Some changes in the interest of speedups.

9 files changed, 89 insertions, 73 deletions

diff --git a/src/dotty/tools/dotc/ast/tpd.scala b/src/dotty/tools/dotc/ast/tpd.scala
index 77983830c..a8da15bd7 100644
--- a/src/dotty/tools/dotc/ast/tpd.scala
+++ b/src/dotty/tools/dotc/ast/tpd.scala
@@ -108,12 +108,12 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
       def apply(tp: Type) = tp match {
         case tp: TermRef if toAvoid(tp) && variance > 0 =>
           apply(tp.info)
-        case tp @ TypeRef(pre, _) if toAvoid(pre) =>
+        case tp: TypeRef if toAvoid(tp.prefix) =>
           tp.info match {
             case TypeAlias(ref) => apply(ref)
             case _ => mapOver(tp)
           }
-        case tp @ RefinedType(parent, _) =>
+        case tp: RefinedType =>
           val tp1 @ RefinedType(parent1, _) = mapOver(tp)
           if (tp1.refinedInfo existsPart toAvoid) {
             typr.println(s"dropping refinement from $tp1")
diff --git a/src/dotty/tools/dotc/core/Denotations.scala b/src/dotty/tools/dotc/core/Denotations.scala
index 5ca53b04e..1e4d0f47a 100644
--- a/src/dotty/tools/dotc/core/Denotations.scala
+++ b/src/dotty/tools/dotc/core/Denotations.scala
@@ -769,6 +769,7 @@ object Denotations {
 
   /** An exception for accessing symbols that are no longer valid in current run */
   class StaleSymbol(msg: => String) extends Exception {
+    util.Stats.record("stale symbol")
     override def getMessage() = msg
   }
 }
diff --git a/src/dotty/tools/dotc/core/TypeOps.scala b/src/dotty/tools/dotc/core/TypeOps.scala
index 1a782ac63..6e984e43c 100644
--- a/src/dotty/tools/dotc/core/TypeOps.scala
+++ b/src/dotty/tools/dotc/core/TypeOps.scala
@@ -47,6 +47,28 @@ trait TypeOps { this: Context =>
     def apply(tp: Type) = asSeenFrom(tp, pre, cls, this)
   }
 
+  /** Implementation of Types#simplified */
+  final def simplify(tp: Type, theMap: SimplifyMap): Type = tp match {
+    case tp: NamedType =>
+      tp.derivedSelect(simplify(tp.prefix, theMap))
+    case  _: ThisType | NoPrefix =>
+      tp
+    case tp: RefinedType =>
+      tp.derivedRefinedType(simplify(tp.parent, theMap), tp.refinedName, simplify(tp.refinedInfo, theMap))
+    case AndType(l, r) =>
+      simplify(l, theMap) & simplify(r, theMap)
+    case OrType(l, r) =>
+      simplify(l, theMap) | simplify(r, theMap)
+    case tp: PolyParam =>
+      typerState.constraint.typeVarOfParam(tp) orElse tp
+    case _ =>
+      (if (theMap != null) theMap else new SimplifyMap).mapOver(tp)
+  }
+
+  class SimplifyMap extends TypeMap {
+    def apply(tp: Type) = simplify(tp, this)
+  }
+
   final def isVolatile(tp: Type): Boolean = {
     /** Pre-filter to avoid expensive DNF computation */
     def needsChecking(tp: Type, isPart: Boolean): Boolean = tp match {
diff --git a/src/dotty/tools/dotc/core/Types.scala b/src/dotty/tools/dotc/core/Types.scala
index 71218680a..b99162383 100644
--- a/src/dotty/tools/dotc/core/Types.scala
+++ b/src/dotty/tools/dotc/core/Types.scala
@@ -26,6 +26,7 @@ import Uniques._
 import collection.{mutable, Seq, breakOut}
 import config.Config
 import config.Printers._
+import annotation.tailrec
 import language.implicitConversions
 
