pan/mdg: Add a nir pass to reorder store_output intrinsics

Real writeout stores, which break execution, need to be moved to after
dual-source stores, which are just standard register writes.

v2: Don't move stores forward, to avoid moving them to before where
    their source is written.

v3: Only reorder past dual-source stores.

Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5620>
1 file changed