Convert PreservesAll to explicit invalidates=false

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

1 files changed, 4 insertions, 2 deletions

diff --git a/src/main/scala/firrtl/passes/CommonSubexpressionElimination.scala b/src/main/scala/firrtl/passes/CommonSubexpressionElimination.scala
index 567cf5f1..544f90a6 100644
--- a/src/main/scala/firrtl/passes/CommonSubexpressionElimination.scala
+++ b/src/main/scala/firrtl/passes/CommonSubexpressionElimination.scala
@@ -5,9 +5,9 @@ package firrtl.passes
 import firrtl._
 import firrtl.ir._
 import firrtl.Mappers._
-import firrtl.options.{Dependency, PreservesAll}
+import firrtl.options.Dependency
 
-object CommonSubexpressionElimination extends Pass with PreservesAll[Transform] {
+object CommonSubexpressionElimination extends Pass {
 
   override def prerequisites = firrtl.stage.Forms.LowForm ++
     Seq( Dependency(firrtl.passes.RemoveValidIf),
@@ -20,6 +20,8 @@ object CommonSubexpressionElimination extends Pass with PreservesAll[Transform]
     Seq( Dependency[SystemVerilogEmitter],
          Dependency[VerilogEmitter] )
 
+  override def invalidates(a: Transform) = false
+
   private def cse(s: Statement): Statement = {
     val expressions = collection.mutable.HashMap[MemoizedHash[Expression], String]()
     val nodes = collection.mutable.HashMap[String, Expression]()