lima/ppir: use ra_get_best_spill_node to select spill node

ra_get_best_spill_node is what other users of the mesa register
allocator use.
Switching to it now also fixes an infinite loop issue with ppir regalloc
with the ppir control flow patchset, and also provides a small gain over
the previous herusitic on number of spilled nodes testing with
shader-db.

Signed-off-by: Erico Nunes <nunes.erico@gmail.com>
Reviewed-by: Vasily Khoruzhick <anarsoul@gmail.com>

diff --git a/src/gallium/drivers/lima/ir/pp/regalloc.c b/src/gallium/drivers/lima/ir/pp/regalloc.c
index 4735dd407ebe58555918076a93c85100a17c48e7..0d6808d27fd60afbb7489a956bce2caf9577bb7a 100644 (file)
--- a/src/gallium/drivers/lima/ir/pp/regalloc.c
+++ b/src/gallium/drivers/lima/ir/pp/regalloc.c
@@ -545,20 +545,35 @@ static bool ppir_regalloc_spill_reg(ppir_compiler *comp, ppir_reg *chosen)
 static ppir_reg *ppir_regalloc_choose_spill_node(ppir_compiler *comp,
                                                  struct ra_graph *g)
 {
-   int max_range = -1;
+   int i = 0;
    ppir_reg *chosen = NULL;
 
    list_for_each_entry(ppir_reg, reg, &comp->reg_list, list) {
-      int range = reg->live_out - reg->live_in;
+      if (reg->spilled || reg->live_out == INT_MAX) {
+         /* not considered for spilling */
+         ra_set_node_spill_cost(g, i++, 0.0f);
+         continue;
+      }
+
+      /* It is beneficial to spill registers with higher component number,
+       * so increase the cost of spilling registers with few components */
+      float spill_cost = 4.0f / (float)reg->num_components;
+      ra_set_node_spill_cost(g, i++, spill_cost);
+   }
+
+   int r = ra_get_best_spill_node(g);
+   if (r == -1)
+      return NULL;
 
-      if (!reg->spilled && reg->live_out != INT_MAX && range > max_range) {
+   i = 0;
+   list_for_each_entry(ppir_reg, reg, &comp->reg_list, list) {
+      if (i++ == r) {
          chosen = reg;
-         max_range = range;
+         break;
       }
    }
-
-   if (chosen)
-      chosen->spilled = true;
+   assert(chosen);
+   chosen->spilled = true;
 
    return chosen;
 }