[heap] Isolate read-only space creation

This provides a single point where read-only space sharing will be
controlled. Eventually ReadOnlyDeserializer will take ReadOnlyHeap
instead of Isolate, first steps include
https://chromium-review.googlesource.com/c/v8/v8/+/1483054

Bug: v8:7464
Change-Id: I213819aeca6fca335235025c9195edf474230eda
Reviewed-on: https://chromium-review.googlesource.com/c/1489087
Commit-Queue: Maciej Goszczycki <goszczycki@google.com>
Reviewed-by: Dan Elphick <delphick@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59954}

BUILD.gn

@@ -2108,6 +2108,8 @@ v8_source_set("v8_base") {
     "src/heap/objects-visiting-inl.h",
     "src/heap/objects-visiting.cc",
     "src/heap/objects-visiting.h",
+    "src/heap/read-only-heap.cc",
+    "src/heap/read-only-heap.h",
     "src/heap/remembered-set.h",
     "src/heap/scavenge-job.cc",
     "src/heap/scavenge-job.h",

src/DEPS

@@ -15,6 +15,7 @@ include_rules = [
   "+src/heap/heap-inl.h",
   "+src/heap/heap-write-barrier-inl.h",
   "+src/heap/heap-write-barrier.h",
+  "+src/heap/read-only-heap.h",
   "-src/inspector",
   "-src/interpreter",
   "+src/interpreter/bytecode-array-accessor.h",

src/api.cc

@@ -584,7 +584,7 @@ SnapshotCreator::SnapshotCreator(Isolate* isolate,
     internal_isolate->set_snapshot_blob(blob);
     i::Snapshot::Initialize(internal_isolate);
   } else {
-    internal_isolate->Init(nullptr);
+    internal_isolate->InitWithoutSnapshot();
   }
   data_ = data;
 }
@@ -8209,7 +8209,7 @@ void Isolate::Initialize(Isolate* isolate,
     }
     base::ElapsedTimer timer;
     if (i::FLAG_profile_deserialization) timer.Start();
-    i_isolate->Init(nullptr);
+    i_isolate->InitWithoutSnapshot();
     if (i::FLAG_profile_deserialization) {
       double ms = timer.Elapsed().InMillisecondsF();
       i::PrintF("[Initializing isolate from scratch took %0.3f ms]\n", ms);

src/globals.h

@@ -663,6 +663,8 @@ enum AllocationSpace {
 
   FIRST_SPACE = RO_SPACE,
   LAST_SPACE = NEW_LO_SPACE,
+  FIRST_MUTABLE_SPACE = NEW_SPACE,
+  LAST_MUTABLE_SPACE = NEW_LO_SPACE,
   FIRST_GROWABLE_PAGED_SPACE = OLD_SPACE,
   LAST_GROWABLE_PAGED_SPACE = MAP_SPACE
 };

src/heap/heap.cc

@@ -37,6 +37,7 @@
 #include "src/heap/object-stats.h"
 #include "src/heap/objects-visiting-inl.h"
 #include "src/heap/objects-visiting.h"
+#include "src/heap/read-only-heap.h"
 #include "src/heap/remembered-set.h"
 #include "src/heap/scavenge-job.h"
 #include "src/heap/scavenger-inl.h"
@@ -4493,7 +4494,7 @@ HeapObject Heap::AllocateRawCodeInLargeObjectSpace(int size) {
   return HeapObject();
 }
 
-void Heap::SetUp() {
+void Heap::SetUp(ReadOnlyHeap* ro_heap) {
 #ifdef V8_ENABLE_ALLOCATION_TIMEOUT
   allocation_timeout_ = NextAllocationTimeout();
 #endif
@@ -4506,6 +4507,9 @@ void Heap::SetUp() {
   // and old_generation_size_ otherwise.
   if (!configured_) ConfigureHeapDefault();
 
+  DCHECK_NOT_NULL(ro_heap);
+  read_only_heap_ = ro_heap;
+
   mmap_region_base_ =
       reinterpret_cast<uintptr_t>(v8::internal::GetRandomMmapAddr()) &
       ~kMmapRegionMask;
@@ -4541,7 +4545,8 @@ void Heap::SetUp() {
     space_[i] = nullptr;
   }
 
