Optimization: use AnyRef map for Namer -> Typer tree handoff

And uses a map per-compilation unit, rather than one per Typer.

One small change required: we now need to clear this map in the
the interactive compiler which reuses compilation units, rather
than in the call to `Typer#reset`.

1 files changed, 4 insertions, 3 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index 101e1526fe..074f8df303 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -13,7 +13,7 @@ package scala
 package tools.nsc
 package typechecker
 
-import scala.collection.{ mutable, immutable }
+import scala.collection.{mutable, immutable}
 import scala.reflect.internal.util.{ BatchSourceFile, Statistics, shortClassOfInstance }
 import mutable.ListBuffer
 import symtab.Flags._
@@ -39,7 +39,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
   // namer calls typer.computeType(rhs) on DefDef / ValDef when tpt is empty. the result
   // is cached here and re-used in typedDefDef / typedValDef
   // Also used to cache imports type-checked by namer.
-  val transformed = new mutable.HashMap[Tree, Tree]
+  val transformed = new mutable.AnyRefMap[Tree, Tree]
 
   final val shortenImports = false
 
@@ -52,7 +52,6 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
     //println("resetTyper called")
     resetContexts()
     resetImplicits()
-    transformed.clear()
     resetDocComments()
   }
 
@@ -108,6 +107,8 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
     val runDefinitions = currentRun.runDefinitions
     import runDefinitions._
 
+    private val transformed: mutable.Map[Tree, Tree] = unit.transformed
+
     val infer = new Inferencer(context0) {
       // See SI-3281 re undoLog
       override def isCoercible(tp: Type, pt: Type) = undoLog undo viewExists(tp, pt)