 object Types {
@@ -342,45 +343,52 @@ object Types {
      *  flags in `excluded` from consideration.
      */
     final def findMember(name: Name, pre: Type, excluded: FlagSet)(implicit ctx: Context): Denotation = try {
-      this match {
+      @tailrec def go(tp: Type): Denotation = tp match {
         case tp: RefinedType =>
-          val pdenot = tp.parent.findMember(name, pre, excluded)
-          if (name eq tp.refinedName) {
-            val rinfo = tp.refinedInfo.substThis(tp, pre)
-            if (name.isTypeName) // simplified case that runs more efficiently
-              pdenot.asSingleDenotation.derivedSingleDenotation(pdenot.symbol, rinfo)
-            else
-              pdenot & (new JointRefDenotation(NoSymbol, rinfo, Period.allInRun(ctx.runId)), pre)
-          } else pdenot
+          if (name eq tp.refinedName) goRefined(tp) else go(tp.parent)
         case tp: ThisType =>
-          val d = tp.underlying.findMember(name, pre, excluded)
-          if (d.exists) d
-          else
-            // There is a special case to handle:
-            //   trait Super { this: Sub => private class Inner {} println(this.Inner) }
-            //   class Sub extends Super
-            // When resolving Super.this.Inner, the normal logic goes to the self type and
-            // looks for Inner from there. But this fails because Inner is private.
-            // We fix the problem by having the following fallback case, which links up the
-            // member in Super instead of Sub.
-            // As an example of this in the wild, see
-            // loadClassWithPrivateInnerAndSubSelf in ShowClassTests
-            tp.cls.typeRef.findMember(name, pre, excluded) orElse d
+          goThis(tp)
         case tp: TypeRef =>
           tp.denot.findMember(name, pre, excluded)
         case tp: TypeProxy =>
-          tp.underlying.findMember(name, pre, excluded)
+          go(tp.underlying)
         case tp: ClassInfo =>
           tp.cls.findMember(name, pre, excluded)
         case AndType(l, r) =>
-          l.findMember(name, pre, excluded) & (r.findMember(name, pre, excluded), pre)
+          goAnd(l, r)
         case OrType(l, r) =>
-          l.findMember(name, pre, excluded) | (r.findMember(name, pre, excluded), pre)
+          goOr(l, r)
         case ErrorType =>
           ctx.newErrorSymbol(pre.classSymbol orElse defn.RootClass, name)
         case _ =>
           NoDenotation
       }
+      def goRefined(tp: RefinedType) = {
+        val pdenot = go(tp.parent)
+        val rinfo = tp.refinedInfo.substThis(tp, pre)
+        if (name.isTypeName) // simplified case that runs more efficiently
+          pdenot.asSingleDenotation.derivedSingleDenotation(pdenot.symbol, rinfo)
+        else
+          pdenot & (new JointRefDenotation(NoSymbol, rinfo, Period.allInRun(ctx.runId)), pre)
+      }
+      def goThis(tp: ThisType) = {
+        val d = go(tp.underlying)
+        if (d.exists) d
+        else
+          // There is a special case to handle:
+          //   trait Super { this: Sub => private class Inner {} println(this.Inner) }
+          //   class Sub extends Super
+          // When resolving Super.this.Inner, the normal logic goes to the self type and
+          // looks for Inner from there. But this fails because Inner is private.
+          // We fix the problem by having the following fallback case, which links up the
+          // member in Super instead of Sub.
+          // As an example of this in the wild, see
+          // loadClassWithPrivateInnerAndSubSelf in ShowClassTests
+          go(tp.cls.typeRef) orElse d
+      }
+      def goAnd(l: Type, r: Type) = go(l) & (go(r), pre)
+      def goOr(l: Type, r: Type) = go(l) | (go(r), pre)
+      go(this)
     } catch {
       case ex: MergeError =>
         throw new MergeError(s"${ex.getMessage} as members of type ${pre.show}")
@@ -843,26 +851,12 @@ object Types {
     /** A simplified version of this type which is equivalent wrt =:= to this type.
      *  This applies a typemap to the type which (as all typemaps) follows type
      *  variable instances and reduces typerefs over refined types. It also
-     *  re-evaluatesall occurrences of And/OrType with &/| because
+     *  re-evaluates all occurrences of And/OrType with &/| because
      *  what was a union or intersection of type variables might be a simpler type
      *  after the type variables are instantiated. Finally, it
      *  maps poly params in the current constraint set back to their type vars.
      */
-    def simplified(implicit ctx: Context) = {
-      class Simplify extends TypeMap {
-        def apply(tp: Type): Type = tp match {
-          case AndType(l, r) =>
-            this(l) & this(r)
-          case OrType(l, r) =>
-            this(l) | this(r)
-          case tp: PolyParam =>
-            ctx.typerState.constraint.typeVarOfParam(tp) orElse tp
-          case _ =>
-            mapOver(tp)
-        }
-      }
-      new Simplify().apply(this)
-    }
+    def simplified(implicit ctx: Context) = ctx.simplify(this, null)
 
