To diagnose chromium bug 284577, some additional CHECKS. TODOs are

src/hydrogen.cc

 // Copyright 2013 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 1806 matching lines @@
     }
   }
 
   if_nil.CaptureContinuation(continuation);
 }
 
 
 HValue* HGraphBuilder::BuildCreateAllocationMemento(HValue* previous_object,
                                                     int previous_object_size,
                                                     HValue* alloc_site) {
-  ASSERT(alloc_site != NULL);
+  // TODO(mvstanton): ASSERT altered to CHECK to diagnose chromium bug 284577
+  CHECK(alloc_site != NULL);
   HInnerAllocatedObject* alloc_memento = Add<HInnerAllocatedObject>(
       previous_object, previous_object_size);
   Handle<Map> alloc_memento_map(
       isolate()->heap()->allocation_memento_map());
   AddStoreMapConstant(alloc_memento, alloc_memento_map);
   HObjectAccess access = HObjectAccess::ForAllocationMementoSite();
   Add<HStoreNamedField>(alloc_memento, access, alloc_site);
+  // TODO(mvstanton): to diagnose chromium bug 284577 we could/should
+  // dereference the alloc_site here. We could do a map check. However it has
+  // a performance impact so I'm not doing that right away.
+  // for example, something like:
+  // Add<HLoadNamedField>(alloc_site,
+  //                      HObjectAccess::ForAllocationSiteTransitionInfo());

[Hannes Payer (out of office), 2013/09/11 13:25:35]

I guess you are planing to land this in a different CL, remove this code here.

   return alloc_memento;
 }
 
 
 HInstruction* HGraphBuilder::BuildGetNativeContext() {
   // Get the global context, then the native context
   HInstruction* global_object = Add<HGlobalObject>();
   HObjectAccess access = HObjectAccess::ForJSObjectOffset(
       GlobalObject::kNativeContextOffset);
   return Add<HLoadNamedField>(global_object, access);
@@ skipping 7834 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal