Revert "[heap] Reduce size of possibly empty buckets"

This reverts commit 80caf2cf.

Reason for revert: Breaks gpu tests:
https://ci.chromium.org/p/v8/builders/ci/Win%20V8%20FYI%20Release%20(NVIDIA)/5570
# Debug check failed: !possibly_empty_buckets->Contains(bucket_index).

Original change's description:
> [heap] Reduce size of possibly empty buckets
> 
> Before this CL a byte was used per bucket to store whether the bucket
> is possibly empty or not. This CL changes this such that each bucket
> only needs a single bit.
> 
> PossiblyEmptyBuckets is now a word in the page header. If more bits
> are needed than fit into a single word, an external bitmap is
> allocated using AlignedAlloc. Storing this on the page header, allows
> to remove initial_buckets from the SlotSet. The SlotSet allocation is
> then again a power-of-2 in release mode.
> 
> Change-Id: If61fd5cfa153f98757beeb444a530f6e2803fdb6
> Bug: chromium:1023139
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1906376
> Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#64991}

TBR=ulan@chromium.org,dinfuehr@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: chromium:1023139
Change-Id: Ia90b07b9562af934dacba012da31e4f172f2922d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1918258Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65001}

src/heap/remembered-set.h

@@ -41,6 +41,20 @@ class RememberedSetOperations {
     return slots;
   }
 
+  template <typename Callback>
+  static int IterateAndTrackEmptyBuckets(
+      SlotSet* slot_set, MemoryChunk* chunk, Callback callback,
+      Worklist<MemoryChunk*, 64>::View empty_chunks) {
+    int slots = 0;
+    if (slot_set != nullptr) {
+      bool found_empty_bucket = false;
+      slots += slot_set->IterateAndTrackEmptyBuckets(
+          chunk->address(), chunk->buckets(), callback, &found_empty_bucket);
+      if (found_empty_bucket) empty_chunks.Push(chunk);
+    }
+    return slots;
+  }
+
   static void Remove(SlotSet* slot_set, MemoryChunk* chunk, Address slot_addr) {
     if (slot_set != nullptr) {
       uintptr_t offset = slot_addr - chunk->address();
@@ -154,16 +168,12 @@ class RememberedSet : public AllStatic {
   static int IterateAndTrackEmptyBuckets(
       MemoryChunk* chunk, Callback callback,
       Worklist<MemoryChunk*, 64>::View empty_chunks) {
-    SlotSet* slot_set = chunk->slot_set<type>();
-    int slots = 0;
-    if (slot_set != nullptr) {
-      PossiblyEmptyBuckets* possibly_empty_buckets =
-          chunk->possibly_empty_buckets();
-      slots += slot_set->IterateAndTrackEmptyBuckets(
-          chunk->address(), chunk->buckets(), callback, possibly_empty_buckets);
-      if (!possibly_empty_buckets->IsEmpty()) empty_chunks.Push(chunk);
-    }
-    return slots;
+    SlotSet* slots = chunk->slot_set<type>();
+    bool empty_bucket_found = false;
+    int slot_count = RememberedSetOperations::IterateAndTrackEmptyBuckets(
+        slots, chunk, callback, empty_chunks);
+    if (empty_bucket_found) empty_chunks.Push(chunk);
+    return slot_count;
   }
 
   static void FreeEmptyBuckets(MemoryChunk* chunk) {
@@ -178,8 +188,7 @@ class RememberedSet : public AllStatic {
     DCHECK(type == OLD_TO_NEW);
     SlotSet* slot_set = chunk->slot_set<type, AccessMode::NON_ATOMIC>();
     if (slot_set != nullptr &&
-        slot_set->CheckPossiblyEmptyBuckets(chunk->buckets(),
-                                            chunk->possibly_empty_buckets())) {
+        slot_set->CheckPossiblyEmptyBuckets(chunk->buckets())) {
       chunk->ReleaseSlotSet<type>();
       return true;
     }