     /** customized hash code of this type.
      *  NotCached for uncached types. Cached types
@@ -2096,7 +2090,8 @@ object Types {
         tp.derivedSelect(this(tp.prefix))
 
       case _: ThisType
-         | _: BoundType => tp
+         | _: BoundType
+         | NoPrefix => tp
 
       case tp: RefinedType =>
         tp.derivedRefinedType(this(tp.parent), tp.refinedName, this(tp.refinedInfo))
@@ -2217,7 +2212,8 @@ object Types {
         this(x, tp.prefix)
 
       case _: ThisType
-         | _: BoundType => x
+         | _: BoundType
+         | NoPrefix => x
 
       case tp: RefinedType =>
         this(this(x, tp.parent), tp.refinedInfo)
diff --git a/src/dotty/tools/dotc/core/pickling/ClassfileParser.scala b/src/dotty/tools/dotc/core/pickling/ClassfileParser.scala
index 0fc661842..1395b4f43 100644
--- a/src/dotty/tools/dotc/core/pickling/ClassfileParser.scala
+++ b/src/dotty/tools/dotc/core/pickling/ClassfileParser.scala
@@ -239,13 +239,13 @@ class ClassfileParser(
         case BOOL_TAG   => defn.BooleanType
         case 'L' =>
           def processInner(tp: Type): Type = tp match {
-            case tp @ TypeRef(pre, name) if !(tp.symbol.owner is Flags.ModuleClass) =>
-              TypeRef(processInner(pre.widen), name)
+            case tp: TypeRef if !(tp.symbol.owner is Flags.ModuleClass) =>
+              TypeRef(processInner(tp.prefix.widen), tp.name)
             case _ =>
               tp
           }
           def processClassType(tp: Type): Type = tp match {
-            case tp @ TypeRef(pre, name) =>
+            case tp: TypeRef =>
               if (sig(index) == '<') {
                 accept('<')
                 var tp1: Type = tp
diff --git a/src/dotty/tools/dotc/printing/PlainPrinter.scala b/src/dotty/tools/dotc/printing/PlainPrinter.scala
index 71c255c17..84936fbac 100644
--- a/src/dotty/tools/dotc/printing/PlainPrinter.scala
+++ b/src/dotty/tools/dotc/printing/PlainPrinter.scala
@@ -100,8 +100,8 @@ class PlainPrinter(_ctx: Context) extends Printer {
         toText(tp.underlying) ~ ".type"
       case tp: SingletonType =>
         toText(tp.underlying) ~ "(" ~ toTextRef(tp) ~ ")"
-      case tp @ TypeRef(pre, name) =>
-        toTextPrefix(pre) ~ selectionString(tp)
+      case tp: TypeRef =>
+        toTextPrefix(tp.prefix) ~ selectionString(tp)
       case tp: RefinedType =>
         // return tp.toString // !!! DEBUG
         val parent :: (refined: List[RefinedType]) =
@@ -187,8 +187,8 @@ class PlainPrinter(_ctx: Context) extends Printer {
   /** The string representation of this type used as a prefix */
   protected def toTextRef(tp: SingletonType): Text = controlled {
     tp match {
-      case tp @ TermRef(pre, name) =>
-        toTextPrefix(pre) ~ selectionString(tp)
+      case tp: TermRef =>
+        toTextPrefix(tp.prefix) ~ selectionString(tp)
       case ThisType(cls) =>
         nameString(cls) + ".this"
       case SuperType(thistpe: SingletonType, _) =>
diff --git a/src/dotty/tools/dotc/printing/RefinedPrinter.scala b/src/dotty/tools/dotc/printing/RefinedPrinter.scala
index df00280ac..87f9fc29e 100644
--- a/src/dotty/tools/dotc/printing/RefinedPrinter.scala
