pan/bi: Implement fquantize2f16
Implement as f2f32(f2f16(x)) with the conversions in flush-to-zero mode.
Accessing flush-to-zero mode on Bifrost is nontrivial: it is specified
per-clause, rather than per-instruction. I've opted to pipe support for ftz
clauses through the scheduler. This solution has two nice properties:
* It uses the native hardware for flushing subnormals, avoiding extra lowering.
* It's "smart" about scheduling around FTZ requirements, meaning we get good
code generated even for a shader that e.g. quantizes a vector.
With an unrelated scheduler fix, the *V2F32_TO_V2F16/+F16_TO_F32 operation fits
in a single tuple, minimizing the overhead of the special FTZ clause.
We'll have to do something a bit different for Valhall (FLUSH.f32), but we'll
worry about when we actually have PanVK brought up on Valhall.
Fixes dEQP-VK.spirv_assembly.instruction.compute.opquantize.*
Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Reviewed-by: Jason Ekstrand <jason.ekstrand@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16123>
7 files changed