src/heap/scavenger.cc

@@ -373,7 +373,9 @@ void ScavengerCollector::CollectGarbage() {
 #ifdef DEBUG
     RememberedSet<OLD_TO_NEW>::IterateMemoryChunks(
         heap_, [](MemoryChunk* chunk) {
-          DCHECK(chunk->possibly_empty_buckets()->IsEmpty());
+          SlotSet* slot_set = chunk->slot_set<OLD_TO_NEW>();
+          DCHECK_IMPLIES(slot_set != nullptr,
+                         slot_set->IsPossiblyEmptyCleared());
         });
 #endif
   }

src/heap/slot-set.h

@@ -23,105 +23,6 @@ namespace internal {
 
 enum SlotCallbackResult { KEEP_SLOT, REMOVE_SLOT };
 
-// Possibly empty buckets (buckets that do not contain any slots) are discovered
-// by the scavenger. Buckets might become non-empty when promoting objects later
-// or in another thread, so all those buckets need to be revisited.
-// Track possibly empty buckets within a SlotSet in this data structure. The
-// class contains a word-sized bitmap, in case more bits are needed the bitmap
-// is replaced with a pointer to a malloc-allocated bitmap.
-class PossiblyEmptyBuckets {
- public:
-  PossiblyEmptyBuckets() : bitmap_(kNullAddress) {}
-  PossiblyEmptyBuckets(PossiblyEmptyBuckets&& other) V8_NOEXCEPT
-      : bitmap_(other.bitmap_) {
-    other.bitmap_ = kNullAddress;
-  }
-
-  ~PossiblyEmptyBuckets() { Release(); }
-
-  void Initialize() {
-    bitmap_ = kNullAddress;
-    DCHECK(!IsAllocated());
-  }
-
-  void Release() {
-    if (IsAllocated()) {
-      AlignedFree(BitmapArray());
-    }
-    bitmap_ = kNullAddress;
-    DCHECK(!IsAllocated());
-  }
-
-  void Insert(size_t bucket_index, size_t buckets) {
-    if (IsAllocated()) {
-      InsertAllocated(bucket_index);
-    } else if (bucket_index + 1 < kBitsPerWord) {
-      bitmap_ |= static_cast<uintptr_t>(1) << (bucket_index + 1);
-    } else {
-      Allocate(buckets);
-      InsertAllocated(bucket_index);
-    }
-  }
-
-  bool Contains(size_t bucket_index) {
-    if (IsAllocated()) {
-      size_t word_idx = bucket_index / kBitsPerWord;
-      uintptr_t* word = BitmapArray() + word_idx;
-      return *word &
-             (static_cast<uintptr_t>(1) << (bucket_index % kBitsPerWord));
-    } else if (bucket_index + 1 < kBitsPerWord) {
-      return bitmap_ & (static_cast<uintptr_t>(1) << (bucket_index + 1));
-    } else {
-      return false;
-    }
-  }
-
-  bool IsEmpty() { return bitmap_ == kNullAddress; }
-
- private:
-  Address bitmap_;
-  static const Address kPointerTag = 1;
-  static const int kWordSize = sizeof(uintptr_t);
-  static const int kBitsPerWord = kWordSize * kBitsPerByte;
-
-  bool IsAllocated() { return bitmap_ & kPointerTag; }
-
-  void Allocate(size_t buckets) {
-    DCHECK(!IsAllocated());
-    size_t words = WordsForBuckets(buckets);
-    uintptr_t* ptr = reinterpret_cast<uintptr_t*>(
-        AlignedAlloc(words * kWordSize, kSystemPointerSize));
-    ptr[0] = bitmap_ >> 1;
-
-    for (size_t word_idx = 1; word_idx < words; word_idx++) {
-      ptr[word_idx] = 0;
-    }
-    bitmap_ = reinterpret_cast<Address>(ptr) + kPointerTag;
-    DCHECK(IsAllocated());
-  }
-
-  void InsertAllocated(size_t bucket_index) {
-    DCHECK(IsAllocated());
-    size_t word_idx = bucket_index / kBitsPerWord;
-    uintptr_t* word = BitmapArray() + word_idx;
-    *word |= static_cast<uintptr_t>(1) << (bucket_index % kBitsPerWord);
-  }
-
-  static size_t WordsForBuckets(size_t buckets) {
-    return (buckets / kBitsPerByte + kWordSize - 1) & ~(kWordSize - 1);
-  }
-
-  uintptr_t* BitmapArray() {
-    DCHECK(IsAllocated());
-    return reinterpret_cast<uintptr_t*>(bitmap_ & ~kPointerTag);
-  }
-
-  DISALLOW_COPY_AND_ASSIGN(PossiblyEmptyBuckets);
-};
-
-STATIC_ASSERT(std::is_standard_layout<PossiblyEmptyBuckets>::value);
-STATIC_ASSERT(sizeof(PossiblyEmptyBuckets) == kSystemPointerSize);
-
 // Data structure for maintaining a set of slots in a standard (non-large)
 // page.
 // The data structure assumes that the slots are pointer size aligned and
@@ -134,33 +35,42 @@ class SlotSet {
     KEEP_EMPTY_BUCKETS   // An empty bucket will be kept.
   };
 
