Soft FP64 Patches For Intel Sandy Bridge Allow ARB_gpu_shader_fp64

Elie Tournier, the GSoC student developer who last year worked via GSoC on "soft" FP64 double-precision support for older GPUs lacking the hardware capabilities, has posted patches wiring up his soft implementation for Intel "Gen 6" (Sandy Bridge) graphics thereby allowing ARB_gpu_shader_fp64 support.

Tournier was hired by Collabora earlier this year for continuing his work around soft FP64. Today he's posted some "request for comments" patches on implementing soft FP64 support in NIR for handling ARB_gpu_shader_fp64 with the Sandy Bridge era hardware. Ivy Bridge and newer can have native FP64 support. Wiring in ARB_gpu_shader_fp64 could allow Sandy Bridge to expose OpenGL 4.0+, albeit FP64 isn't too relevant for games and thus Linux gamers finding a GL4 game playable with SNB graphics could already override the extensions / GL level.

The work-in-progress patches can be found on Mesa-dev and amount to just under two thousand lines of code, nearly all of which is the NIR support for this emulated double-precision support.

Hopefully we'll see R600g have similar support eventually as there are many GPUs missing out on FP64 / OpenGL 4.0+ support due to not having this capability. Collabora though tends to not focus much on Radeon drivers specifically and R600g doesn't make use of NIR.