pan/bi: Mark bi_postra_liveness_ins as MUST_CHECK

Post-RA liveness relies on the caller updating the live variable with the
results of bi_postra_liveness_ins. It is not automatic, as with regular
liveness. This means ignoring the result of bi_postra_liveness_ins is surely an
error. Mark it as MUST_CHECK to catch that error at compile time.

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17091>

src/panfrost/bifrost/bi_opt_dce.c

@@ -77,7 +77,7 @@ bi_opt_dead_code_eliminate(bi_context *ctx)
 
 /* Post-RA liveness-based dead code analysis to clean up results of bundling */
 
-uint64_t
+uint64_t MUST_CHECK
 bi_postra_liveness_ins(uint64_t live, bi_instr *ins)
 {
         bi_foreach_dest(ins, d) {

src/panfrost/bifrost/compiler.h

@@ -1133,7 +1133,7 @@ void bi_compute_liveness(bi_context *ctx);
 void bi_liveness_ins_update(uint8_t *live, bi_instr *ins, unsigned max);
 
 void bi_postra_liveness(bi_context *ctx);
-uint64_t bi_postra_liveness_ins(uint64_t live, bi_instr *ins);
+uint64_t MUST_CHECK bi_postra_liveness_ins(uint64_t live, bi_instr *ins);
 
 /* Layout */