Introduces a backwards dataflow analysis pass to determine when a
certain register is always written to prior to being read in a
similar manner to SSA liveness but performed after RA which we can
use to determine when we can insert (last) on src regs on A7XX.
Passing VK-CTS: dEQP-VK.pipeline.*
Signed-off-by: Mark Collins <mark@igalia.com>
Co-Authored-by: Job Noorman <jnoorman@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25077>