etnaviv: nir: Add nir_texop_txd offset lowering

Implement offset lowering by computing the appropriate LOD from
gradients and adjusting coordinates accordingly.

Passes dEQP-GLES3.functional.shaders.texture_functions.texturegradoffset.* on GC7000.

Signed-off-by: Christian Gmeiner <cgmeiner@igalia.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35753>
1 file changed