Intel's Mesa Driver Now Uses NIR By Default For Vertex Shaders

As of today in Mesa Git -- and just in time for the Mesa 11.0 branching -- is the decision to enable usage of NIR by default for vertex shaders with the Intel driver.

The NIR intermediate representation for Mesa that's been in development for a while is now relied upon by the Mesa DRI driver for vertex shaders after previously being toyed with for Intel "Gen8" hardware and since April has been used by default for fragment shaders. With Mesa 11.0 being branched this weekend, the change is coming just in time rather than having to wait another three months before being rolled out as stable.

Jason Ekstrand of Intel made this change and in turning to NIR by default yields a reduction in the number of generated shader instructions for Haswell, Ivy Bridge, and Sandy Bridge hardware by a few percent. The changes for Iron Lake, G4x, and i965 are nominally impacted.

More details via this Git commit.