Sped up hashCode by removing megamorphic call to _identityHashCode.

runtime/vm/code_generator.cc

 // Copyright (c) 2013, 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.
 
 #include "vm/code_generator.h"
 
 #include "vm/assembler.h"
 #include "vm/ast.h"
 #include "vm/code_patcher.h"
 #include "vm/compiler.h"
@@ skipping 764 matching lines @@
           target_function.IsNull() ? "null" : target_function.ToCString());
     }
     result = target_function.raw();
   }
   // May be null if --no-lazy-dispatchers, in which case dispatch will be
   // handled by InvokeNoSuchMethodDispatcher.
   ASSERT(!result.IsNull() || !FLAG_lazy_dispatchers);
   return result.raw();
 }
 
+
+// Perform the subtype and return constant function based on the result.
+static RawFunction* ComputeTypeCheckTarget(const Instance& receiver,
+                                           const AbstractType& type,
+                                           const ArgumentsDescriptor& desc) {
+  const TypeArguments& checked_type_arguments = TypeArguments::Handle();
+  Error& error = Error::Handle();
+  bool result = receiver.IsInstanceOf(type, checked_type_arguments, &error);
+  ASSERT(error.IsNull());
+  ObjectStore* store = Isolate::Current()->object_store();
+  Function& target
+      = Function::Handle(result
+                         ? store->simple_instance_of_true_function()
+                         : store->simple_instance_of_false_function());
+  ASSERT(!target.IsNull());
+  return target.raw();;
+}
+
+
 static RawFunction* InlineCacheMissHandler(
     const GrowableArray<const Instance*>& args,
     const ICData& ic_data) {
   const Instance& receiver = *args[0];
   ArgumentsDescriptor
       arguments_descriptor(Array::Handle(ic_data.arguments_descriptor()));
   String& function_name = String::Handle(ic_data.target_name());
   ASSERT(function_name.IsSymbol());
+
   Function& target_function = Function::Handle(
       Resolver::ResolveDynamic(receiver, function_name, arguments_descriptor));
+
+  ObjectStore* store = Isolate::Current()->object_store();
+  if (target_function.raw() == store->simple_instance_of_function()) {
+    // Replace the target function with constant function.
+    const AbstractType& type = AbstractType::Cast(*args[1]);
+    target_function
+        = ComputeTypeCheckTarget(receiver, type, arguments_descriptor);
+  }
   if (target_function.IsNull()) {
     if (FLAG_trace_ic) {
       OS::PrintErr("InlineCacheMissHandler NULL function for %s receiver: %s\n",
                    String::Handle(ic_data.target_name()).ToCString(),
                    receiver.ToCString());
     }
     const Array& args_descriptor =
         Array::Handle(ic_data.arguments_descriptor());
     const String& target_name = String::Handle(ic_data.target_name());
     target_function = InlineCacheMissHelper(receiver,
@@ skipping 1097 matching lines @@
   const intptr_t elm_size = old_data.ElementSizeInBytes();
   const TypedData& new_data =
       TypedData::Handle(TypedData::New(cid, new_size, Heap::kOld));
   TypedData::Copy(new_data, 0, old_data, 0, old_size * elm_size);
   typed_data_cell.SetAt(0, new_data);
   arguments.SetReturn(new_data);
 }
 
 
 }  // namespace dart