1 files changed, 22 insertions, 2 deletions
diff --git a/src/main/scala/firrtl/transforms/ConstantPropagation.scala b/src/main/scala/firrtl/transforms/ConstantPropagation.scala
index da7f1a46..8a273476 100644
--- a/src/main/scala/firrtl/transforms/ConstantPropagation.scala
+++ b/src/main/scala/firrtl/transforms/ConstantPropagation.scala
@@ -67,7 +67,7 @@ class ConstantPropagation extends Transform with ResolvedAnnotationPaths {
   }
 
   object FoldADD extends FoldCommutativeOp {
-    def fold(c1: Literal, c2: Literal) = (c1, c2) match {
+    def fold(c1: Literal, c2: Literal) = ((c1, c2): @unchecked) match {
       case (_: UIntLiteral, _: UIntLiteral) => UIntLiteral(c1.value + c2.value, (c1.width max c2.width) + IntWidth(1))
       case (_: SIntLiteral, _: SIntLiteral) => SIntLiteral(c1.value + c2.value, (c1.width max c2.width) + IntWidth(1))
     }
@@ -137,6 +137,13 @@ class ConstantPropagation extends Transform with ResolvedAnnotationPaths {
     }
   }
 
+  private def foldDynamicShiftLeft(e: DoPrim) = e.args.last match {
+    case UIntLiteral(v, IntWidth(w)) =>
+      val shl = DoPrim(Shl, Seq(e.args.head), Seq(v), UnknownType)
+      pad(PrimOps.set_primop_type(shl), e.tpe)
+    case _ => e
+  }
+
   private def foldShiftRight(e: DoPrim) = e.consts.head.toInt match {
     case 0 => e.args.head
     case x => e.args.head match {
@@ -148,6 +155,14 @@ class ConstantPropagation extends Transform with ResolvedAnnotationPaths {
     }
   }
 
+  private def foldDynamicShiftRight(e: DoPrim) = e.args.last match {
+    case UIntLiteral(v, IntWidth(w)) =>
+      val shr = DoPrim(Shr, Seq(e.args.head), Seq(v), UnknownType)
+      pad(PrimOps.set_primop_type(shr), e.tpe)
+    case _ => e
+  }
+
+
   private def foldComparison(e: DoPrim) = {
     def foldIfZeroedArg(x: Expression): Expression = {
       def isUInt(e: Expression): Boolean = e.tpe match {
@@ -221,7 +236,9 @@ class ConstantPropagation extends Transform with ResolvedAnnotationPaths {
 
   private def constPropPrim(e: DoPrim): Expression = e.op match {
     case Shl => foldShiftLeft(e)
+    case Dshl => foldDynamicShiftLeft(e)
     case Shr => foldShiftRight(e)
+    case Dshr => foldDynamicShiftRight(e)
     case Cat => foldConcat(e)
     case Add => FoldADD(e)
     case And => FoldAND(e)
@@ -277,6 +294,7 @@ class ConstantPropagation extends Transform with ResolvedAnnotationPaths {
 
   def optimize(e: Expression): Expression = constPropExpression(new NodeMap(), Map.empty[String, String], Map.empty[String, Map[String, Literal]])(e)
   def optimize(e: Expression, nodeMap: NodeMap): Expression = constPropExpression(nodeMap, Map.empty[String, String], Map.empty[String, Map[String, Literal]])(e)
+
   private def constPropExpression(nodeMap: NodeMap, instMap: Map[String, String], constSubOutputs: Map[String, Map[String, Literal]])(e: Expression): Expression = {
     val old = e map constPropExpression(nodeMap, instMap, constSubOutputs)
     val propagated = old match {
@@ -290,7 +308,9 @@ class ConstantPropagation extends Transform with ResolvedAnnotationPaths {
         constSubOutputs.get(module).flatMap(_.get(pname)).getOrElse(ref)
       case x => x
     }
-    propagated
+    // We're done when the Expression no longer changes
+    if (propagated eq old) propagated
+    else constPropExpression(nodeMap, instMap, constSubOutputs)(propagated)
   }
 
   /** Constant propagate a Module