- added weakIsInstance method in ScalaClassType...

- added weakIsInstance method in ScalaClassType, which make it possible
to slightly optimise instance tests when the type is that of a known
class (e.g. x.isInstanceOf[C[T]])

5 files changed, 64 insertions, 3 deletions

diff --git a/sources/scala/runtime/types/ScalaClassType.java b/sources/scala/runtime/types/ScalaClassType.java
index b999f1bcfb..51f002e211 100644
--- a/sources/scala/runtime/types/ScalaClassType.java
+++ b/sources/scala/runtime/types/ScalaClassType.java
@@ -57,6 +57,11 @@ public class ScalaClassType extends ClassType {
                 || ((ScalaObject)o).getType().weakIsSubScalaClassType(this));
     }
 
+    public boolean weakIsInstance(Object o) {
+        assert Statistics.incWeakInstanceOf();
+        return ((ScalaObject)o).getType().weakIsSubScalaClassType(this);
+    }
+
     protected boolean isSubClassType(ClassType that) {
         return (this == that)
             || (super.isSubClassType(that)
diff --git a/sources/scala/runtime/types/Statistics.java b/sources/scala/runtime/types/Statistics.java
index 67091cb6e8..437c1bcb80 100644
--- a/sources/scala/runtime/types/Statistics.java
+++ b/sources/scala/runtime/types/Statistics.java
@@ -32,6 +32,7 @@ public class Statistics {
     private static long uniqueInstantiationsCount = 0;
 
     private static long instanceOfCount = 0;
+    private static long weakInstanceOfCount = 0;
     private static long typeCastCount = 0;
 
     private static long ancestorSearchIterations = 0;
@@ -69,6 +70,11 @@ public class Statistics {
         return true;
     }
 
+    public static synchronized boolean incWeakInstanceOf() {
+        ++weakInstanceOfCount;
+        return true;
+    }
+
     public static synchronized boolean decInstanceOf() {
         --instanceOfCount;
         return true;
@@ -112,6 +118,8 @@ public class Statistics {
                        + uniqueInstantiationsCount + ")");
         stream.println("(instance-of . "
                        + instanceOfCount + ")");
+        stream.println("(weak-instance-of . "
+                       + weakInstanceOfCount + ")");
         stream.println("(type-cast . "
                        + typeCastCount + ")");
         if (ancestorSearches > 0) {
diff --git a/sources/scalac/symtab/Definitions.java b/sources/scalac/symtab/Definitions.java
index 6dda72353e..8f306ab4ac 100644
--- a/sources/scalac/symtab/Definitions.java
+++ b/sources/scalac/symtab/Definitions.java
@@ -679,6 +679,14 @@ public class Definitions {
         return TYPECONSTRUCTOR_FUNCTIONOUTER;
     }
 
+    private Symbol SCALACLASSTYPE_WEAKISINSTANCE;
+    public Symbol SCALACLASSTYPE_WEAKISINSTANCE() {
+        if (SCALACLASSTYPE_WEAKISINSTANCE == null)
+            SCALACLASSTYPE_WEAKISINSTANCE =
+                loadTerm(SCALACLASSTYPE_CLASS, Names.weakIsInstance);
+        return SCALACLASSTYPE_WEAKISINSTANCE;
+    }
+
     private Symbol SCALACLASSTYPE_SETPARENTS;
     public Symbol SCALACLASSTYPE_SETPARENTS() {
         if (SCALACLASSTYPE_SETPARENTS == null)
diff --git a/sources/scalac/transformer/TypesAsValuesPhase.java b/sources/scalac/transformer/TypesAsValuesPhase.java
index b5dc28a0c0..e3ec60af48 100644
--- a/sources/scalac/transformer/TypesAsValuesPhase.java
+++ b/sources/scalac/transformer/TypesAsValuesPhase.java
@@ -329,7 +329,7 @@ public class TypesAsValuesPhase extends Phase {
         transformer.apply(unit);
     }
 
-    private class TV_Transformer extends GenTransformer {
+    private class TV_Transformer extends TV_MiniTransformer {
         private Symbol currentOwner;
 
         public TV_Transformer(Global global) {
@@ -736,8 +736,29 @@ public class TypesAsValuesPhase extends Phase {
          */
         private Tree genInstanceTest(int pos, Tree expr, Type tp) {
             Tree tpVal = typeAsValue(pos, tp, currentOwner, EENV);
-            Tree fun = gen.Select(pos, tpVal, defs.TYPE_ISINSTANCE());
-            return gen.mkApply_V(pos, fun, new Tree[] { expr });
+
+            if (isKnowClassType(tp) && isLocalIdent(expr)) {
+                Symbol sym = expr.symbol();
+                Tree cheapTest =
+                    gen.mkIsInstanceOf(pos, gen.mkLocalRef(pos, sym), tp, true);
+                Symbol weakIsInst = defs.SCALACLASSTYPE_WEAKISINSTANCE();
+                Tree scalaTpVal = gen.mkAsInstanceOf(pos,
+                                                     tpVal,
+                                                     defs.SCALACLASSTYPE_TYPE(),
+                                                     true);
+                Tree expensiveTest =
+                    gen.mkApply_V(pos,
+                                  gen.Select(pos, scalaTpVal, weakIsInst),
+                                  new Tree[] { expr });
+                return gen.mkApply_V(pos,
+                                     gen.Select(pos,
+                                                cheapTest,
+                                                defs.BOOLEAN_AND()),
+                                     new Tree[] { expensiveTest });
+            } else {
+                Tree fun = gen.Select(pos, tpVal, defs.TYPE_ISINSTANCE());
+                return gen.mkApply_V(pos, fun, new Tree[] { expr });
+            }
         }
 
         /**
@@ -783,6 +804,24 @@ public class TypesAsValuesPhase extends Phase {
                 return false;
         }
 
+        private boolean isKnowClassType(Type tp) {
+            switch (tp) {
+            case TypeRef(_, Symbol sym, _):
+                return (sym != defs.ARRAY_CLASS) && !sym.isParameter();
+            default:
+                return false;
+            }
+        }
+
+        private boolean isLocalIdent(Tree tree) {
+            switch (tree) {
+            case Ident(_):
+                return tree.symbol().isLocal();
+            default:
+                return false;
+            }
+        }
+
         /**
          * Transform a type into a tree representing it.
          */
diff --git a/sources/scalac/util/Names.java b/sources/scalac/util/Names.java
index 18013be172..0fda2848fe 100644
--- a/sources/scalac/util/Names.java
+++ b/sources/scalac/util/Names.java
@@ -222,6 +222,7 @@ public class Names {
     public static final Name update = Name.fromString("update");
     public static final Name view = Name.fromString("view");
     public static final Name wait = Name.fromString("wait");
+    public static final Name weakIsInstance = Name.fromString("weakIsInstance");
     public static final Name xml = Name.fromString("xml");