From d824c60c9643973e0ae9cddc5007b3d9592f8a52 Mon Sep 17 00:00:00 2001
From: Jack Koenig
Date: Wed, 17 May 2017 20:13:26 -0700
Subject: Make sure not to DCE input-only extmodules unless specified (#590)

Fixes #589---
 src/test/scala/firrtlTests/DCETests.scala | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

(limited to 'src/test')

diff --git a/src/test/scala/firrtlTests/DCETests.scala b/src/test/scala/firrtlTests/DCETests.scala
index deb73b3b..129460e1 100644
--- a/src/test/scala/firrtlTests/DCETests.scala
+++ b/src/test/scala/firrtlTests/DCETests.scala
@@ -254,6 +254,29 @@ class DCETests extends FirrtlFlatSpec {
         |    z <= x""".stripMargin
     exec(input, check)
   }
+  "Extmodule with only inputs" should "NOT be deleted by default" in {
+    val input =
+      """circuit Top :
+        |  extmodule InputsOnly :
+        |    input x : UInt<1>
+        |  module Top :
+        |    input x : UInt<1>
+        |    output z : UInt<1>
+        |    inst ext of InputsOnly
+        |    ext.x <= x
+        |    z <= x""".stripMargin
+    val check =
+      """circuit Top :
+        |  extmodule InputsOnly :
+        |    input x : UInt<1>
+        |  module Top :
+        |    input x : UInt<1>
+        |    output z : UInt<1>
+        |    inst ext of InputsOnly
+        |    ext.x <= x
+        |    z <= x""".stripMargin
+    exec(input, check)
+  }
   "Globally dead extmodule marked optimizable" should "be deleted" in {
     val input =
       """circuit Top :
-- 
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