Cleanup Named Targets (#1311)

* Add CleanupNamedTargets Transform

Adds a new transform, CleanupNamedTargets, that will convert
ReferenceTargets to InstanceTargets if any ReferenceTargets are found
to be actually pointing at instances.

This fixes an issue where a ComponentName pointing at an instance will
be converted to a ReferenceTarget. Later on, this ReferenceTarget will
not be properly renamed by other transforms, e.g.,
EliminateTargetPaths.

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

* Update ScalaTests

Co-authored-by: Jack Koenig <koenig@sifive.com>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

2 files changed, 68 insertions, 1 deletions

diff --git a/src/main/scala/firrtl/annotations/transforms/CleanupNamedTargets.scala b/src/main/scala/firrtl/annotations/transforms/CleanupNamedTargets.scala
new file mode 100644
index 00000000..a4219a03
--- /dev/null
+++ b/src/main/scala/firrtl/annotations/transforms/CleanupNamedTargets.scala
@@ -0,0 +1,66 @@
+// See LICENSE for license details.
+
+package firrtl.annotations.transforms
+
+import firrtl._
+import firrtl.annotations.{CircuitTarget, ModuleTarget, MultiTargetAnnotation, ReferenceTarget, SingleTargetAnnotation}
+import firrtl.ir
+import firrtl.options.{Dependency, PreservesAll}
+import firrtl.traversals.Foreachers._
+
+import scala.collection.immutable.{Set => ISet}
+
+/** Replaces all [[firrtl.annotations.ReferenceTarget ReferenceTargets]] pointing at instances with
+  * [[firrtl.annotations.InstanceTarget InstanceTargets]].
+  *
+  * @note This exists because of [[firrtl.annotations.Named Named]] where a [[firrtl.annotations.ComponentName
+  * ComponentName]] is the only way to refer to an instance, but this is resolved incorrectly to a
+  * [[firrtl.annotations.ReferenceTarget ReferenceTarget]].
+  */
+class CleanupNamedTargets extends Transform with DependencyAPIMigration {
+
+  override def prerequisites = Seq(Dependency(passes.RemoveCHIRRTL))
+
+  override def optionalPrerequisites = Seq.empty
+
+  override def optionalPrerequisiteOf = Seq.empty
+
+  override def invalidates(a: Transform) = false
+
+  private def onStatement(statement: ir.Statement)
+                         (implicit references: ISet[ReferenceTarget],
+                          renameMap: RenameMap,
+                          module: ModuleTarget): Unit = statement match {
+    case ir.DefInstance(_, a, b, _) if references(module.instOf(a, b).asReference) =>
+      renameMap.record(module.instOf(a, b).asReference, module.instOf(a, b))
+    case a => statement.foreach(onStatement)
+  }
+
+  private def onModule(module: ir.DefModule)
+                      (implicit references: ISet[ReferenceTarget],
+                       renameMap: RenameMap,
+                       circuit: CircuitTarget): Unit = {
+    implicit val mTarget = circuit.module(module.name)
+    module.foreach(onStatement)
+  }
+
+  override protected def execute(state: CircuitState): CircuitState = {
+
+    implicit val rTargets: ISet[ReferenceTarget] = state.annotations.flatMap {
+      case a: SingleTargetAnnotation[_] => Some(a.target)
+      case a: MultiTargetAnnotation     => a.targets.flatten
+      case _                            => None
+    }.collect {
+      case a: ReferenceTarget => a
+    }.toSet
+
+    implicit val renameMap = RenameMap()
+
+    implicit val cTarget = CircuitTarget(state.circuit.main)
+
+    state.circuit.foreach(onModule)
+
+    state.copy(renames = Some(renameMap))
+  }
+
+}
diff --git a/src/main/scala/firrtl/stage/Forms.scala b/src/main/scala/firrtl/stage/Forms.scala
index 55292fc5..636d0609 100644
--- a/src/main/scala/firrtl/stage/Forms.scala
+++ b/src/main/scala/firrtl/stage/Forms.scala
@@ -20,7 +20,8 @@ object Forms {
     Seq( Dependency(passes.CheckChirrtl),
          Dependency(passes.CInferTypes),
          Dependency(passes.CInferMDir),
-         Dependency(passes.RemoveCHIRRTL) )
+         Dependency(passes.RemoveCHIRRTL),
+         Dependency[annotations.transforms.CleanupNamedTargets] )
 
   val WorkingIR: Seq[TransformDependency] = MinimalHighForm :+ Dependency(passes.ToWorkingIR)