RadeonSI Gallium3D Driver Adds GL_KHR_shader_subgroup Support

It's not too often these days seeing new OpenGL extensions come to Mesa drivers given their already robust coverage and not many new OpenGL extensions being introduced compared to the still-expanding Vulkan APIs. Overnight though RadeonSI Gallium3D saw GL_KHR_shader_subgroup support land.

GL_KHR_shader_subgroup has been around for several years but yet to see support by any of the Mesa drivers until now. This extension allows for shader subgroup shading language extensions in OpenGL and OpenGL ES. This extension adds APIs to allow querying the size of subgroups, indicate what shader stages support subgroup operations, subgroup features that ae supported, and related functionality. More details via the Khronos Registry.

Two years ago it was asked for Mesa drivers to support the KHR_shader_subgroup extension since the NVIDIA driver does and is needed for running a compute rasterizer demo. One month ago another user noted this extension would help them in their efforts.

AMD engineer Qiang Yu has now implemented the GL_KHR_shader_subgroup support and is passing the relevant OpenGL conformance test suite cases.

Now that the core Mesa changes for this extension have been added it likely won't be long before seeing other Mesa drivers support this extension. This newly-merged code will be part of the Mesa 24.3 release due out in mid-Q4.