-  space_[RO_SPACE] = read_only_space_ = new ReadOnlySpace(this);
+  space_[RO_SPACE] = read_only_space_ = ro_heap->read_only_space();
+  DCHECK_NOT_NULL(read_only_space_);
   space_[NEW_SPACE] = new_space_ =
       new NewSpace(this, memory_allocator_->data_page_allocator(),
                    initial_semispace_size_, max_semi_space_size_);
@@ -4818,7 +4823,9 @@ void Heap::TearDown() {
 
   tracer_.reset();
 
-  for (int i = FIRST_SPACE; i <= LAST_SPACE; i++) {
+  read_only_heap_->OnHeapTearDown();
+  space_[RO_SPACE] = read_only_space_ = nullptr;
+  for (int i = FIRST_MUTABLE_SPACE; i <= LAST_MUTABLE_SPACE; i++) {
     delete space_[i];
     space_[i] = nullptr;
   }

src/heap/heap.h

@@ -76,6 +76,7 @@ class ObjectIterator;
 class ObjectStats;
 class Page;
 class PagedSpace;
+class ReadOnlyHeap;
 class RootVisitor;
 class ScavengeJob;
 class Scavenger;
@@ -579,7 +580,7 @@ class Heap {
 
   // Prepares the heap, setting up memory areas that are needed in the isolate
   // without actually creating any objects.
-  void SetUp();
+  void SetUp(ReadOnlyHeap* ro_heap);
 
   // (Re-)Initialize hash seed from flag or RNG.
   void InitializeHashSeed();
@@ -625,6 +626,8 @@ class Heap {
   // Getters to other components. ==============================================
   // ===========================================================================
 
+  ReadOnlyHeap* read_only_heap() const { return read_only_heap_; }
+
   GCTracer* tracer() { return tracer_.get(); }
 
   MemoryAllocator* memory_allocator() { return memory_allocator_.get(); }
@@ -1788,6 +1791,8 @@ class Heap {
   // and after context disposal.
   int number_of_disposed_maps_ = 0;
 
+  ReadOnlyHeap* read_only_heap_ = nullptr;
+
   NewSpace* new_space_ = nullptr;
   OldSpace* old_space_ = nullptr;
   CodeSpace* code_space_ = nullptr;

src/heap/read-only-heap.cc

+// Copyright 2019 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/read-only-heap.h"
+
+#include "src/heap/spaces.h"
+
+namespace v8 {
+namespace internal {
+
+// static
+ReadOnlyHeap* ReadOnlyHeap::GetOrCreateReadOnlyHeap(Heap* heap) {
+  return new ReadOnlyHeap(new ReadOnlySpace(heap));
+}
+
+void ReadOnlyHeap::MaybeDeserialize(Isolate* isolate,
+                                    ReadOnlyDeserializer* des) {
+  des->DeserializeInto(isolate);
+}
+
+void ReadOnlyHeap::OnHeapTearDown() {
+  delete read_only_space_;
+  delete this;
+}
+
+}  // namespace internal
+}  // namespace v8

src/heap/read-only-heap.h

+// Copyright 2019 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.
+
+#ifndef V8_HEAP_READ_ONLY_HEAP_H_
+#define V8_HEAP_READ_ONLY_HEAP_H_
+
+#include "src/base/macros.h"
+#include "src/heap/heap.h"
+#include "src/roots.h"
+#include "src/snapshot/read-only-deserializer.h"
+
+namespace v8 {
+namespace internal {
+
+class ReadOnlySpace;
+
+// This class transparently manages read-only space, roots and cache creation
+// and destruction. Eventually this will allow sharing these artifacts between
+// isolates.
+class ReadOnlyHeap {
+ public:
+  static ReadOnlyHeap* GetOrCreateReadOnlyHeap(Heap* heap);
+  // If necessary, deserialize read-only objects and set up read-only object
+  // cache.
+  void MaybeDeserialize(Isolate* isolate, ReadOnlyDeserializer* des);
+  // Frees ReadOnlySpace and itself when sharing is disabled. No-op otherwise.
+  // Read-only data should not be used within the current isolate after this is
+  // called.
+  void OnHeapTearDown();
+
+  std::vector<Object>* read_only_object_cache() {
+    return &read_only_object_cache_;
+  }
+  ReadOnlySpace* read_only_space() const { return read_only_space_; }
+
+ private:
+  ReadOnlySpace* read_only_space_ = nullptr;
+  std::vector<Object> read_only_object_cache_;
+
+  explicit ReadOnlyHeap(ReadOnlySpace* ro_space) : read_only_space_(ro_space) {}
+  DISALLOW_COPY_AND_ASSIGN(ReadOnlyHeap);
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_HEAP_READ_ONLY_HEAP_H_

src/heap/spaces.h

@@ -1436,14 +1436,14 @@ class V8_EXPORT_PRIVATE MemoryAllocator {
 
   Unmapper* unmapper() { return &unmapper_; }
 
- private:
-  void InitializeCodePageAllocator(v8::PageAllocator* page_allocator,
-                                   size_t requested);
-
   // PreFree logically frees the object, i.e., it takes care of the size
   // bookkeeping and calls the allocation callback.
   void PreFreeMemory(MemoryChunk* chunk);
 
