Fix bug in specialization of IC-data.

runtime/vm/flow_graph_optimizer.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/flow_graph_optimizer.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cha.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_builder.h"
@@ skipping 160 matching lines @@
     ic_data.AddCheck(class_ids, function);
   } else {
     ASSERT(class_ids.length() == 1);
     ic_data.AddReceiverCheck(class_ids[0], function);
   }
   call->set_ic_data(&ic_data);
   return true;
 }
 
 
-static const ICData& SpecializeICData(const ICData& ic_data, intptr_t cid) {
+static const ICData& TrySpecializeICData(const ICData& ic_data, intptr_t cid) {
   ASSERT(ic_data.num_args_tested() == 1);
 
   if ((ic_data.NumberOfChecks() == 1) &&
       (ic_data.GetReceiverClassIdAt(0) == cid)) {
     return ic_data;  // Nothing to do
   }
 
-  const ICData& new_ic_data = ICData::ZoneHandle(ICData::New(
-      Function::Handle(ic_data.function()),
-      String::Handle(ic_data.target_name()),
-      Object::empty_array(),  // Dummy argument descriptor.
-      ic_data.deopt_id(),
-      ic_data.num_args_tested()));
-  new_ic_data.set_deopt_reason(ic_data.deopt_reason());
-
   const Function& function =
       Function::Handle(ic_data.GetTargetForReceiverClassId(cid));
+  // TODO(fschneider): Try looking up the function on the class if it is
+  // not found in the ICData.
   if (!function.IsNull()) {
+    const ICData& new_ic_data = ICData::ZoneHandle(ICData::New(
+        Function::Handle(ic_data.function()),
+        String::Handle(ic_data.target_name()),
+        Object::empty_array(),  // Dummy argument descriptor.
+        ic_data.deopt_id(),
+        ic_data.num_args_tested()));
+    new_ic_data.set_deopt_reason(ic_data.deopt_reason());
     new_ic_data.AddReceiverCheck(cid, function);
+    return new_ic_data;
   }
 
-  return new_ic_data;
+  return ic_data;
 }
 
 
 void FlowGraphOptimizer::SpecializePolymorphicInstanceCall(
     PolymorphicInstanceCallInstr* call) {
   if (!call->with_checks()) {
     return;  // Already specialized.
   }
 
   const intptr_t receiver_cid =
       call->PushArgumentAt(0)->value()->Type()->ToCid();
   if (receiver_cid == kDynamicCid) {
     return;  // No information about receiver was infered.
   }
 
-  const ICData& ic_data = SpecializeICData(call->ic_data(), receiver_cid);
+  const ICData& ic_data = TrySpecializeICData(call->ic_data(), receiver_cid);
+  if (ic_data.raw() == call->ic_data().raw()) {
+    // No specialization.
+    return;
+  }
 
   const bool with_checks = false;
   PolymorphicInstanceCallInstr* specialized =
       new PolymorphicInstanceCallInstr(call->instance_call(),
                                        ic_data,
                                        with_checks);
   call->ReplaceWith(specialized, current_iterator());
 }
 
 
@@ skipping 8085 matching lines @@
   }
 
   // Insert materializations at environment uses.
   for (intptr_t i = 0; i < exits.length(); i++) {
     CreateMaterializationAt(exits[i], alloc, alloc->cls(), *fields);
   }
 }
 
 
 }  // namespace dart