Cmp(Conv(x), 0) -> Cmp(x, 0) if dest mode ist wider than source mode.

[r15829]

diff --git a/ir/ir/iropt.c b/ir/ir/iropt.c
index c6c052f..26299c0 100644 (file)
--- a/ir/ir/iropt.c
+++ b/ir/ir/iropt.c
@@ -3432,6 +3432,24 @@ static ir_node *transform_node_Proj_Cmp(ir_node *proj) {
                }
        }
 
+       /* TODO extend to arbitrary constants */
+       if (is_Conv(left) &&
+                       is_Const(right) &&
+                       tarval_is_null(get_Const_tarval(right))) {
+               ir_mode* mode    = get_irn_mode(left);
+               ir_node* op      = get_Conv_op(left);
+               ir_mode* op_mode = get_irn_mode(op);
+
+               if (get_mode_size_bits(mode) > get_mode_size_bits(op_mode) &&
+                               (mode_is_signed(mode) || !mode_is_signed(op_mode))) {
+                       ir_node  *null  = new_Const(op_mode, get_mode_null(op_mode));
+                       dbg_info *dbg   = get_irn_dbg_info(n);
+                       ir_graph *irg   = current_ir_graph;
+                       ir_node  *block = get_nodes_block(n);
+                       return new_rd_Cmp(dbg, irg, block, op, null);
+               }
+       }
+
        /* remove Casts */
        if (is_Cast(left))
                left = get_Cast_op(left);
@@ -3511,7 +3529,6 @@ static ir_node *transform_node_Proj_Cmp(ir_node *proj) {
                        default:
                                break;
                        }
-
                }
        }