+  enum class PossiblyEmpty : uint8_t {
+    kYes,       // Bucket is non-null but might be empty.
+    kNoOrNull,  // Bucket is null or cannot be empty.
+  };
+
   SlotSet() = delete;
 
   static SlotSet* Allocate(size_t buckets) {
-    //  SlotSet* slot_set --+
-    //                      |
-    //                      v
-    //    +-----------------+-------------------------+
-    //    | initial buckets |     buckets array       |
-    //    +-----------------+-------------------------+
-    //       pointer-sized    pointer-sized * buckets
+    //  SlotSet* slot_set ----------------------+
+    //                                          |
+    //                                          v
+    // +----------------------+-----------------+-------------------------+
+    // | possibly empty array | initial buckets |     buckets array       |
+    // +----------------------+-----------------+-------------------------+
+    //    1 byte * buckets       pointer-sized    pointer-sized * buckets
     //
     //
     // The SlotSet pointer points to the beginning of the buckets array for
     // faster access in the write barrier. The number of buckets is needed for
     // calculating the size of this data structure.
+    // Since pages can shrink we also store the initial_buckets size.
+    //
+    size_t possibly_empty_array_size = PossiblyEmptyArraySize(buckets);
     size_t buckets_size = buckets * sizeof(Bucket*);
-    size_t size = kInitialBucketsSize + buckets_size;
+    size_t size =
+        possibly_empty_array_size + kInitialBucketsSize + buckets_size;
     void* allocation = AlignedAlloc(size, kSystemPointerSize);
     SlotSet* slot_set = reinterpret_cast<SlotSet*>(
-        reinterpret_cast<uint8_t*>(allocation) + kInitialBucketsSize);
+        reinterpret_cast<uint8_t*>(allocation) + possibly_empty_array_size +
+        kInitialBucketsSize);
     DCHECK(
         IsAligned(reinterpret_cast<uintptr_t>(slot_set), kSystemPointerSize));
-#ifdef DEBUG
     *slot_set->initial_buckets() = buckets;
-#endif
     for (size_t i = 0; i < buckets; i++) {
       *slot_set->bucket(i) = nullptr;
+      *slot_set->possibly_empty(i) = PossiblyEmpty::kNoOrNull;
     }
     return slot_set;
   }
@@ -172,15 +82,17 @@ class SlotSet {
       slot_set->ReleaseBucket(i);
     }
 
-#ifdef DEBUG
     size_t initial_buckets = *slot_set->initial_buckets();
 
+#ifdef DEBUG
     for (size_t i = buckets; i < initial_buckets; i++) {
       DCHECK_NULL(*slot_set->bucket(i));
     }
 #endif
 
