improve phi propagation

[r26437]

diff --git a/ir/be/benewalloc.c b/ir/be/benewalloc.c
index 9f71dff..ce8441b 100644 (file)
--- a/ir/be/benewalloc.c
+++ b/ir/be/benewalloc.c
@@ -1190,13 +1190,11 @@ static void adapt_phi_prefs(ir_node *phi)
  * After a phi has been assigned a register propagate preference inputs
  * to the phi inputs.
  */
-static void propagate_phi_register(ir_node *phi)
+static void propagate_phi_register(ir_node *phi, unsigned r)
 {
        int                    i;
        ir_node               *block = get_nodes_block(phi);
        int                    arity = get_irn_arity(phi);
-       const arch_register_t *reg   = arch_get_irn_register(phi);
-       unsigned               r     = arch_register_get_index(reg);
 
        for (i = 0; i < arity; ++i) {
                ir_node           *op   = get_Phi_pred(phi, i);
@@ -1204,16 +1202,17 @@ static void propagate_phi_register(ir_node *phi)
                ir_node           *pred;
                float              weight;
 
-               /* already a register assigned? then we can't influence it anyway */
-               /* TODO: what about splits which we might still do... */
-               if (arch_get_irn_register(op) != NULL)
-                       continue;
-
                pred   = get_Block_cfgpred_block(block, i);
                weight = get_block_execfreq(execfreqs, pred);
+               weight *= AFF_PHI;
+
+               if (info->prefs[r] >= weight)
+                       continue;
 
                /* promote the prefered register */
                info->prefs[r] += AFF_PHI * weight;
+               if (is_Phi(op))
+                       propagate_phi_register(op, r);
        }
 }
 
@@ -1349,7 +1348,9 @@ static void allocate_coalesce_block(ir_node *block, void *data)
                } else {
                        adapt_phi_prefs(node);
                        assign_reg(block, node, output_regs);
-                       propagate_phi_register(node);
+
+                       reg = arch_get_irn_register(node);
+                       propagate_phi_register(node, arch_register_get_index(reg));
                }
        }
        start = node;