Added RemoveEmpty.scala, which removes Empty and nested Blocks (#218)

* Added RemoveEmpty.scala, which removes Empty and nested Blocks

* Reused squashEmpty from ExpandWhens by moving it to Utils

* Squash EmptyStmts in ExpandWhens correctly

1 files changed, 19 insertions, 0 deletions

diff --git a/src/main/scala/firrtl/passes/RemoveEmpty.scala b/src/main/scala/firrtl/passes/RemoveEmpty.scala
new file mode 100644
index 00000000..e765d1f4
--- /dev/null
+++ b/src/main/scala/firrtl/passes/RemoveEmpty.scala
@@ -0,0 +1,19 @@
+package firrtl
+package passes
+
+import scala.collection.mutable
+import firrtl.Mappers.{ExpMap, StmtMap}
+import firrtl.ir._
+
+object RemoveEmpty extends Pass {
+  def name = "Remove Empty Statements"
+  private def onModule(m: DefModule): DefModule = {
+    m match {
+      case m: Module => Module(m.info, m.name, m.ports, Utils.squashEmpty(m.body))
+      case m: ExtModule => m
+    }
+  }
+  def run(c: Circuit): Circuit = Circuit(c.info, c.modules.map(onModule _), c.main)
+}
+
+// vim: set ts=4 sw=4 et: