Add auto clone implementation for inner Bundles (#722)

2 files changed, 32 insertions, 0 deletions

diff --git a/chiselFrontend/src/main/scala/chisel3/core/Aggregate.scala b/chiselFrontend/src/main/scala/chisel3/core/Aggregate.scala
index d4d67018..da14cefd 100644
--- a/chiselFrontend/src/main/scala/chisel3/core/Aggregate.scala
+++ b/chiselFrontend/src/main/scala/chisel3/core/Aggregate.scala
@@ -5,6 +5,7 @@ package chisel3.core
 import scala.collection.immutable.ListMap
 import scala.collection.mutable.{ArrayBuffer, HashSet, LinkedHashMap}
 import scala.language.experimental.macros
+import scala.util.Try
 
 import chisel3.internal._
 import chisel3.internal.Builder.pushCommand
@@ -574,6 +575,30 @@ class Bundle(implicit compileOptions: CompileOptions) extends Record {
       Builder.exception(s"Unable to automatically infer cloneType on $this: $desc")
     }
 
+    // Check if the bundle is an instance of an inner class by examining
+    // whether it has one one-argument constructor taking a type matching the enclosing class
+    if (this.getClass.getConstructors.size == 1) {
+      val aggClass = this.getClass
+      val constr = aggClass.getConstructors.head
+      val argTypes = constr.getParameterTypes
+      val outerClass = aggClass.getEnclosingClass
+      if (argTypes.size == 1 && outerClass != null) {
+        // attempt to clone using "$outer"
+        var clone: Option[this.type] =
+          Try[this.type](constr.newInstance(aggClass.getDeclaredField("$outer").get(this)).asInstanceOf[this.type]).toOption
+        if (clone.isEmpty) {
+          // fall back to outerModule field
+          clone = Try[this.type](constr.newInstance(outerModule.get).asInstanceOf[this.type]).toOption
+        }
+        clone.foreach(_.outerModule = this.outerModule)
+        if (clone.isDefined) {
+          return clone.get
+        } else {
+          reflectError("non-trivial inner Bundle class")
+        }
+      }
+    }
+
     // Try Scala reflection
     import scala.reflect.runtime.universe._
 
diff --git a/chiselFrontend/src/main/scala/chisel3/core/Data.scala b/chiselFrontend/src/main/scala/chisel3/core/Data.scala
index 19adf01b..d84a86e9 100644
--- a/chiselFrontend/src/main/scala/chisel3/core/Data.scala
+++ b/chiselFrontend/src/main/scala/chisel3/core/Data.scala
@@ -208,6 +208,13 @@ abstract class Data extends HasId {
     }
   }
 
+  // If this Data is an instance of an inner class, record enclosing class
+  // This is only used for cloneType!
+  private[core] var outerModule: Option[BaseModule] =
+    (Option(this.getClass.getEnclosingClass) zip Builder.currentModule)
+      .find({ case (c, m) => c.isAssignableFrom(m.getClass) })
+      .map({ case (_, m) => m })
+
   // User-specified direction, local at this node only.
   // Note that the actual direction of this node can differ from child and parent specifiedDirection.
   private var _specifiedDirection: SpecifiedDirection = SpecifiedDirection.Unspecified