Nouveau Switches Over To NIR Backend By Default

As part of Mesa preparing to drop its old GLSL to TGSI code path and routing more Mesa drivers through using the NIR intermediate representation, the Nouveau Gallium3D driver code has switched to using this modern IR by default.

Emma Anholt made the change and landed it on Friday for enabling the NIR back-end by default with the Nouveau driver. Emma noted, "The NIR backend should reduce the compile time regression while providing more direct control over the IR we receive than going through NTT, while still providing the optimization that NIR-to-TGSI was bringing us."

The NIR results for the generated instructions are yielding some efficiency improvements for this open-source NVIDIA Linux graphics driver.

More details via this merge request that has now landed in Mesa 22.2.