Don't look back past the CSourcePath supported length

matdb/mat/paths.cpp

@@ -100,22 +100,30 @@ inline CSourcePath path_append_front(const CSourcePath& inPath, CellID idx)
 CellID bidirDepthFirstSearch(threadDB* thread_db, CSourcePath partialPath, CellID bestLGIdx = CellID(-1))
 {
 	// Get backward-looking edges from start of path
-	int lEdgeCount = gccInEdges.count(partialPath.peek_front());
+	int lEdgeCount = 0;
+	if (partialPath.startIdx > 0)
+	{
+		lEdgeCount = gccInEdges.count(partialPath.peek_front());
 		if (lEdgeCount > 0)
 		{
 			for (CellID leftID : gccInEdges[partialPath.peek_front()])
 			{
-			bestLGIdx = bidirDepthFirstSearch(thread_db, path_append_back(partialPath, leftID), bestLGIdx);
+				bestLGIdx = bidirDepthFirstSearch(thread_db, path_append_front(partialPath, leftID), bestLGIdx);
+			}
 		}
 	}
 
 	// Get forward-looking edges from end of path
-	int rEdgeCount = gccOutEdges.count(partialPath.peek_back());
+	int rEdgeCount = 0;
+	if (partialPath.endIdx < partialPath.indices.size() - 1)
+	{
+		rEdgeCount = gccOutEdges.count(partialPath.peek_back());
 		if (rEdgeCount > 0)
 		{
 			for (CellID rightID : gccOutEdges[partialPath.peek_back()])
 			{
-			bestLGIdx = bidirDepthFirstSearch(thread_db, path_append_front(partialPath, rightID), bestLGIdx);
+				bestLGIdx = bidirDepthFirstSearch(thread_db, path_append_back(partialPath, rightID), bestLGIdx);
+			}
 		}
 	}