util/ra: Conflict-aware round-robin heuristic to reduce likelihood of false dependencies.for-kayden

1 files changed, 7 insertions, 3 deletions

diff --git a/src/util/register_allocate.c b/src/util/register_allocate.c
index 8af93c0406c..035993db48a 100644
--- a/src/util/register_allocate.c
+++ b/src/util/register_allocate.c
@@ -563,7 +563,8 @@ ra_select(struct ra_graph *g)
        */
       for (ri = 0; ri < g->regs->count; ri++) {
          r = (start_search_reg + ri) % g->regs->count;
-         if (!reg_belongs_to_class(r, c))
+         if (!reg_belongs_to_class(r, c) ||
+             BITSET_TEST(g->regs->regs[r].conflicts, start_search_reg))
 	    continue;
 
 	 /* Check if any of our neighbors conflict with this register choice. */
@@ -600,8 +601,11 @@ ra_select(struct ra_graph *g)
        * dense packing strategy.
        */
       if (g->regs->round_robin &&
-          g->stack_count - 1 <= g->stack_optimistic_start)
-         start_search_reg = r + 1;
+          g->stack_count - 1 <= g->stack_optimistic_start) {
+         for (start_search_reg = r;
+              BITSET_TEST(g->regs->regs[r].conflicts, start_search_reg);
+              start_search_reg++);
+      }
    }
 
    return true;