Factored out code, based on Florian's recent submit.

runtime/vm/flow_graph_optimizer.cc

 // 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.
 
 #include "vm/flow_graph_optimizer.h"
 
 #include "vm/cha.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/hash_map.h"
 #include "vm/il_printer.h"
@@ skipping 589 matching lines @@
       return;
     }
     const intptr_t kMaxChecks = 4;
     if (comp->ic_data()->NumberOfChecks() <= kMaxChecks) {
       const ICData& unary_checks =
           ICData::ZoneHandle(comp->ic_data()->AsUnaryClassChecks());
       bool call_with_checks;
       // TODO(srdjan): Add check class comp for mixed smi/non-smi.
       if (HasOneTarget(unary_checks) &&
           (unary_checks.GetReceiverClassIdAt(0) != kSmiCid)) {
-        Value* value = comp->ArgumentAt(0)->value()->CopyValue();
         // Type propagation has not run yet, we cannot eliminate the check.
-        CheckClassComp* check = new CheckClassComp(value, comp);
-        check->set_ic_data(&unary_checks);
-        InsertBefore(instr, check, instr->env(), BindInstr::kUnused);
+        AddCheckClass(instr, comp, comp->ArgumentAt(0)->value()->CopyValue());
         // Call can still deoptimize, do not detach environment from instr.
         call_with_checks = false;
       } else {
         call_with_checks = true;
       }
       PolymorphicInstanceCallComp* call =
           new PolymorphicInstanceCallComp(comp, call_with_checks);
       call->set_ic_data(&unary_checks);
       instr->set_computation(call);
     }
@@ skipping 427 matching lines @@
       DirectChainedHashMap<BindInstr*> child_map(*map);  // Copy map.
       OptimizeRecursive(child, &child_map);
     } else {
       OptimizeRecursive(child, map);  // Reuse map for the last child.
     }
   }
 }
 
 
 }  // namespace dart