Optimize some operations on TupleXXL

Author: nicolasstucki

compiler/src/dotty/tools/dotc/Compiler.scala

@@ -87,7 +87,7 @@ class Compiler {
          new AugmentScala2Traits,    // Augments Scala2 traits with additional members needed for mixin composition.
          new ResolveSuper,           // Implement super accessors
          new FunctionXXLForwarders,  // Add forwarders for FunctionXXL apply method
-         new TuplesOptimizations,    // Optimize generic operations on tuples
+         new TupleOptimizations,     // Optimize generic operations on tuples
          new ArrayConstructors) ::   // Intercept creation of (non-generic) arrays and intrinsify.
     List(new Erasure) ::             // Rewrite types to JVM model, erasing all type parameters, abstract types and refinements.
     List(new ElimErasedValueType,    // Expand erased value types to their underlying implmementation types

compiler/src/dotty/tools/dotc/transform/TuplesOptimizations.scala renamed to compiler/src/dotty/tools/dotc/transform/TupleOptimizations.scala

@@ -18,7 +18,7 @@ import dotty.tools.dotc.ast.tpd
 import scala.annotation.tailrec
 
 /** Optimize generic operations on tuples */
-class TuplesOptimizations extends MiniPhase with IdentityDenotTransformer {
+class TupleOptimizations extends MiniPhase with IdentityDenotTransformer {
   import tpd._
 
   def phaseName: String = "genericTuples"
@@ -80,7 +80,7 @@ class TuplesOptimizations extends MiniPhase with IdentityDenotTransformer {
             val elements = (1 until size).map(i => tup.select(nme.selectorName(i))).toList
             knownTupleFromElements(tpes.tail, elements)
           }
-        } else {
+        } else if (size <= MaxTupleArity + 1) {
           // val it = this.asInstanceOf[Product].productIterator
           // it.next()
           // TupleN-1(it.next(), ..., it.next())
@@ -90,6 +90,9 @@ class TuplesOptimizations extends MiniPhase with IdentityDenotTransformer {
               knownTupleFromIterator(size - 1, it).asInstance(tree.tpe)
             )
           }
+        } else {
+          // tup.asInstanceOf[TupleXXL].tailXXL
+          tup.asInstance(defn.TupleXXLType).select("tailXXL".toTermName)
         }
       case None =>
         // No optimization, keep:
@@ -183,8 +186,8 @@ class TuplesOptimizations extends MiniPhase with IdentityDenotTransformer {
           // DynamicTuple.productToArray(tup.asInstanceOf[Product])
           ref(defn.DynamicTuple_productToArray).appliedTo(tup.asInstance(defn.ProductType))
         } else {
-          // tup.asInstanceOf[TupleXXL].elems
-          tup.asInstance(defn.TupleXXLType).select(nme.elems)
+          // tup.asInstanceOf[TupleXXL].elems.clone()
+          tup.asInstance(defn.TupleXXLType).select(nme.toArray)
         }
       case None =>
         // No optimization, keep:

library/src-3.x/scala/runtime/DynamicTuple.scala

@@ -175,12 +175,9 @@ object DynamicTuple {
 
 
   def dynamicToArray(self: Tuple): Array[Object] = (self: Any) match {
-    case self: Unit =>
-      Array.emptyObjectArray
-    case self: TupleXXL =>
-      self.elems
-    case self: Product =>
-      productToArray(self)
+    case self: Unit => Array.emptyObjectArray
+    case self: TupleXXL => self.toArray
+    case self: Product => productToArray(self)
   }
 
   def productToArray(self: Product): Array[Object] = {
@@ -222,7 +219,6 @@ object DynamicTuple {
 
   def dynamicSize[This <: Tuple](self: This): Size[This] = (self: Any) match {
     case self: Unit => 0.asInstanceOf[Size[This]]
-    case self: TupleXXL => self.elems.length.asInstanceOf[Size[This]]
     case self: Product => self.productArity.asInstanceOf[Size[This]]
   }
 

library/src/scala/TupleXXL.scala

@@ -19,6 +19,13 @@ final class TupleXXL private (es: Array[Object]) extends Product {
     case _ => false
   }
   def elems: Array[Object] = es
+
+  def tailXXL: TupleXXL = {
+    assert(es.length > 23)
+    new TupleXXL(es.tail)
+  }
+
+  def toArray: Array[Object] = es.clone
 }
 object TupleXXL {
   def fromIterator(elems: Iterator[Any]) = new TupleXXL(elems.map(_.asInstanceOf[Object]).toArray)