shrink load mode if not all bits are used

diff --git a/ir/ir/iropt.c b/ir/ir/iropt.c
index d37db02..f9958a1 100644 (file)
--- a/ir/ir/iropt.c
+++ b/ir/ir/iropt.c
@@ -5597,6 +5597,26 @@ static ir_node *transform_node_Conv(ir_node *n)
                }
        }
 
+       /* shrink mode of load if possible. */
+       if (is_Proj(a)) {
+               ir_node *pred = get_Proj_pred(a);
+               if (is_Load(pred)) {
+                       /* only do it if we are the only user (otherwise the risk is too
+                        * great that we end up with 2 loads instead of one). */
+                       ir_graph *irg = get_irn_irg(n);
+                       if (edges_activated(irg) && get_irn_n_edges(a) == 1) {
+                               ir_mode *load_mode = get_Load_mode(pred);
+                               if (!mode_is_float(load_mode) && !mode_is_float(mode) &&
+                                       get_mode_size_bits(mode) <= get_mode_size_bits(load_mode)
+                                       && !be_get_backend_param()->byte_order_big_endian) {
+                                       set_Load_mode(pred, mode);
+                                       set_irn_mode(a, mode);
+                                       return a;
+                               }
+                       }
+               }
+       }
+
        return n;
 }