On AGX, the special register for front facing is inverted from its meaning in
APIs. We need to lower load_front_face to inot(load_back_face). Doing this in
the backend is trivial, but then we would miss out on algebraic optimizations
for the inot.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Acked-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11199>