1 files changed, 50 insertions, 0 deletions
diff --git a/src/test/scala/firrtlTests/analyses/CircuitGraphSpec.scala b/src/test/scala/firrtlTests/analyses/CircuitGraphSpec.scala
new file mode 100644
index 00000000..79922fa9
--- /dev/null
+++ b/src/test/scala/firrtlTests/analyses/CircuitGraphSpec.scala
@@ -0,0 +1,50 @@
+// See LICENSE for license details.
+
+package firrtlTests.analyses
+
+import firrtl.analyses.CircuitGraph
+import firrtl.annotations.CircuitTarget
+import firrtl.options.Dependency
+import firrtl.passes.ExpandWhensAndCheck
+import firrtl.stage.{Forms, TransformManager}
+import firrtl.testutils.FirrtlFlatSpec
+import firrtl.{ChirrtlForm, CircuitState, FileUtils, UnknownForm}
+
+class CircuitGraphSpec extends FirrtlFlatSpec {
+    "CircuitGraph" should "find paths with deep hierarchy quickly" in {
+      def mkChild(n: Int): String =
+        s"""  module Child${n} :
+           |    input in: UInt<8>
+           |    output out: UInt<8>
+           |    inst c1 of Child${n+1}
+           |    inst c2 of Child${n+1}
+           |    c1.in <= in
+           |    c2.in <= c1.out
+           |    out <= c2.out
+         """.stripMargin
+      def mkLeaf(n: Int): String =
+        s"""  module Child${n} :
+           |    input in: UInt<8>
+           |    output out: UInt<8>
+           |    wire middle: UInt<8>
+           |    middle <= in
+           |    out <= middle
+         """.stripMargin
+      (2 until 23 by 2).foreach { n =>
+        val input = new StringBuilder()
+        input ++=
+          """circuit Child0:
+            |""".stripMargin
+        (0 until n).foreach { i => input ++= mkChild(i); input ++= "\n" }
+        input ++= mkLeaf(n)
+        val circuit = new firrtl.stage.transforms.Compiler(Seq(Dependency[ExpandWhensAndCheck])).runTransform(
+          CircuitState(parse(input.toString()), UnknownForm)
+        ).circuit
+        val circuitGraph = CircuitGraph(circuit)
+        val C = CircuitTarget("Child0")
+        val Child0 = C.module("Child0")
+        circuitGraph.connectionPath(Child0.ref("in"), Child0.ref("out"))
+      }
+    }
+
+}