Add runtimeType() to Object which returns canonicalized instances of Type.

lib/compiler/implementation/ssa/builder.dart

Index: lib/compiler/implementation/ssa/builder.dart
diff --git a/lib/compiler/implementation/ssa/builder.dart b/lib/compiler/implementation/ssa/builder.dart
index 75c7877de8d50ca3b1f5d008465d0361af8e9761..8fcda31c6bef30d3c0fd03a334ecf85b067a2370 100644
--- a/lib/compiler/implementation/ssa/builder.dart
+++ b/lib/compiler/implementation/ssa/builder.dart
@@ -1242,14 +1242,13 @@ class SsaBuilder extends ResolvedVisitor implements Visitor {
     HForeignNew newObject = new HForeignNew(classElement, constructorArguments);
     add(newObject);
 
-    // If the class has type variables, create the runtime type
-    // information with the type parameters provided.
-    if (!classElement.typeVariables.isEmpty()) {
-      List<HInstruction> rtiInputs = <HInstruction>[];
+    // Create the runtime type information, if needed.
+    if (needsRuntimeTypeInfo(classElement)) {
+      List<HInstruction> inputs = <HInstruction>[];
       classElement.typeVariables.forEach((TypeVariableType typeVariable) {
-        rtiInputs.add(localsHandler.directLocals[typeVariable.element]);
+        inputs.add(localsHandler.directLocals[typeVariable.element]);
       });
-      callSetRuntimeTypeInfo(classElement, rtiInputs, newObject);
+      callSetRuntimeTypeInfo(classElement, inputs, newObject);
     }
 
     // Generate calls to the constructor bodies.
@@ -2638,7 +2637,7 @@ class SsaBuilder extends ResolvedVisitor implements Visitor {
   void handleListConstructor(InterfaceType type,
                              Node currentNode,
                              HInstruction newObject) {
-    if (type.arguments.isEmpty()) return;
+    if (!needsRuntimeTypeInfo(type.element)) return;
     List<HInstruction> inputs = <HInstruction>[];
     type.arguments.forEach((DartType argument) {
       inputs.add(analyzeTypeArgument(argument, currentNode));
@@ -2646,23 +2645,64 @@ class SsaBuilder extends ResolvedVisitor implements Visitor {
     callSetRuntimeTypeInfo(type.element, inputs, newObject);
   }
 
+  // Runtime type information is required if the type has type
+  // variables or if the program calls [runtimeType].
+  // TODO(karlklose): it is unnecessary for type variables that
+  // can never match an is-Check.
+  bool needsRuntimeTypeInfo(ClassElement element) {
+    bool classHasTypeVariables = !element.typeVariables.isEmpty();
+    bool runtimeTypeIsUsed = compiler.enabledRuntimeType;
+    return (classHasTypeVariables || runtimeTypeIsUsed);
+  }
+
   void callSetRuntimeTypeInfo(ClassElement element,
-                              List<HInstruction> inputs,
+                              List<HInstruction> rtiInputs,
                               HInstruction newObject) {
-    List<String> typeVariables = <String>[];
-    element.typeVariables.forEach((TypeVariableType typeVariable) {
-      typeVariables.add("'$typeVariable': #");
-    });
-
-    String jsCode = '{ ${Strings.join(typeVariables, ', ')} }';
-    HInstruction typeInfo = new HForeign(new LiteralDartString(jsCode),
-                                         new LiteralDartString('Object'),
-                                         inputs);
-    add(typeInfo);
+    bool classHasTypeVariables = !element.typeVariables.isEmpty();
+    bool runtimeTypeIsUsed = compiler.enabledRuntimeType;
+
+    // Construct the runtime type information.
+    HInstruction runtimeType;
+    HInstruction typeInfo;

[kasperl, 2012/09/14 12:35:37]

Isn't this typeInfo variable unused (shadowed)?

[karlklose, 2012/09/17 14:50:37]

Done, removed.

+    StringBuffer runtimeCode = new StringBuffer();
+    List<HInstruction> runtimeCodeInputs = <HInstruction>[];
+    if (runtimeTypeIsUsed) {
+      String runtimeTypeString =
+          RuntimeTypeInformation.generateRuntimeTypeString(element,
+                                                           rtiInputs.length);
+      runtimeType =

[kasperl, 2012/09/14 12:35:37]

Can't you declare runtimeType here?

[karlklose, 2012/09/17 14:50:37]

Done.

+          new HForeign(new LiteralDartString(runtimeTypeString),
+                       new LiteralDartString('String'),
+                       rtiInputs);
+      add(runtimeType);
+      runtimeCodeInputs.add(runtimeType);
+      runtimeCode.add('runtimeType: #');
+    }
+    if (classHasTypeVariables) {
+      if (runtimeTypeIsUsed) runtimeCode.add(', ');
+      String typeVariablesString =
+          RuntimeTypeInformation.generateTypeVariableString(element,
+                                                            rtiInputs.length);
+      HInstruction typeInfo =

[kasperl, 2012/09/14 12:35:37]

Add a helper for this creation of a new foreign string thing? Seems like it
could be used in three cases (if you parameterize it with code, type, and
inputs). Maybe it would actually be useful in other places too?

[karlklose, 2012/09/17 14:50:37]

Done.

+          new HForeign(new LiteralDartString(typeVariablesString),
+                       new LiteralDartString('String'),
+                       rtiInputs);
+      add(typeInfo);
+      runtimeCodeInputs.add(typeInfo);
+      runtimeCode.add('#');
+    }
+    HInstruction runtimeInfo =
+        new HForeign(new LiteralDartString("{$runtimeCode}"),
+                     new LiteralDartString('Object'),
+                     runtimeCodeInputs);
+    add(runtimeInfo);
+
+    // Set the runtime type information on the object.
     Element typeInfoSetterElement = interceptors.getSetRuntimeTypeInfo();
     HInstruction typeInfoSetter = new HStatic(typeInfoSetterElement);
     add(typeInfoSetter);
-    add(new HInvokeStatic(<HInstruction>[typeInfoSetter, newObject, typeInfo]));
+    add(new HInvokeStatic(
+        <HInstruction>[typeInfoSetter, newObject, runtimeInfo]));
   }
 
   visitNewSend(Send node) {