pan/bi: Add src/dest fields to bifrost_instruction

...along with some helpers to generate indices. The indexing scheme is
mostly a copypaste from Midgard, except we specifically reserve 0 as the
sentinel (midgard uses ~0 for this which has always been a pain point).

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4061>
1 file changed