From: Michael Beck <beck@ipd.info.uni-karlsruhe.de>
Date: Tue, 4 Mar 2008 13:32:09 +0000 (+0000)
Subject: BugFix: when deleting keep-alives of already visited blocks, keep in mind
X-Git-Url: http://nsz.repo.hu/git/?a=commitdiff_plain;h=4be066dfad695f9ed2801882fdd0ad1e82286b78;p=libfirm

BugFix: when deleting keep-alives of already visited blocks, keep in mind
that new keep-alives could be added because the cf was changed ...
So do NOT delete these new KA ...
This fixes segfault4.c

[r17955]
---

diff --git a/ir/ir/irgopt.c b/ir/ir/irgopt.c
index 5ff0ab1ec..26dd09c54 100644
--- a/ir/ir/irgopt.c
+++ b/ir/ir/irgopt.c
@@ -184,7 +184,7 @@ void optimize_graph_df(ir_graph *irg) {
 	pdeq     *waitq = new_pdeq();
 	ir_graph *rem = current_ir_graph;
 	ir_node  *end;
-	int      i, state;
+	int      i, state, n_ka;
 
 	current_ir_graph = irg;
 
@@ -207,13 +207,22 @@ void optimize_graph_df(ir_graph *irg) {
 
 	set_using_irn_link(irg);
 
+	end  = get_irg_end(irg);
+	n_ka = get_End_n_keepalives(end);
+
 	/* 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) {
+	/*
+	 * Optimize keep-alives by removing superfluous ones.
+	 * Beware: the last transformation might add new keep-alives
+	 * that keep blocks that are where visited! So, check only the
+	 * "old" keep-alives, not the new ones!
+	 *
+	 * FIXME: it might be better to completely remove this
+	 * optimization here ...
+	 */
+	for (i = n_ka - 1; i >= 0; --i) {
 		ir_node *ka = get_End_keepalive(end, i);
 
 		if (irn_visited(ka) && !is_irn_keep(ka)) {