We have competent lowering in NIR already available.
Drivers exposing CAP_DOUBLES but not SHADER_CAP_DROUND:
- d3d12 (NIR lowers ~0 if the underlying impl doesn't do floats)
- svga (Now sets the NIR lowering options)
- softpipe (Doesn't do GL4 so you can't use doubles anyway)
- llvmpipe (Lowers dround_even in NIR and passees the rest through
successfully)
- zink (NIR lowers ~0 if the underlying impl doesn't do floats,
otherwise passes things through successfully, except needed
dround_even lowering to avoid lavapipe regression with
native doubles)
- r600 (sets NIR rounding lowering flags, and lowers all fsign)
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Acked-by: Faith Ekstrand <faith.ekstrand@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25777>
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