pan/bi: Implement unpack_64_2x32

This duplicates the lowering from nir_lower_packing. However, nir_lower_packing
also lowers a pile of other instructions that we do implement natively, and this
is easier than adding a bunch of knobs to nir_lower_packing to get just what we
need.

Fixes test-printf address_space_4.

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18656>

src/panfrost/bifrost/bifrost_nir_algebraic.py

@@ -69,6 +69,10 @@ algebraic_late = [
     # directly to the hardware.
     (('f2i8', a), ('i2i8', ('f2i16', a))),
     (('f2u8', a), ('u2u8', ('f2u16', a))),
+
+    # XXX: Duplicate of nir_lower_pack
+    (('unpack_64_2x32', a), ('vec2', ('unpack_64_2x32_split_x', a),
+                                     ('unpack_64_2x32_split_y', a))),
 ]
 
 # Handling all combinations of boolean and float sizes for b2f is nontrivial.