lima/ppir: Add undef handling

Add a ppir dummy node for nir_ssa_undef_instr, create a reg for it and mark
it as undefined, so that regalloc can set it non-interfering to avoid
register pressure.

Signed-off-by: Andreas Baierl <ichgeh@imkreisrum.de>
Reviewed-by: Vasily Khozuzhick <anarsoul@gmail.com>
Reviewed-by: Erico Nunes <nunes.erico@gmail.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/src/gallium/drivers/lima/ir/pp/regalloc.c b/src/gallium/drivers/lima/ir/pp/regalloc.c
index c7012294178..dbec70acb4b 100644
--- a/src/gallium/drivers/lima/ir/pp/regalloc.c
+++ b/src/gallium/drivers/lima/ir/pp/regalloc.c
@@ -612,7 +612,10 @@ static bool ppir_regalloc_prog_try(ppir_compiler *comp, bool *spilled)
       list_for_each_entry_from(ppir_reg, reg2, reg1->list.next,
                                &comp->reg_list, list) {
          bool interference = false;
-         if (reg1->live_in < reg2->live_in) {
+
+         if (reg1->undef || reg2->undef)
+            interference = false;
+         else if (reg1->live_in < reg2->live_in) {
             if (reg1->live_out > reg2->live_in)
                interference = true;
          }