-    AlignedFree(reinterpret_cast<uint8_t*>(slot_set) - kInitialBucketsSize);
+    size_t possibly_empty_array_size = PossiblyEmptyArraySize(initial_buckets);
+    AlignedFree(reinterpret_cast<uint8_t*>(slot_set) - kInitialBucketsSize -
+                possibly_empty_array_size);
   }
 
   static size_t BucketsForSize(size_t size) {
@@ -348,12 +260,13 @@ class SlotSet {
   // Assumes that the possibly empty-array was already cleared by
   // CheckPossiblyEmptyBuckets.
   template <typename Callback>
-  size_t IterateAndTrackEmptyBuckets(
-      Address chunk_start, size_t buckets, Callback callback,
-      PossiblyEmptyBuckets* possibly_empty_buckets) {
+  size_t IterateAndTrackEmptyBuckets(Address chunk_start, size_t buckets,
+                                     Callback callback,
+                                     bool* empty_bucket_found) {
     return Iterate(chunk_start, buckets, callback,
-                   [possibly_empty_buckets, buckets](size_t bucket_index) {
-                     possibly_empty_buckets->Insert(bucket_index, buckets);
+                   [this, empty_bucket_found](size_t bucket_index) {
+                     *possibly_empty(bucket_index) = PossiblyEmpty::kYes;
+                     *empty_bucket_found = true;
                    });
   }
 
@@ -370,31 +283,42 @@ class SlotSet {
 
   // Check whether possibly empty buckets are really empty. Empty buckets are
   // freed and the possibly empty state is cleared for all buckets.
-  bool CheckPossiblyEmptyBuckets(size_t buckets,
-                                 PossiblyEmptyBuckets* possibly_empty_buckets) {
+  bool CheckPossiblyEmptyBuckets(size_t buckets) {
     bool empty = true;
     for (size_t bucket_index = 0; bucket_index < buckets; bucket_index++) {
       Bucket* bucket = LoadBucket<AccessMode::NON_ATOMIC>(bucket_index);
       if (bucket) {
-        if (possibly_empty_buckets->Contains(bucket_index)) {
+        if (*possibly_empty(bucket_index) == PossiblyEmpty::kYes) {
           if (bucket->IsEmpty()) {
             ReleaseBucket<AccessMode::NON_ATOMIC>(bucket_index);
           } else {
             empty = false;
           }
+          *possibly_empty(bucket_index) = PossiblyEmpty::kNoOrNull;
         } else {
           empty = false;
         }
       } else {
-        DCHECK(!possibly_empty_buckets->Contains(bucket_index));
+        DCHECK_EQ(*possibly_empty(bucket_index), PossiblyEmpty::kNoOrNull);
       }
     }
 
-    possibly_empty_buckets->Release();
-
     return empty;
   }
 
+  // Check wether all possibly empty entries are cleared. Only used
+  // for testing in debug-builds.
+  bool IsPossiblyEmptyCleared() {
+    size_t buckets = *initial_buckets();
+    for (size_t bucket_index = 0; bucket_index < buckets; bucket_index++) {
+      if (*possibly_empty(bucket_index) != PossiblyEmpty::kNoOrNull) {
+        return false;
+      }
+    }
+
+    return true;
+  }
+
   static const int kCellsPerBucket = 32;
   static const int kCellsPerBucketLog2 = 5;
   static const int kCellSizeBytesLog2 = 2;
@@ -576,15 +500,20 @@ class SlotSet {
     *bit_index = static_cast<int>(slot & (kBitsPerCell - 1));
   }
 
+  static size_t PossiblyEmptyArraySize(size_t buckets) {
+    return (sizeof(PossiblyEmpty) * buckets + (kSystemPointerSize - 1)) /
+           kSystemPointerSize * kSystemPointerSize;
+  }
+
   Bucket** buckets() { return reinterpret_cast<Bucket**>(this); }
   Bucket** bucket(size_t bucket_index) { return buckets() + bucket_index; }
+  PossiblyEmpty* possibly_empty(size_t bucket_index) {
+    return reinterpret_cast<PossiblyEmpty*>(buckets()) - kInitialBucketsSize -
+           1 - bucket_index;
+  }
 
