aco/spill: only prevent rematerializable vars from being DCE'd if they haven't been renamed

The small DCE of the spiller only removes the original instructions
of rematerialized variables in case they are unused. If a variable
has been renamed, it cannot match any original instruction anymore.
Thus, the lookup is then unnecessary and can be omitted.

No fossil-db changes.

Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8055>
(cherry picked from commit ef4101d6d73614f4f41708050f963d6038f91e25)
2 files changed