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

lib/compiler/implementation/universe.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 class Universe {
   Map<Element, CodeBuffer> generatedCode;
   Map<Element, CodeBuffer> generatedBailoutCode;
   final Set<ClassElement> instantiatedClasses;
   final Set<SourceString> instantiatedClassInstanceFields;
   final Set<FunctionElement> staticFunctionsNeedingGetter;
   final Map<SourceString, Set<Selector>> invokedNames;
   final Map<SourceString, Set<Selector>> invokedGetters;
   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>(),
                generatedBailoutCode = new Map<Element, CodeBuffer>(),
                instantiatedClasses = new Set<ClassElement>(),
                instantiatedClassInstanceFields = new Set<SourceString>(),
                staticFunctionsNeedingGetter = new Set<FunctionElement>(),
                invokedNames = new Map<SourceString, Set<Selector>>(),
                invokedGetters = new Map<SourceString, Set<Selector>>(),
                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;
   }
 
   void addBailoutCode(WorkItem work, CodeBuffer codeBuffer) {
     generatedBailoutCode[work.element] = codeBuffer;
   }
 
   bool hasMatchingSelector(Set<Selector> selectors,
                            Element member,
@@ skipping 343 matching lines @@
     }
 
     return false;
   }
 
   toString() {
     return 'Selector($kind, "${name.slowToString()}", '
            '$argumentCount, type=$receiverType)';
   }
 }