-#ifdef DEBUG
   size_t* initial_buckets() { return reinterpret_cast<size_t*>(this) - 1; }
   static const int kInitialBucketsSize = sizeof(size_t);
-#else
-  static const int kInitialBucketsSize = 0;
-#endif
 };
 
 STATIC_ASSERT(std::is_standard_layout<SlotSet>::value);

src/heap/spaces.cc

@@ -750,8 +750,6 @@ MemoryChunk* MemoryChunk::Initialize(Heap* heap, Address base, size_t size,
     chunk->code_object_registry_ = nullptr;
   }
 
-  chunk->possibly_empty_buckets_.Initialize();
-
   return chunk;
 }
 
@@ -1396,7 +1394,6 @@ void MemoryChunk::ReleaseAllocatedMemoryNeededForWritableChunk() {
     code_object_registry_ = nullptr;
   }
 
-  possibly_empty_buckets_.Release();
   ReleaseSlotSet<OLD_TO_NEW>();
   ReleaseSweepingSlotSet();
   ReleaseSlotSet<OLD_TO_OLD>();

src/heap/spaces.h

@@ -24,7 +24,6 @@
 #include "src/heap/heap.h"
 #include "src/heap/invalidated-slots.h"
 #include "src/heap/marking.h"
-#include "src/heap/slot-set.h"
 #include "src/objects/free-space.h"
 #include "src/objects/heap-object.h"
 #include "src/objects/map.h"
@@ -623,8 +622,7 @@ class MemoryChunk : public BasicMemoryChunk {
       + kSystemPointerSize      // LocalArrayBufferTracker* local_tracker_
       + kIntptrSize  // std::atomic<intptr_t> young_generation_live_byte_count_
       + kSystemPointerSize   // Bitmap* young_generation_bitmap_
-      + kSystemPointerSize   // CodeObjectRegistry* code_object_registry_
-      + kSystemPointerSize;  // PossiblyEmptyBuckets possibly_empty_buckets_
+      + kSystemPointerSize;  // CodeObjectRegistry* code_object_registry_
 
   // Page size in bytes.  This must be a multiple of the OS page size.
   static const int kPageSize = 1 << kPageSizeBits;
@@ -871,10 +869,6 @@ class MemoryChunk : public BasicMemoryChunk {
 
   FreeList* free_list() { return owner()->free_list(); }
 
-  PossiblyEmptyBuckets* possibly_empty_buckets() {
-    return &possibly_empty_buckets_;
-  }
-
  protected:
   static MemoryChunk* Initialize(Heap* heap, Address base, size_t size,
                                  Address area_start, Address area_end,
@@ -970,8 +964,6 @@ class MemoryChunk : public BasicMemoryChunk {
 
   CodeObjectRegistry* code_object_registry_;
 
-  PossiblyEmptyBuckets possibly_empty_buckets_;
-
  private:
   void InitializeReservedMemory() { reservation_.Reset(); }
 

test/unittests/heap/slot-set-unittest.cc

@@ -110,20 +110,6 @@ TEST(SlotSet, Remove) {
   SlotSet::Delete(set, SlotSet::kBucketsRegularPage);
 }
 
