Merge branch 'mark-box-unbox' into add-reified-values

Author: AragornXu

compiler/src/dotty/tools/backend/jvm/BCodeBodyBuilder.scala

@@ -826,8 +826,7 @@ trait BCodeBodyBuilder extends BCodeSkelBuilder {
           genLoad(expr, nativeKind)
           val MethodNameAndType(mname, methodType) = asmBoxTo(nativeKind)
           val hasExtraBoxAttach = app.getAttachment(NoBoxingNeeded).isDefined
-          if hasExtraBoxAttach then
-            println(s"Debug: extra box attach found on ${app.show}")
+          // if hasExtraBoxAttach then println(s"Debug: extra box attach found on ${app.show}")
           bc.invokestatic(srBoxesRuntimeRef.internalName, mname, methodType.descriptor, itf = false, extraBoxingUnboxing = hasExtraBoxAttach)
           generatedType = boxResultType(fun.symbol) // was toTypeKind(fun.symbol.tpe.resultType)
 
@@ -837,8 +836,7 @@ trait BCodeBodyBuilder extends BCodeSkelBuilder {
           generatedType = boxType
           val MethodNameAndType(mname, methodType) = asmUnboxTo(boxType)
           val hasExtraUnboxAttach = app.getAttachment(NoUnboxingNeeded).isDefined
-          if hasExtraUnboxAttach then
-            println(s"Debug: extra unbox attach found on ${app.show}")
+          // if hasExtraUnboxAttach then println(s"Debug: extra unbox attach found on ${app.show}")
           bc.invokestatic(srBoxesRuntimeRef.internalName, mname, methodType.descriptor, itf = false, extraBoxingUnboxing = hasExtraUnboxAttach)
 
         case app @ Apply(fun, args) =>

compiler/src/dotty/tools/backend/jvm/BCodeHelpers.scala

@@ -775,10 +775,8 @@ trait BCodeHelpers extends BCodeIdiomatic {
       * signatures, e.g. `def apply(i: Int): T`. A TyperRef to T is replaced by ObjectReference.
       */
     def nonClassTypeRefToBType(sym: Symbol): ClassBType = {
-      if (sym == defn.ObjectAnySymbol) ObjectRef
-      else
-        assert(sym.isType && compilingArray, sym)
-        ObjectRef.asInstanceOf[ct.bTypes.ClassBType]
+      assert(sym.isType && compilingArray, sym)
+      ObjectRef.asInstanceOf[ct.bTypes.ClassBType]
     }
 
     tp.widenDealias match {

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

@@ -113,7 +113,8 @@ class Compiler {
     List(new AddReifiedTypes) ::     // Add reified type parameters
     List(new ErasurePreservation) :: //
     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 implementation types
+    List(new ElimObjectAny,          // Eliminate ObjcetAny to Object
+         new ElimErasedValueType,    // Expand erased value types to their underlying implementation types
          new PureStats,              // Remove pure stats from blocks
          new VCElideAllocations,     // Peep-hole optimization to eliminate unnecessary value class allocations
          new EtaReduce,              // Reduce eta expansions of pure paths to the underlying function reference

compiler/src/dotty/tools/dotc/transform/ElimObjectAny.scala

@@ -0,0 +1,51 @@
+package dotty.tools
+package dotc
+package transform
+
+import ast.Trees
+import core.Phases.*
+import core.Contexts.*
+import core.Types.*
+import dotty.tools.dotc.transform.MegaPhase.MiniPhase
+import dotty.tools.dotc.core.Symbols.defn
+import dotty.tools.dotc.core.DenotTransformers.DenotTransformer
+import dotty.tools.dotc.core.Denotations.SingleDenotation
+import dotty.tools.dotc.core.DenotTransformers.InfoTransformer
+import dotty.tools.dotc.core.Symbols.*
+
+class ElimObjectAny extends MiniPhase with InfoTransformer{
+  import ast.tpd._
+  
+  override def phaseName: String = ElimObjectAny.name
+
+  override def description: String = ElimObjectAny.description
+
+  def elimObjectAny(tp: Type)(using Context): Type = 
+    new TypeMap {
+      def apply(tp: Type): Type = 
+        if tp eq defn.ObjectAnyType then
+          // println(s"ElimObjectAny: visiting type $tp")
+          defn.ObjectType
+        else
+          mapOver(tp)
+    }.apply(tp)
+
+  override def transformInfo(tp: Type, sym: Symbol)(using Context): Type =
+    elimObjectAny(tp)
+
+  override def transformTypeTree(tree: TypeTree)(using Context): Tree =
+    val newType = elimObjectAny(tree.tpe)
+    if (newType ne tree.tpe) then tree.withType(newType)
+    else tree
+  // def changeObjectAnyToObject(tp: Type)(using Context): Type = {
+  //   tp match 
+  //       case tr: TypeRef if tr.symbol == defn.ObjectAnySymbol =>
+  //         defn.ObjectType
+  //       case _ => tp
+  // }
+}
+
+object ElimObjectAny {
+  val name: String = "elimObjectAny"
+  val description: String = "Eliminate ObjectAny to Object"
+}

compiler/src/dotty/tools/dotc/transform/Erasure.scala

@@ -251,13 +251,13 @@ object Erasure {
 
     def maybeMarkBox(tree: Tree, tp: Type)(using Context): Tree =
       if (isObjectAny(tp)) then
-        println("  MarkBoxing: marking box for "+ tp)
+        // println("  MarkBoxing: marking box for "+ tp)
         tree.withAttachment(NoBoxingNeeded, tp.typeSymbol.name.toString)
       else tree
 
     def maybeMarkUnbox(tree: Tree, tp: Type)(using Context): Tree =
       if (isObjectAny(tp)) then
-        println("  MarkBoxing: marking unbox for "+ tp)
+        // println("  MarkBoxing: marking unbox for "+ tp)
         tree.withAttachment(NoUnboxingNeeded, tp.typeSymbol.name.toString)
       else tree
 
@@ -390,9 +390,9 @@ object Erasure {
         case _ =>
           if (pt.isPrimitiveValueType)
             primitiveConversion(tree, pt.classSymbol)
-          // cast tree type to pt, if pt is ObjectAny, do not inject a cast
+          // cast tree type to pt, if pt is ObjectAny and tpe of tree is not primitive, do not inject a cast
           else if isObjectAny(pt) && !tree.tpe.widen.isPrimitiveValueType then
-            println("  MarkBoxing: skipping cast to ObjectAny for "+ pt + " from tree "+ tree.show)
+            // println("  MarkBoxing: skipping cast to ObjectAny for "+ pt + " from tree "+ tree.show)
             tree.withType(pt)
           else
             tree.asInstance(pt)