If a PolymorphicInstanceCall has a single target, ..

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 520 matching lines @@
       return;
     }
     if ((op_kind == Token::kSET) && TryInlineInstanceSetter(instr, comp)) {
       return;
     }
     if (TryInlineInstanceMethod(instr, comp)) {
       return;
     }
     const intptr_t kMaxChecks = 4;
     if (comp->ic_data()->NumberOfChecks() <= kMaxChecks) {
-      PolymorphicInstanceCallComp* call = new PolymorphicInstanceCallComp(comp);
       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);
+        InsertCheckBefore(instr, check, instr->env()->Copy());
+        // 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);
     }
   }
   // An instance call without ICData should continue calling via IC calls
   // which should trigger reoptimization of optimized code.
 }
 
 
 void FlowGraphOptimizer::VisitStaticCall(StaticCallComp* comp,
@@ skipping 417 matching lines @@
         OS::Print("Replacing v%d with v%d\n",
                   instr->ssa_temp_index(),
                   result->ssa_temp_index());
       }
     }
   }
 }
 
 
 }  // namespace dart