From: Brian Norris <banorris@uci.edu>
Date: Tue, 17 Jul 2012 05:44:40 +0000 (-0700)
Subject: nodestack: re-insert falsely-declared "dead code"
X-Git-Tag: pldi2013~345
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=d86cea5b9a14c8aac805c79422d387ddc8a064b6;p=model-checker.git

nodestack: re-insert falsely-declared "dead code"

"remove dead code...  loop entrance condition is i<backtrack.size().  Therefore,
this branch can never be taken."

False.

While the entrance condition prevents 'i == backtrack.size()', the loop may
exit with 'i == backtrack.size()', since i++ is executed after the last
iteration. Since we do not expect or want this condition to occur, though, I
transform this to a documented ASSERT().
---

diff --git a/nodestack.cc b/nodestack.cc
index 131452d..aa3a6c9 100644
--- a/nodestack.cc
+++ b/nodestack.cc
@@ -109,6 +109,9 @@ thread_id_t Node::get_next_backtrack()
 	for (i = 0; i < backtrack.size(); i++)
 		if (backtrack[i] == true)
 			break;
+	/* Backtrack set was empty? */
+	ASSERT(i != backtrack.size());
+
 	backtrack[i] = false;
 	numBacktracks--;
 	return int_to_id(i);