+ private:
+  void InitializeCodePageAllocator(v8::PageAllocator* page_allocator,
+                                   size_t requested);
+
   // FreeMemory can be called concurrently when PreFree was executed before.
   void PerformFreeMemory(MemoryChunk* chunk);
 

src/isolate.cc

@@ -37,6 +37,7 @@
 #include "src/frames-inl.h"
 #include "src/hash-seed-inl.h"
 #include "src/heap/heap-inl.h"
+#include "src/heap/read-only-heap.h"
 #include "src/ic/stub-cache.h"
 #include "src/interpreter/interpreter.h"
 #include "src/isolate-inl.h"
@@ -64,6 +65,7 @@
 #include "src/simulator.h"
 #include "src/snapshot/embedded-data.h"
 #include "src/snapshot/embedded-file-writer.h"
+#include "src/snapshot/read-only-deserializer.h"
 #include "src/snapshot/startup-deserializer.h"
 #include "src/string-stream.h"
 #include "src/tracing/tracing-category-observer.h"
@@ -3262,11 +3264,24 @@ void Isolate::TearDownEmbeddedBlob() {
   }
 }
 
-bool Isolate::Init(StartupDeserializer* des) {
+bool Isolate::InitWithoutSnapshot() { return Init(nullptr, nullptr); }
+
+bool Isolate::InitWithSnapshot(ReadOnlyDeserializer* read_only_deserializer,
+                               StartupDeserializer* startup_deserializer) {
+  DCHECK_NOT_NULL(read_only_deserializer);
+  DCHECK_NOT_NULL(startup_deserializer);
+  return Init(read_only_deserializer, startup_deserializer);
+}
+
+bool Isolate::Init(ReadOnlyDeserializer* read_only_deserializer,
+                   StartupDeserializer* startup_deserializer) {
   TRACE_ISOLATE(init);
+  const bool create_heap_objects = (read_only_deserializer == nullptr);
+  // We either have both or neither.
+  DCHECK_EQ(create_heap_objects, startup_deserializer == nullptr);
 
   base::ElapsedTimer timer;
-  if (des == nullptr && FLAG_profile_deserialization) timer.Start();
+  if (create_heap_objects && FLAG_profile_deserialization) timer.Start();
 
   time_millis_at_init_ = heap_.MonotonicallyIncreasingTimeInMs();
 
@@ -3320,7 +3335,8 @@ bool Isolate::Init(StartupDeserializer* des) {
 
   // SetUp the object heap.
   DCHECK(!heap_.HasBeenSetUp());
-  heap_.SetUp();
+  auto* read_only_heap = ReadOnlyHeap::GetOrCreateReadOnlyHeap(&heap_);
+  heap_.SetUp(read_only_heap);
 
   isolate_data_.external_reference_table()->Init(this);
 
@@ -3332,7 +3348,6 @@ bool Isolate::Init(StartupDeserializer* des) {
 
   deoptimizer_data_ = new DeoptimizerData(heap());
 
-  const bool create_heap_objects = (des == nullptr);
   if (setup_delegate_ == nullptr) {
     setup_delegate_ = new SetupIsolateDelegate(create_heap_objects);
   }
@@ -3404,7 +3419,10 @@ bool Isolate::Init(StartupDeserializer* des) {
     AlwaysAllocateScope always_allocate(this);
     CodeSpaceMemoryModificationScope modification_scope(&heap_);
 
-    if (!create_heap_objects) des->DeserializeInto(this);
+    if (!create_heap_objects) {
+      read_only_heap->MaybeDeserialize(this, read_only_deserializer);
+      startup_deserializer->DeserializeInto(this);
+    }
     load_stub_cache_->Initialize();
     store_stub_cache_->Initialize();
     interpreter_->Initialize();
@@ -3463,7 +3481,7 @@ bool Isolate::Init(StartupDeserializer* des) {
     ast_string_constants_ = new AstStringConstants(this, HashSeed(this));
   }
 