-TEST(PossiblyEmptyBuckets, ContainsAndInsert) {
-  static const int kBuckets = 100;
-  PossiblyEmptyBuckets possibly_empty_buckets;
-  possibly_empty_buckets.Insert(0, kBuckets);
-  int last = sizeof(uintptr_t) * kBitsPerByte - 2;
-  possibly_empty_buckets.Insert(last, kBuckets);
-  EXPECT_TRUE(possibly_empty_buckets.Contains(0));
-  EXPECT_TRUE(possibly_empty_buckets.Contains(last));
-  possibly_empty_buckets.Insert(last + 1, kBuckets);
-  EXPECT_TRUE(possibly_empty_buckets.Contains(0));
-  EXPECT_TRUE(possibly_empty_buckets.Contains(last));
-  EXPECT_TRUE(possibly_empty_buckets.Contains(last + 1));
-}
-
 void CheckRemoveRangeOn(uint32_t start, uint32_t end) {
   SlotSet* set = SlotSet::Allocate(SlotSet::kBucketsRegularPage);
   uint32_t first = start == 0 ? 0 : start - kTaggedSize;

tools/v8heapconst.py

@@ -190,228 +190,228 @@ INSTANCE_TYPES = {
 
 # List of known V8 maps.
 KNOWN_MAPS = {
-  ("read_only_space", 0x00121): (161, "FreeSpaceMap"),
-  ("read_only_space", 0x00169): (162, "MetaMap"),
-  ("read_only_space", 0x001e1): (67, "NullMap"),
-  ("read_only_space", 0x00241): (156, "DescriptorArrayMap"),
-  ("read_only_space", 0x00299): (151, "WeakFixedArrayMap"),
-  ("read_only_space", 0x002e1): (160, "OnePointerFillerMap"),
-  ("read_only_space", 0x00329): (160, "TwoPointerFillerMap"),
-  ("read_only_space", 0x003a1): (67, "UninitializedMap"),
-  ("read_only_space", 0x00409): (8, "OneByteInternalizedStringMap"),
-  ("read_only_space", 0x004a1): (67, "UndefinedMap"),
-  ("read_only_space", 0x004f9): (66, "HeapNumberMap"),
-  ("read_only_space", 0x00571): (67, "TheHoleMap"),
-  ("read_only_space", 0x00611): (67, "BooleanMap"),
-  ("read_only_space", 0x006e1): (133, "ByteArrayMap"),
-  ("read_only_space", 0x00729): (118, "FixedArrayMap"),
-  ("read_only_space", 0x00771): (118, "FixedCOWArrayMap"),
-  ("read_only_space", 0x007b9): (119, "HashTableMap"),
-  ("read_only_space", 0x00801): (64, "SymbolMap"),
-  ("read_only_space", 0x00849): (40, "OneByteStringMap"),
-  ("read_only_space", 0x00891): (131, "ScopeInfoMap"),
-  ("read_only_space", 0x008d9): (166, "SharedFunctionInfoMap"),
-  ("read_only_space", 0x00921): (154, "CodeMap"),
-  ("read_only_space", 0x00969): (153, "CellMap"),
-  ("read_only_space", 0x009b1): (165, "GlobalPropertyCellMap"),
-  ("read_only_space", 0x009f9): (70, "ForeignMap"),
-  ("read_only_space", 0x00a41): (152, "TransitionArrayMap"),
-  ("read_only_space", 0x00a89): (45, "ThinOneByteStringMap"),
-  ("read_only_space", 0x00ad1): (159, "FeedbackVectorMap"),
-  ("read_only_space", 0x00b69): (67, "ArgumentsMarkerMap"),
-  ("read_only_space", 0x00c01): (67, "ExceptionMap"),
-  ("read_only_space", 0x00c99): (67, "TerminationExceptionMap"),
-  ("read_only_space", 0x00d39): (67, "OptimizedOutMap"),
-  ("read_only_space", 0x00dd1): (67, "StaleRegisterMap"),
-  ("read_only_space", 0x00e39): (132, "ScriptContextTableMap"),
-  ("read_only_space", 0x00e81): (129, "ClosureFeedbackCellArrayMap"),
-  ("read_only_space", 0x00ec9): (158, "FeedbackMetadataArrayMap"),