+++ b/src/dotty/tools/dotc/printing/RefinedPrinter.scala
@@ -57,7 +57,7 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
     tp match {
       case ThisType(cls) =>
         if (isOmittablePrefix(cls)) return ""
-      case tp @ TermRef(pre, name) =>
+      case tp @ TermRef(pre, _) =>
         val sym = tp.symbol
         if (sym.isPackageObject) return toTextPrefix(pre)
         if (isOmittablePrefix(sym)) return ""
@@ -109,7 +109,7 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
         }
       case tp: ViewProto =>
         return toText(tp.argType) ~ " ?=>? " ~ toText(tp.resultType)
-      case tp @ TypeRef(pre, name) =>
+      case tp: TypeRef =>
         if (tp.symbol is TypeParam | TypeArgument) {
           return tp.info match {
             case TypeAlias(hi) => toText(hi)
diff --git a/src/dotty/tools/dotc/typer/Applications.scala b/src/dotty/tools/dotc/typer/Applications.scala
index 63117e2ac..15dd0e9ad 100644
--- a/src/dotty/tools/dotc/typer/Applications.scala
+++ b/src/dotty/tools/dotc/typer/Applications.scala
@@ -223,7 +223,7 @@ trait Applications extends Compatibility { self: Typer =>
               if (meth.isClassConstructor) {
                 // default getters for class constructors are found in the companion object
                 mpre.baseType(cls) match {
-                  case TypeRef(clspre, _) => ref(clspre, cls.companionModule)
+                  case tp: TypeRef => ref(tp.prefix, cls.companionModule)
                   case _ => NoType
                 }
               } else mpre
diff --git a/src/dotty/tools/dotc/typer/Typer.scala b/src/dotty/tools/dotc/typer/Typer.scala
index 8c066cdd0..25721ad74 100644
--- a/src/dotty/tools/dotc/typer/Typer.scala
+++ b/src/dotty/tools/dotc/typer/Typer.scala
@@ -63,26 +63,23 @@ class Typer extends Namer with Applications with Implicits {
    */
   private var importedFromRoot: Set[Symbol] = Set()
 
- /** A denotation exists really if it exists and does not point to a stale symbol.
-  def reallyExists(denot: Denotation)(implicit ctx: Context): Boolean = denot match {
-    case denot: SymDenotation =>
-      denot.ensureCompleted
-      denot.exists && !denot.isAbsent
-    case _ =>
-      true
-  }*/
-
-  /** A denotation exists really if it exists and does not point to a stale symbol. */
-  def reallyExists(denot: Denotation)(implicit ctx: Context): Boolean =
-    try
-      denot.exists && {
+ /** A denotation exists really if it exists and does not point to a stale symbol. */
+  final def reallyExists(denot: Denotation)(implicit ctx: Context): Boolean = try
+    denot match {
+      case denot: SymDenotation =>
+        denot.exists && {
+          denot.ensureCompleted
+          !denot.isAbsent
+        }
+      case denot: SingleDenotation =>
         val sym = denot.symbol
-            sym.ensureCompleted
-            (sym eq NoSymbol) || !sym.isAbsent
-      }
-    catch {
-      case ex: StaleSymbol => false
+        (sym eq NoSymbol) || reallyExists(sym.denot)
+      case _ =>
+        true
     }
+  catch {
+    case ex: StaleSymbol => false
+  }
 
   /** The type of a selection with `name` of a tree with type `site`.
    */