Change annotation logging (#1461)

* Change from log-level debug to trace
* Serialize as JSON rather than .serialize on each annotation

Co-Authored-By: Chick Markley <chick@qrhino.com>

src/main/scala/firrtl/Compiler.scala

@@ -295,10 +295,8 @@ trait Transform extends TransformLike[CircuitState] with DependencyAPI[Transform
     val remappedAnnotations = propagateAnnotations(state.annotations, result.annotations, result.renames)
 
     logger.info(s"Form: ${result.form}")
-    logger.debug(s"Annotations:")
-    remappedAnnotations.foreach { a =>
-      logger.debug(a.serialize)
-    }
+    logger.trace(s"Annotations:")
+    logger.trace(JsonProtocol.serialize(remappedAnnotations))
     logger.trace(s"Circuit:\n${result.circuit.serialize}")
     logger.info(s"======== Finished Transform $name ========\n")
     CircuitState(result.circuit, result.form, remappedAnnotations, None)

src/main/scala/firrtl/annotations/Annotation.scala

@@ -14,9 +14,9 @@ trait Annotation extends Product {
   /** Update the target based on how signals are renamed */
   def update(renames: RenameMap): Seq[Annotation]
 
-  /** Pretty Print
+  /** Optional pretty print
     *
-    * @note In [[logger.LogLevel.Debug]] this is called on every Annotation after every Transform
+    * @note rarely used
     */
   def serialize: String = this.toString
 

src/main/scala/firrtl/stage/transforms/UpdateAnnotations.scala

@@ -3,7 +3,7 @@
 package firrtl.stage.transforms
 
 import firrtl.{AnnotationSeq, CircuitState, RenameMap, Transform, Utils}
-import firrtl.annotations.{Annotation, DeletedAnnotation}
+import firrtl.annotations.{Annotation, DeletedAnnotation, JsonProtocol}
 import firrtl.options.Translator
 
 import scala.collection.mutable
@@ -21,9 +21,8 @@ class UpdateAnnotations(val underlying: Transform) extends Transform with Wrappe
     val remappedAnnotations = propagateAnnotations(state.annotations, result.annotations, result.renames)
 
     logger.info(s"Form: ${result.form}")
-
-    logger.debug(s"Annotations:")
-    remappedAnnotations.foreach( a => logger.debug(a.serialize) )
+    logger.trace(s"Annotations:")
+    logger.trace(JsonProtocol.serialize(remappedAnnotations))
 
     logger.trace(s"Circuit:\n${result.circuit.serialize}")
     logger.info(s"======== Finished Transform $name ========\n")