improve value_not_zero

SymConst_addr_ent are never zero for example, also there's no need to
give up after seeing a confirm

diff --git a/ir/opt/opt_confirms.c b/ir/opt/opt_confirms.c
index 817ebe7..dc67eaf 100644 (file)
--- a/ir/opt/opt_confirms.c
+++ b/ir/opt/opt_confirms.c
@@ -120,8 +120,10 @@ int value_not_zero(const ir_node *n, const ir_node **confirm)
                 * without the fear that is might be hidden by a further Confirm.
                 */
                tv = value_of(get_Confirm_bound(n));
-               if (tv == tarval_bad)
-                       return 0;
+               if (tv == tarval_bad) {
+                       n = get_Confirm_value(n);
+                       continue;
+               }
 
                relation = tarval_cmp(tv, get_mode_null(mode));
 
@@ -151,10 +153,13 @@ int value_not_zero(const ir_node *n, const ir_node **confirm)
                }
                n = get_Confirm_value(n);
        }
-       tv = value_of(n);
+       /* global entities are never NULL */
+       if (is_SymConst_addr_ent(n))
+               return true;
 
+       tv = value_of(n);
        if (tv == tarval_bad)
-               return 0;
+               return false;
 
        relation = tarval_cmp(tv, get_mode_null(mode));