Collect the types used in is-checks in the resolver phase.

lib/compiler/implementation/universe.dart

Index: lib/compiler/implementation/universe.dart
diff --git a/lib/compiler/implementation/universe.dart b/lib/compiler/implementation/universe.dart
index a03a61c7295d92f44e19ced9a4a85f67449360d7..2e0f6b1412d68317c9c3b99a6bc37d64e2aa1a4a 100644
--- a/lib/compiler/implementation/universe.dart
+++ b/lib/compiler/implementation/universe.dart
@@ -13,8 +13,9 @@ class Universe {
   final Map<SourceString, Set<Selector>> invokedSetters;
   final Map<SourceString, Set<Selector>> fieldGetters;
   final Map<SourceString, Set<Selector>> fieldSetters;
-  // TODO(ngeoffray): This should be a Set<DartType>.
-  final Set<Element> isChecks;
+  final Set<DartType> isChecks;
+  // TODO(karlklose): move this data to RuntimeTypeInformation.
+  Set<Element> checkedClasses;
   final RuntimeTypeInformation rti;
 
   Universe() : generatedCode = new Map<Element, CodeBuffer>(),
@@ -27,9 +28,16 @@ class Universe {
                invokedSetters = new Map<SourceString, Set<Selector>>(),
                fieldGetters = new Map<SourceString, Set<Selector>>(),
                fieldSetters = new Map<SourceString, Set<Selector>>(),
-               isChecks = new Set<Element>(),
+               isChecks = new Set<DartType>(),
                rti = new RuntimeTypeInformation();
 
+  // TODO(karlklose): add the set of instantiatedtypes as second argument.

[ngeoffray, 2012/09/05 12:50:40]

Why is the set of instantiatedTypes needed? You want to remove classes that are
not in that set? Do you really care? The backend runs through the list of
instantiated classes anyway.

[karlklose, 2012/09/06 11:04:02]

It is important for checks on type arguments to know what type instantiations
can occur.

[ngeoffray, 2012/09/06 11:07:46]

So you can just return false for them?

+  void computeRequiredTypes(Set<DartType> isChecks) {
+    assert(checkedClasses == null);
+    checkedClasses = new Set<Element>();
+    isChecks.forEach((DartType t) => checkedClasses.add(t.element));
+  }
+
   void addGeneratedCode(WorkItem work, CodeBuffer codeBuffer) {
     generatedCode[work.element] = codeBuffer;
   }