Mesa (master): lima/ppir: use ra_get_best_spill_node to select spill node

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Module: Mesa
Branch: master
Commit: 71fb721ca5b6761ff974b64d8f6d5efd51a691e9
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=71fb721ca5b6761ff974b64d8f6d5efd51a691e9

Author: Erico Nunes <nunes.erico at gmail.com>
Date:   Mon Aug 19 01:04:57 2019 +0200

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 at gmail.com>
Reviewed-by: Vasily Khoruzhick <anarsoul at gmail.com>

---

 src/gallium/drivers/lima/ir/pp/regalloc.c | 29 ++++++++++++++++++++++-------
 1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/src/gallium/drivers/lima/ir/pp/regalloc.c b/src/gallium/drivers/lima/ir/pp/regalloc.c
index 4735dd407eb..0d6808d27fd 100644
--- 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;
 }