-  initialized_from_snapshot_ = (des != nullptr);
+  initialized_from_snapshot_ = !create_heap_objects;
 
   if (!FLAG_inline_new) heap_.DisableInlineAllocation();
 
@@ -3476,7 +3494,7 @@ bool Isolate::Init(StartupDeserializer* des) {
                                                sampling_flags);
   }
 
-  if (des == nullptr && FLAG_profile_deserialization) {
+  if (create_heap_objects && FLAG_profile_deserialization) {
     double ms = timer.Elapsed().InMillisecondsF();
     PrintF("[Initializing isolate from scratch took %0.3f ms]\n", ms);
   }
@@ -3484,7 +3502,6 @@ bool Isolate::Init(StartupDeserializer* des) {
   return true;
 }
 
-
 void Isolate::Enter() {
   Isolate* current_isolate = nullptr;
   PerIsolateThreadData* current_data = CurrentPerIsolateThreadData();

src/isolate.h

@@ -84,6 +84,7 @@ class MaterializedObjectStore;
 class Microtask;
 class MicrotaskQueue;
 class OptimizingCompileDispatcher;
+class ReadOnlyDeserializer;
 class RegExpStack;
 class RootVisitor;
 class RuntimeProfiler;
@@ -518,7 +519,9 @@ class Isolate final : private HiddenFactory {
   void InitializeLoggingAndCounters();
   bool InitializeCounters();  // Returns false if already initialized.
 
-  bool Init(StartupDeserializer* des);
+  bool InitWithoutSnapshot();
+  bool InitWithSnapshot(ReadOnlyDeserializer* read_only_deserializer,
+                        StartupDeserializer* startup_deserializer);
 
   // True if at least one thread Enter'ed this isolate.
   bool IsInUse() { return entry_stack_ != nullptr; }
@@ -1349,10 +1352,6 @@ class Isolate final : private HiddenFactory {
   void AddDetachedContext(Handle<Context> context);
   void CheckDetachedContextsAfterGC();
 
-  std::vector<Object>* read_only_object_cache() {
-    return &read_only_object_cache_;
-  }
-
   std::vector<Object>* partial_snapshot_cache() {
     return &partial_snapshot_cache_;
   }
@@ -1498,6 +1497,9 @@ class Isolate final : private HiddenFactory {
   explicit Isolate(std::unique_ptr<IsolateAllocator> isolate_allocator);
   ~Isolate();
 
+  bool Init(ReadOnlyDeserializer* read_only_deserializer,
+            StartupDeserializer* startup_deserializer);
+
   void CheckIsolateLayout();
 
   class ThreadDataTable {
@@ -1751,7 +1753,6 @@ class Isolate final : private HiddenFactory {
 
   v8::Isolate::UseCounterCallback use_counter_callback_ = nullptr;
 
-  std::vector<Object> read_only_object_cache_;
   std::vector<Object> partial_snapshot_cache_;
 
   // Used during builtins compilation to build the builtins constants table,

src/snapshot/deserializer.cc

@@ -7,6 +7,7 @@
 #include "src/assembler-inl.h"
 #include "src/heap/heap-inl.h"
 #include "src/heap/heap-write-barrier-inl.h"
+#include "src/heap/read-only-heap.h"
 #include "src/interpreter/interpreter.h"
 #include "src/isolate.h"
 #include "src/log.h"
@@ -794,8 +795,9 @@ TSlot Deserializer::ReadDataCase(Isolate* isolate, TSlot current,
     hot_objects_.Add(heap_object);
   } else if (bytecode == kReadOnlyObjectCache) {
     int cache_index = source_.GetInt();
-    heap_object =
-        HeapObject::cast(isolate->read_only_object_cache()->at(cache_index));
+    heap_object = HeapObject::cast(
+        isolate->heap()->read_only_heap()->read_only_object_cache()->at(
+            cache_index));
     DCHECK(!Heap::InYoungGeneration(heap_object));
     emit_write_barrier = false;
   } else if (bytecode == kPartialSnapshotCache) {

