Merge pull request #1123 from freechipsproject/dependency-api-2

- Use Dependency API for transform scheduling
- Add tests that old order/behavior is preserved

Or: "Now you're thinking with dependencies."

1 files changed, 13 insertions, 1 deletions

diff --git a/src/main/scala/firrtl/passes/CommonSubexpressionElimination.scala b/src/main/scala/firrtl/passes/CommonSubexpressionElimination.scala
index 3ba12b2d..d54d8088 100644
--- a/src/main/scala/firrtl/passes/CommonSubexpressionElimination.scala
+++ b/src/main/scala/firrtl/passes/CommonSubexpressionElimination.scala
@@ -5,9 +5,21 @@ package firrtl.passes
 import firrtl._
 import firrtl.ir._
 import firrtl.Mappers._
+import firrtl.options.{Dependency, PreservesAll}
 
+object CommonSubexpressionElimination extends Pass with PreservesAll[Transform] {
+
+  override val prerequisites = firrtl.stage.Forms.LowForm ++
+    Seq( Dependency(firrtl.passes.RemoveValidIf),
+         Dependency[firrtl.transforms.ConstantPropagation],
+         Dependency(firrtl.passes.memlib.VerilogMemDelays),
+         Dependency(firrtl.passes.SplitExpressions),
+         Dependency[firrtl.transforms.CombineCats] )
+
+  override val dependents =
+    Seq( Dependency[SystemVerilogEmitter],
+         Dependency[VerilogEmitter] )
 
-object CommonSubexpressionElimination extends Pass {
   private def cse(s: Statement): Statement = {
     val expressions = collection.mutable.HashMap[MemoizedHash[Expression], String]()
     val nodes = collection.mutable.HashMap[String, Expression]()