From 551c991606e543c3a264a762026f11348b37947e Mon Sep 17 00:00:00 2001 From: Paul Berry Date: Fri, 28 Sep 2012 14:21:38 -0700 Subject: [PATCH] register_allocate: don't consider trivially colorable registers for spilling. Previously, we considered all registers as candidates for spilling. This was counterproductive--for any registers that have already been removed from the interference graph, there is no benefit to spilling them, since they don't contribute to register pressure. This patch ensures that we will only try to spill registers that are still in the interference graph after register allocation has failed. This is consistent with the recommendations of the paper "Retargetable Graph-Coloring Register Allocation for Irregular Architectures", on which our register allocator is based. Reviewed-by: Matt Turner Reviewed-by: Eric Anholt --- src/mesa/program/register_allocate.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/src/mesa/program/register_allocate.c b/src/mesa/program/register_allocate.c index 97d4e331c91..88793dbdc1e 100644 --- a/src/mesa/program/register_allocate.c +++ b/src/mesa/program/register_allocate.c @@ -555,6 +555,13 @@ ra_get_best_spill_node(struct ra_graph *g) if (cost <= 0.0) continue; + /* Only consider registers for spilling if they are still in the + * interference graph (those on the stack have already been proven to be + * allocatable without spilling). + */ + if (g->nodes[n].in_stack) + continue; + benefit = ra_get_spill_benefit(g, n); if (benefit / cost > best_benefit) { -- 2.30.2