Make pathsInDAG walk all possible paths (#655)

* Make pathsInDAG walk all possible paths

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@ibm.com>

* Use linearization order when finding all paths in DAG

1 files changed, 3 insertions, 7 deletions

diff --git a/src/main/scala/firrtl/graph/DiGraph.scala b/src/main/scala/firrtl/graph/DiGraph.scala
index ee00789e..39016732 100644
--- a/src/main/scala/firrtl/graph/DiGraph.scala
+++ b/src/main/scala/firrtl/graph/DiGraph.scala
@@ -273,17 +273,13 @@ class DiGraph[T] (val edges: Map[T, Set[T]]) extends DiGraphLike[T] {
     // paths(v) holds the set of paths from start to v
     val paths = new mutable.HashMap[T,mutable.Set[Seq[T]]] with mutable.MultiMap[T,Seq[T]]
     val queue = new mutable.Queue[T]
-    val visited = new mutable.HashSet[T]
+    val reachable = reachableFrom(start)
     paths.addBinding(start,Seq(start))
-    queue.enqueue(start)
-    visited += start
+    queue += start
+    queue ++= linearize.filter(reachable.contains(_))
     while (!queue.isEmpty) {
       val current = queue.dequeue
       for (v <- getEdges(current)) {
-        if (!visited.contains(v)) {
-          queue.enqueue(v)
-          visited += v
-        }
         for (p <- paths(current)) {
           paths.addBinding(v, p :+ v)
         }