In the future we will have many ALU instructions passing shared
registers to each other, and surrounding them each with moves to/from
shared registers will severely bloat the IR size coming out of NIR and
make more pointless work for copy propagation. Instead, do something
more like the ACO approach and allow values stored in the hash table to
be shared, and move the burden of emitting a mov to non-shared to
ir3_get_src(). We will then use ir3_get_src_shared() or
ir3_get_src_maybe_shared() as appropriate in cases where we can handle
shared registers or where we can handle both.
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22075>
3bec9e684d