Intel Mesa Driver Starts Using NIR By Default For Fragment Shaders

Intel's i965 Mesa driver has begun using the NIR intermediate representation by default when dealing with fragment shaders.

Intel developers have been working for months on this NIR intermediate representation to ultimately replace GLSL IR. The Freedreno and VC4 Gallium3D drivers have also jumped aboard the NIR train. Intel's driver hasn't enabled NIR by default but now it's finally done so for fragment shader handling.

Jason Ekstrand of Intel changed the INTEL_USE_NIR environment variable default to true for fragment shaders. Using NIR leads to a reduction in the number of produced shader instructions going back many Intel hardware generations though in some cases there's slightly more instructions generated. Details via this Git commit.