Cache identifier search in trees

Author: odersky

compiler/src/dotty/tools/dotc/core/Decorators.scala

@@ -201,5 +201,9 @@ object Decorators {
     def hl(args: Any*)(implicit ctx: Context): String =
       new SyntaxFormatter(sc).assemble(args).stripMargin
   }
+
+  implicit class ArrayInterpolator[T <: AnyRef](val arr: Array[T]) extends AnyVal {
+    def binarySearch(x: T): Int = java.util.Arrays.binarySearch(arr.asInstanceOf[Array[Object]], x)
+  }
 }
 

compiler/src/dotty/tools/dotc/core/Symbols.scala

@@ -21,15 +21,15 @@ import StdNames._
 import NameOps._
 import NameKinds.LazyImplicitName
 import ast.tpd
-import tpd.{Tree, TreeProvider}
+import tpd.{Tree, TreeProvider, TreeOps}
 import ast.TreeTypeMap
 import Constants.Constant
 import reporting.diagnostic.Message
 import Denotations.{ Denotation, SingleDenotation, MultiDenotation }
 import collection.mutable
 import io.AbstractFile
 import language.implicitConversions
-import util.{NoSource, DotClass}
+import util.{NoSource, DotClass, Property}
 import scala.collection.JavaConverters._
 
 /** Creation methods for symbols */
@@ -402,6 +402,9 @@ object Symbols {
 
   implicit def eqSymbol: Eq[Symbol, Symbol] = Eq
 
+  /** Tree attachment containing the identifiers in a tree as a sorted array */
+  val Ids = new Property.Key[Array[String]]
+
   /** A Symbol represents a Scala definition/declaration or a package.
    *  @param coord  The coordinates of the symbol (a position or an index)
    *  @param id     A unique identifier of the symbol (unique per ContextBase)
@@ -654,7 +657,7 @@ object Symbols {
             }
             else tpd.EmptyTree
           case tree: Tree @ unchecked =>
-            tree
+            if (id.isEmpty || mightContain(tree, id)) tree else tpd.EmptyTree
         }
     }
 
@@ -663,6 +666,22 @@ object Symbols {
     private[dotc] def treeOrProvider_=(t: TreeOrProvider)(implicit ctx: Context): Unit =
       myTree = t
 
+    private def mightContain(tree: Tree, id: String)(implicit ctx: Context): Boolean = {
+      val ids = tree.getAttachment(Ids) match {
+        case Some(ids) => ids
+        case None =>
+          val idSet = mutable.SortedSet[String]()
+          tree.foreachSubTree {
+            case tree: tpd.RefTree => idSet += tree.name.toString
+            case _ =>
+          }
+          val ids = idSet.toArray
+          tree.putAttachment(Ids, ids)
+          ids
+      }
+      ids.binarySearch(id) >= 0
+    }
+
     /** The source or class file from which this class was generated, null if not applicable. */
     override def associatedFile(implicit ctx: Context): AbstractFile =
       if (assocFile != null || (this.owner is PackageClass) || this.isEffectiveRoot) assocFile

compiler/src/dotty/tools/dotc/core/tasty/DottyUnpickler.scala

@@ -3,13 +3,12 @@ package dotc
 package core
 package tasty
 
-import Contexts._, SymDenotations._, Symbols._
+import Contexts._, SymDenotations._, Symbols._,  Decorators._
 import dotty.tools.dotc.ast.tpd
 import TastyUnpickler._, TastyBuffer._
 import util.Positions._
 import util.{SourceFile, NoSource}
 import Annotations.Annotation
-import core.Mode
 import classfile.ClassfileParser
 
 object DottyUnpickler {
@@ -56,6 +55,6 @@ class DottyUnpickler(bytes: Array[Byte]) extends ClassfileParser.Embedded with t
 
   override def mightContain(id: String)(implicit ctx: Context): Boolean = {
     if (ids == null) ids = unpickler.nameAtRef.contents.toArray.map(_.toString).sorted
-    java.util.Arrays.binarySearch(ids.asInstanceOf[Array[Object]], id) >= 0
+    ids.binarySearch(id) >= 0
   }
 }