avoid dangerous use of memcmp

[libfirm] / ir / opt / ldstopt.c

diff --git a/ir/opt/ldstopt.c b/ir/opt/ldstopt.c
index c1f214c..6d42668 100644 (file)
--- a/ir/opt/ldstopt.c
+++ b/ir/opt/ldstopt.c
@@ -902,8 +902,10 @@ static unsigned follow_Mem_chain_for_Store(ir_node *store, ir_node *curr) {
                } else if (is_Load(pred) && get_Load_ptr(pred) == ptr &&
                           value == pred_info->projs[pn_Load_res]) {
                        /*
-                        * a Store of a value after a Load -- a write after read.
-                        * We may remove the second Store, if it does not have an exception handler.
+                        * a Store of a value just loaded from the same address
+                        * -- a write after read.
+                        * We may remove the Store, if it does not have an exception
+                        * handler.
                         */
                        if (! info->projs[pn_Store_X_except]) {
                                DBG_OPT_WAR(store, pred);
@@ -926,6 +928,12 @@ static unsigned follow_Mem_chain_for_Store(ir_node *store, ir_node *curr) {
                                break;
                        pred = skip_Proj(get_Store_mem(pred));
                } else if (get_irn_op(pred) == op_Load) {
+                       ir_alias_relation rel = get_alias_relation(
+                               current_ir_graph, get_Load_ptr(pred), get_Load_mode(pred),
+                               ptr, mode);
+                       if (rel != no_alias)
+                               break;
+
                        pred = skip_Proj(get_Load_mem(pred));
                } else {
                        /* follow only Load chains */