src/snapshot/read-only-deserializer.cc

@@ -6,6 +6,7 @@
 
 #include "src/api.h"
 #include "src/heap/heap-inl.h"  // crbug.com/v8/8499
+#include "src/heap/read-only-heap.h"
 #include "src/objects/slots.h"
 #include "src/snapshot/snapshot.h"
 #include "src/v8threads.h"
@@ -25,19 +26,24 @@ void ReadOnlyDeserializer::DeserializeInto(Isolate* isolate) {
   // No active handles.
   DCHECK(isolate->handle_scope_implementer()->blocks()->empty());
   // Partial snapshot cache is not yet populated.
-  DCHECK(isolate->read_only_object_cache()->empty());
+  DCHECK(isolate->heap()->read_only_heap()->read_only_object_cache()->empty());
   DCHECK(isolate->partial_snapshot_cache()->empty());
   // Builtins are not yet created.
   DCHECK(!isolate->builtins()->is_initialized());
 
   {
     DisallowHeapAllocation no_gc;
+    ReadOnlyRoots roots(isolate);
 
-    ReadOnlyRoots(isolate).Iterate(this);
-    isolate->heap()->read_only_space()->RepairFreeListsAfterDeserialization();
+    roots.Iterate(this);
+    isolate->heap()
+        ->read_only_heap()
+        ->read_only_space()
+        ->RepairFreeListsAfterDeserialization();
 
     // Deserialize the Read-only Object Cache.
-    std::vector<Object>* cache = isolate->read_only_object_cache();
+    std::vector<Object>* cache =
+        isolate->heap()->read_only_heap()->read_only_object_cache();
     for (size_t i = 0;; ++i) {
       // Extend the array ready to get a value when deserializing.
       if (cache->size() <= i) cache->push_back(Smi::kZero);
@@ -45,15 +51,15 @@ void ReadOnlyDeserializer::DeserializeInto(Isolate* isolate) {
       // cache and eventually terminates the cache with undefined.
       VisitRootPointer(Root::kReadOnlyObjectCache, nullptr,
                        FullObjectSlot(&cache->at(i)));
-      if (cache->at(i)->IsUndefined(isolate)) break;
+      if (cache->at(i)->IsUndefined(roots)) break;
     }
     DeserializeDeferredObjects();
   }
-}
 
-void ReadOnlyDeserializer::RehashHeap() {
-  DCHECK(FLAG_rehash_snapshot && can_rehash());
-  Rehash();
+  if (FLAG_rehash_snapshot && can_rehash()) {
+    isolate_->heap()->InitializeHashSeed();
+    Rehash();
+  }
 }
 
 }  // namespace internal

src/snapshot/read-only-deserializer.h

@@ -20,12 +20,6 @@ class ReadOnlyDeserializer final : public Deserializer {
 
   // Deserialize the snapshot into an empty heap.
   void DeserializeInto(Isolate* isolate);
-
- private:
-  friend class StartupDeserializer;
-
-  // Rehash after deserializing.
-  void RehashHeap();
 };
 
 }  // namespace internal

src/snapshot/snapshot-common.cc

@@ -9,6 +9,7 @@
 #include "src/base/platform/platform.h"
 #include "src/counters.h"
 #include "src/snapshot/partial-deserializer.h"
+#include "src/snapshot/read-only-deserializer.h"
 #include "src/snapshot/startup-deserializer.h"
 #include "src/version.h"
 
@@ -44,10 +45,12 @@ bool Snapshot::Initialize(Isolate* isolate) {
   SnapshotData startup_snapshot_data(startup_data);
   Vector<const byte> read_only_data = ExtractReadOnlyData(blob);
   SnapshotData read_only_snapshot_data(read_only_data);
-  StartupDeserializer deserializer(&startup_snapshot_data,
-                                   &read_only_snapshot_data);
-  deserializer.SetRehashability(ExtractRehashability(blob));
-  bool success = isolate->Init(&deserializer);
+  StartupDeserializer startup_deserializer(&startup_snapshot_data);
+  ReadOnlyDeserializer read_only_deserializer(&read_only_snapshot_data);
+  startup_deserializer.SetRehashability(ExtractRehashability(blob));
+  read_only_deserializer.SetRehashability(ExtractRehashability(blob));
+  bool success =
+      isolate->InitWithSnapshot(&read_only_deserializer, &startup_deserializer);
   if (FLAG_profile_deserialization) {
     double ms = timer.Elapsed().InMillisecondsF();
     int bytes = startup_data.length();

src/snapshot/snapshot.h

@@ -67,6 +67,7 @@ class Snapshot : public AllStatic {
   // ---------------- Helper methods ----------------
 
   static bool HasContextSnapshot(Isolate* isolate, size_t index);
+  static bool EmbedsScript(Isolate* isolate);
 
