Avoid HeapObject check in HStoreNamedField.

src/hydrogen.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "hydrogen.h"
 
 #include <algorithm>
 
 #include "v8.h"
 #include "allocation-site-scopes.h"
@@ skipping 5487 matching lines @@
     } else {
       // Already holds a HeapNumber; load the box and write its value field.
       HInstruction* heap_number = Add<HLoadNamedField>(
           checked_object, static_cast<HValue*>(NULL), heap_number_access);
       heap_number->set_type(HType::HeapNumber());
       instr = New<HStoreNamedField>(heap_number,
                                     HObjectAccess::ForHeapNumberValue(),
                                     value, STORE_TO_INITIALIZED_ENTRY);
     }
   } else {
+    if (field_access.representation().IsHeapObject()) {
+      BuildCheckHeapObject(value);
+    }
+
     if (!info->field_maps()->is_empty()) {
       ASSERT(field_access.representation().IsHeapObject());
-      BuildCheckHeapObject(value);
       value = Add<HCheckMaps>(value, info->field_maps());
-
-      // TODO(bmeurer): This is a dirty hack to avoid repeating the smi check
-      // that was already performed by the HCheckHeapObject above in the
-      // HStoreNamedField below. We should really do this right instead and
-      // make Crankshaft aware of Representation::HeapObject().
-      field_access = field_access.WithRepresentation(Representation::Tagged());
     }
 
     // This is a normal store.
     instr = New<HStoreNamedField>(
         checked_object->ActualValue(), field_access, value,
         transition_to_field ? INITIALIZING_STORE : STORE_TO_INITIALIZED_ENTRY);
   }
 
   if (transition_to_field) {
     Handle<Map> transition(info->transition());
@@ skipping 6285 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal