Do not visit smis in the root list during GC.

src/heap.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 5823 matching lines @@
 
 #ifdef VERIFY_HEAP
 void Heap::Verify() {
   CHECK(HasBeenSetUp());
 
   store_buffer()->Verify();
 
   VerifyPointersVisitor visitor;
   IterateRoots(&visitor, VISIT_ONLY_STRONG);
 
+  VerifySmisVisitor smis_visitor;
+  IterateRootSmis(&smis_visitor);
+
   new_space_.Verify();
 
   old_pointer_space_->Verify(&visitor);
   map_space_->Verify(&visitor);
 
   VerifyPointersVisitor no_dirty_regions_visitor;
   old_data_space_->Verify(&no_dirty_regions_visitor);
   code_space_->Verify(&no_dirty_regions_visitor);
   cell_space_->Verify(&no_dirty_regions_visitor);
   property_cell_space_->Verify(&no_dirty_regions_visitor);
@@ skipping 277 matching lines @@
   v->Synchronize(VisitorSynchronization::kStringTable);
   if (mode != VISIT_ALL_IN_SCAVENGE &&
       mode != VISIT_ALL_IN_SWEEP_NEWSPACE) {
     // Scavenge collections have special processing for this.
     external_string_table_.Iterate(v);
   }
   v->Synchronize(VisitorSynchronization::kExternalStringsTable);
 }
 
 
+void Heap::IterateRootSmis(ObjectVisitor* v) {
+  v->VisitPointers(&roots_[kRootSmisStart], &roots_[kRootListLength]);
+  v->Synchronize(VisitorSynchronization::kRootSmisList);
+}
+
+
 void Heap::IterateStrongRoots(ObjectVisitor* v, VisitMode mode) {
   v->VisitPointers(&roots_[0], &roots_[kStrongRootListLength]);
   v->Synchronize(VisitorSynchronization::kStrongRootList);
 
   v->VisitPointer(BitCast<Object**>(&hidden_string_));
   v->Synchronize(VisitorSynchronization::kInternalizedString);
 
   isolate_->bootstrapper()->Iterate(v);
   v->Synchronize(VisitorSynchronization::kBootstrapper);
   isolate_->Iterate(v);
@@ skipping 1569 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   CODE_AGE_LIST_COMPLETE(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   OS::MemCopy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   OS::MemCopy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 
 } }  // namespace v8::internal