   // To be implemented by the snapshot source.
   static const v8::StartupData* DefaultSnapshotBlob();

src/snapshot/startup-deserializer.cc

@@ -7,7 +7,6 @@
 #include "src/api.h"
 #include "src/assembler-inl.h"
 #include "src/heap/heap-inl.h"
-#include "src/snapshot/read-only-deserializer.h"
 #include "src/snapshot/snapshot.h"
 #include "src/v8threads.h"
 
@@ -17,10 +16,6 @@ namespace internal {
 void StartupDeserializer::DeserializeInto(Isolate* isolate) {
   Initialize(isolate);
 
-  ReadOnlyDeserializer read_only_deserializer(read_only_data_);
-  read_only_deserializer.SetRehashability(can_rehash());
-  read_only_deserializer.DeserializeInto(isolate);
-
   if (!allocator()->ReserveSpace()) {
     V8::FatalProcessOutOfMemory(isolate, "StartupDeserializer");
   }
@@ -64,8 +59,7 @@ void StartupDeserializer::DeserializeInto(Isolate* isolate) {
   LogNewMapEvents();
 
   if (FLAG_rehash_snapshot && can_rehash()) {
-    isolate->heap()->InitializeHashSeed();
-    read_only_deserializer.RehashHeap();
+    // Hash seed was initalized in ReadOnlyDeserializer.
     Rehash();
   }
 }

src/snapshot/startup-deserializer.h

@@ -14,9 +14,8 @@ namespace internal {
 // Initializes an isolate with context-independent data from a given snapshot.
 class StartupDeserializer final : public Deserializer {
  public:
-  StartupDeserializer(const SnapshotData* startup_data,
-                      const SnapshotData* read_only_data)
-      : Deserializer(startup_data, false), read_only_data_(read_only_data) {}
+  explicit StartupDeserializer(const SnapshotData* startup_data)
+      : Deserializer(startup_data, false) {}
 
   // Deserialize the snapshot into an empty heap.
   void DeserializeInto(Isolate* isolate);
@@ -24,8 +23,6 @@ class StartupDeserializer final : public Deserializer {
  private:
   void FlushICache();
   void LogNewMapEvents();
-
-  const SnapshotData* read_only_data_;
 };
 
 }  // namespace internal

test/cctest/test-serialize.cc

@@ -51,6 +51,7 @@
 #include "src/snapshot/natives.h"
 #include "src/snapshot/partial-deserializer.h"
 #include "src/snapshot/partial-serializer.h"
+#include "src/snapshot/read-only-deserializer.h"
 #include "src/snapshot/read-only-serializer.h"
 #include "src/snapshot/snapshot.h"
 #include "src/snapshot/startup-deserializer.h"
@@ -92,7 +93,7 @@ class TestSerializer {
     v8::Isolate* v8_isolate = NewIsolate(kEnableSerializer, kGenerateHeap);
     v8::Isolate::Scope isolate_scope(v8_isolate);
     i::Isolate* isolate = reinterpret_cast<i::Isolate*>(v8_isolate);
-    isolate->Init(nullptr);
+    isolate->Init(nullptr, nullptr);
     isolate->heap()->read_only_space()->ClearStringPaddingIfNeeded();
     return v8_isolate;
   }
@@ -100,13 +101,14 @@ class TestSerializer {
   static v8::Isolate* NewIsolateFromBlob(StartupBlobs& blobs) {
     SnapshotData startup_snapshot(blobs.startup);
     SnapshotData read_only_snapshot(blobs.read_only);
-    StartupDeserializer deserializer(&startup_snapshot, &read_only_snapshot);
+    ReadOnlyDeserializer read_only_deserializer(&read_only_snapshot);
+    StartupDeserializer startup_deserializer(&startup_snapshot);
     const bool kEnableSerializer = false;
     const bool kGenerateHeap = false;
     v8::Isolate* v8_isolate = NewIsolate(kEnableSerializer, kGenerateHeap);
     v8::Isolate::Scope isolate_scope(v8_isolate);
     i::Isolate* isolate = reinterpret_cast<i::Isolate*>(v8_isolate);
-    isolate->Init(&deserializer);
+    isolate->Init(&read_only_deserializer, &startup_deserializer);
     return v8_isolate;
   }