This unifies the dynamic (SSO) and fixed (linked together) versions.
We emit piles of NIR as if we were doing the dynamic version, but
replace the tess config field access with constant values. It all
should optimize away back to something reasonable. We lower these
directly to URB read/write intrinsics.
It also rewrites the dynamic version to directly read/write the URB
rather than going through temporaries. The old version was broken
in that tessellation control shader invocations can technically use
the shared output area for cross-invocation data sharing with barriers,
although doing so using the built-in tesslevel patch outputs is very
unlikely.
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/38482>
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