Reorder pattern match based on frequency

foldOver total number of matches when compiling
the dotty bootstrapped compiler

(TypeRef,880390)
(AppliedType,276595)
(BoundType,122879)
(ThisType,117388)
(LambdaType,95690)
(NoPrefix,94493)
(TermRef,88508)
(TypeVar,30322)
(ExprType,16702)
(TypeBounds,16432)
(AndOrType,6234)
(AnnotatedType,5948)
(default,5252)
(ProtoType,4044)
(RefinedType,3270)
(WildcardType,2064)
(ClassInfo,1520)
(JavaArrayType,516)
(SkolemType,210)
(TypeArgRef,98)
(SuperType,77)
(LazyRef,3)

Author: nicolasstucki

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

@@ -4198,14 +4198,6 @@ object Types {
           val tp1 = tp.prefix.lookupRefined(tp.name)
           if (tp1.exists) this(x, tp1) else applyToPrefix(x, tp)
         }
-      case tp: TermRef =>
-        if (stopAtStatic && tp.currentSymbol.isStatic) x
-        else applyToPrefix(x, tp)
-
-      case _: ThisType
-         | _: BoundType
-         | NoPrefix => x
-
       case tp @ AppliedType(tycon, args) =>
         @tailrec def foldArgs(x: T, tparams: List[ParamInfo], args: List[Type]): T =
           if (args.isEmpty) {
@@ -4221,10 +4213,20 @@ object Types {
             foldArgs(acc, tparams.tail, args.tail)
           }
         foldArgs(this(x, tycon), tp.typeParams, args)
-
-      case tp: RefinedType =>
-        this(this(x, tp.parent), tp.refinedInfo)
-
+      case _: BoundType | _: ThisType => x
+      case tp: LambdaType =>
+        variance = -variance
+        val y = foldOver(x, tp.paramInfos)
+        variance = -variance
+        this(y, tp.resultType)
+      case NoPrefix => x
+      case tp: TermRef =>
+        if (stopAtStatic && tp.currentSymbol.isStatic) x
+        else applyToPrefix(x, tp)
+      case tp: TypeVar =>
+        this(x, tp.underlying)
+      case ExprType(restpe) =>
+        this(x, restpe)
       case bounds @ TypeBounds(lo, hi) =>
         if (lo eq hi) atVariance(0)(this(x, lo))
         else {
@@ -4233,52 +4235,30 @@ object Types {
           variance = -variance
           this(y, hi)
         }
-
-      case tp: RecType =>
-        this(x, tp.parent)
-
-      case ExprType(restpe) =>
-        this(x, restpe)
-
-      case tp: TypeVar =>
-        this(x, tp.underlying)
-
-      case SuperType(thistp, supertp) =>
-        this(this(x, thistp), supertp)
-
-      case tp @ ClassInfo(prefix, _, _, _, _) =>
-        this(x, prefix)
-
-      case tp: LambdaType =>
-        variance = -variance
-        val y = foldOver(x, tp.paramInfos)
-        variance = -variance
-        this(y, tp.resultType)
-
       case tp: AndOrType =>
         this(this(x, tp.tp1), tp.tp2)
-
-      case tp: SkolemType =>
-        this(x, tp.info)
-
-      case tp @ TypeArgRef(prefix, _, _) =>
-        atVariance(0)(this(x, prefix))
-
       case AnnotatedType(underlying, annot) =>
         this(applyToAnnot(x, annot), underlying)
-
+      case tp: ProtoType =>
+        tp.fold(x, this)
+      case tp: RefinedType =>
+        this(this(x, tp.parent), tp.refinedInfo)
       case tp: WildcardType =>
         this(x, tp.optBounds)
-
+      case tp @ ClassInfo(prefix, _, _, _, _) =>
+        this(x, prefix)
       case tp: JavaArrayType =>
         this(x, tp.elemType)
-
+      case tp: SkolemType =>
+        this(x, tp.info)
+      case tp @ TypeArgRef(prefix, _, _) =>
+        atVariance(0)(this(x, prefix))
+      case SuperType(thistp, supertp) =>
+        this(this(x, thistp), supertp)
       case tp: LazyRef =>
         this(x, tp.ref)
-
-      case tp: ProtoType =>
-        tp.fold(x, this)
-
+      case tp: RecType =>
+        this(x, tp.parent)
       case _ => x
     }}
 
@@ -4446,3 +4426,15 @@ object Types {
 
   implicit def decorateTypeApplications(tpe: Type): TypeApplications = new TypeApplications(tpe)
 }
+
+object stats {
+  val map = scala.collection.mutable.LinkedHashMap.empty[String, Int]
+
+  def register(name: String): Unit = map.update(name, map.getOrElse(name, 0) + 1)
+
+  override def toString: String = {
+    ("=" * 20) + "\n" +
+      map.toArray.sortBy(_._2).reverse.mkString("\n") +
+      "\n" + ("-" * 20)
+  }
+}