Remove superfluous HInnerAllocatedObject in BuildEmitDeepCopy

src/hydrogen.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 9988 matching lines @@
 
   // Copy object elements if non-COW.
   HValue* object_elements = BuildEmitObjectHeader(boilerplate_object, target,
       data_target, object_offset, elements_offset, elements_size);
   if (object_elements != NULL) {
     BuildEmitElements(elements, original_elements, kind, object_elements,
         target, offset, data_target, data_offset);
   }
 
   // Copy in-object properties.
-  HValue* object_properties =
-      AddInstruction(new(zone) HInnerAllocatedObject(target, object_offset));
-  BuildEmitInObjectProperties(boilerplate_object, original_boilerplate_object,
-      object_properties, target, offset, data_target, data_offset);
+  if (boilerplate_object->map()->NumberOfFields() != 0) {
+    HValue* object_properties =
+        AddInstruction(new(zone) HInnerAllocatedObject(target, object_offset));
+    BuildEmitInObjectProperties(boilerplate_object, original_boilerplate_object,
+        object_properties, target, offset, data_target, data_offset);
+  }
 
   // Create allocation site info.
   if (mode == TRACK_ALLOCATION_SITE &&
       boilerplate_object->map()->CanTrackAllocationSite()) {
     elements_offset += AllocationSiteInfo::kSize;
     *offset += AllocationSiteInfo::kSize;
     HInstruction* original_boilerplate = AddInstruction(new(zone) HConstant(
         original_boilerplate_object));
     BuildCreateAllocationSiteInfo(target, JSArray::kSize, original_boilerplate);
   }
@@ skipping 1515 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal