[serializer] ensure that immortal immovable roots are correctly deserialized.

src/heap/heap.cc

 // Copyright 2012 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 "src/heap/heap.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/ast/scopeinfo.h"
 #include "src/base/bits.h"
@@ skipping 4719 matching lines @@
   // Acquire execution access since we are going to read stack limit values.
   ExecutionAccess access(isolate());
   v->VisitPointers(&roots_[kSmiRootsStart], &roots_[kRootListLength]);
   v->Synchronize(VisitorSynchronization::kSmiRootList);
 }
 
 
 void Heap::IterateStrongRoots(ObjectVisitor* v, VisitMode mode) {
   v->VisitPointers(&roots_[0], &roots_[kStrongRootListLength]);
   v->Synchronize(VisitorSynchronization::kStrongRootList);
+  // The serializer/deserializer iterates the root list twice, first to pick
+  // off immortal immovable roots to make sure they end up on the first page,
+  // and then again for the rest.
+  if (mode == VISIT_ONLY_STRONG_ROOT_LIST) return;
 
   isolate_->bootstrapper()->Iterate(v);
   v->Synchronize(VisitorSynchronization::kBootstrapper);
   isolate_->Iterate(v);
   v->Synchronize(VisitorSynchronization::kTop);
   Relocatable::Iterate(isolate_, v);
   v->Synchronize(VisitorSynchronization::kRelocatable);
 
   isolate_->compilation_cache()->Iterate(v);
   v->Synchronize(VisitorSynchronization::kCompilationCache);
 
   // Iterate over local handles in handle scopes.
   isolate_->handle_scope_implementer()->Iterate(v);
   isolate_->IterateDeferredHandles(v);
   v->Synchronize(VisitorSynchronization::kHandleScope);
 
   // Iterate over the builtin code objects and code stubs in the
   // heap. Note that it is not necessary to iterate over code objects
   // on scavenge collections.
   if (mode != VISIT_ALL_IN_SCAVENGE) {
     isolate_->builtins()->IterateBuiltins(v);
     v->Synchronize(VisitorSynchronization::kBuiltins);
     isolate_->interpreter()->IterateDispatchTable(v);
     v->Synchronize(VisitorSynchronization::kDispatchTable);
   }
 
   // Iterate over global handles.
   switch (mode) {
+    case VISIT_ONLY_STRONG_ROOT_LIST:
+      UNREACHABLE();
+      break;
     case VISIT_ONLY_STRONG:
     case VISIT_ONLY_STRONG_FOR_SERIALIZATION:
       isolate_->global_handles()->IterateStrongRoots(v);
       break;
     case VISIT_ALL_IN_SCAVENGE:
       isolate_->global_handles()->IterateNewSpaceStrongAndDependentRoots(v);
       break;
     case VISIT_ALL_IN_SWEEP_NEWSPACE:
     case VISIT_ALL:
       isolate_->global_handles()->IterateAllRoots(v);
@@ skipping 1621 matching lines @@
 }
 
 
 // static
 int Heap::GetStaticVisitorIdForMap(Map* map) {
   return StaticVisitorBase::GetVisitorId(map);
 }
 
 }  // namespace internal
 }  // namespace v8