGSI, but this would just help for some cases when being able to jump over the intermediate translation step if preferring NIR. The patches also wire up the Mesa state tracker for supporting NIR as a possible IR.
Freedreno and VC4 have been the main Gallium3D drivers so far interested in making use of NIR, the intermediate representation now part of core Mesa and developed by Intel and now heavily leveraged by their open-source graphics driver.