fix

[libfirm] / ir / ir / irgopt.c

diff --git a/ir/ir/irgopt.c b/ir/ir/irgopt.c
index dc0df8d..8a7dde8 100644 (file)
--- a/ir/ir/irgopt.c
+++ b/ir/ir/irgopt.c
@@ -178,6 +178,8 @@ void optimize_graph_df(ir_graph *irg) {
        pdeq     *waitq = new_pdeq();
        int      state = edges_activated(irg);
        ir_graph *rem = current_ir_graph;
+       ir_node  *end;
+       int      i;
 
        current_ir_graph = irg;
 
@@ -201,8 +203,23 @@ void optimize_graph_df(ir_graph *irg) {
 
        set_using_irn_link(irg);
 
-       /* walk over the graph */
-       irg_walk_graph(irg, NULL, opt_walker, waitq);
+       /* walk over the graph, but don't touch keep-alives */
+       irg_walk(get_irg_end_block(irg), NULL, opt_walker, waitq);
+
+       end = get_irg_end(irg);
+
+       /* optimize keep-alives by removing superfluous ones */
+       for (i = get_End_n_keepalives(end) - 1; i >= 0; --i) {
+               ir_node *ka = get_End_keepalive(end, i);
+
+               if (irn_visited(ka) && !is_irn_keep(ka)) {
+                       /* this node can be regularly visited, no need to keep it */
+                       set_End_keepalive(end, i, get_irg_bad(irg));
+               }
+       }
+       /* now walk again and visit all not yet visited nodes */
+       set_irg_visited(current_ir_graph, get_irg_visited(irg) - 1);
+       irg_walk(get_irg_end(irg), NULL, opt_walker, waitq);
 
        /* finish the wait queue */
        while (! pdeq_empty(waitq)) {