-  ("read_only_space", 0x00f11): (118, "ArrayListMap"),
-  ("read_only_space", 0x00f59): (65, "BigIntMap"),
-  ("read_only_space", 0x00fa1): (130, "ObjectBoilerplateDescriptionMap"),
-  ("read_only_space", 0x00fe9): (134, "BytecodeArrayMap"),
-  ("read_only_space", 0x01031): (155, "CodeDataContainerMap"),
-  ("read_only_space", 0x01079): (135, "FixedDoubleArrayMap"),
-  ("read_only_space", 0x010c1): (121, "GlobalDictionaryMap"),
-  ("read_only_space", 0x01109): (93, "ManyClosuresCellMap"),
-  ("read_only_space", 0x01151): (118, "ModuleInfoMap"),
-  ("read_only_space", 0x01199): (122, "NameDictionaryMap"),
-  ("read_only_space", 0x011e1): (93, "NoClosuresCellMap"),
-  ("read_only_space", 0x01229): (123, "NumberDictionaryMap"),
-  ("read_only_space", 0x01271): (93, "OneClosureCellMap"),
-  ("read_only_space", 0x012b9): (124, "OrderedHashMapMap"),
-  ("read_only_space", 0x01301): (125, "OrderedHashSetMap"),
-  ("read_only_space", 0x01349): (126, "OrderedNameDictionaryMap"),
-  ("read_only_space", 0x01391): (163, "PreparseDataMap"),
-  ("read_only_space", 0x013d9): (164, "PropertyArrayMap"),
-  ("read_only_space", 0x01421): (89, "SideEffectCallHandlerInfoMap"),
-  ("read_only_space", 0x01469): (89, "SideEffectFreeCallHandlerInfoMap"),
-  ("read_only_space", 0x014b1): (89, "NextCallSideEffectFreeCallHandlerInfoMap"),
-  ("read_only_space", 0x014f9): (127, "SimpleNumberDictionaryMap"),
-  ("read_only_space", 0x01541): (118, "SloppyArgumentsElementsMap"),
-  ("read_only_space", 0x01589): (146, "SmallOrderedHashMapMap"),
-  ("read_only_space", 0x015d1): (147, "SmallOrderedHashSetMap"),
-  ("read_only_space", 0x01619): (148, "SmallOrderedNameDictionaryMap"),
-  ("read_only_space", 0x01661): (68, "SourceTextModuleMap"),
-  ("read_only_space", 0x016a9): (128, "StringTableMap"),
-  ("read_only_space", 0x016f1): (69, "SyntheticModuleMap"),
-  ("read_only_space", 0x01739): (150, "UncompiledDataWithoutPreparseDataMap"),
-  ("read_only_space", 0x01781): (149, "UncompiledDataWithPreparseDataMap"),
-  ("read_only_space", 0x017c9): (167, "WeakArrayListMap"),
-  ("read_only_space", 0x01811): (120, "EphemeronHashTableMap"),
-  ("read_only_space", 0x01859): (157, "EmbedderDataArrayMap"),
-  ("read_only_space", 0x018a1): (168, "WeakCellMap"),
-  ("read_only_space", 0x018e9): (32, "StringMap"),
-  ("read_only_space", 0x01931): (41, "ConsOneByteStringMap"),
-  ("read_only_space", 0x01979): (33, "ConsStringMap"),
-  ("read_only_space", 0x019c1): (37, "ThinStringMap"),
-  ("read_only_space", 0x01a09): (35, "SlicedStringMap"),
-  ("read_only_space", 0x01a51): (43, "SlicedOneByteStringMap"),
-  ("read_only_space", 0x01a99): (34, "ExternalStringMap"),
-  ("read_only_space", 0x01ae1): (42, "ExternalOneByteStringMap"),
-  ("read_only_space", 0x01b29): (50, "UncachedExternalStringMap"),
-  ("read_only_space", 0x01b71): (0, "InternalizedStringMap"),
-  ("read_only_space", 0x01bb9): (2, "ExternalInternalizedStringMap"),
-  ("read_only_space", 0x01c01): (10, "ExternalOneByteInternalizedStringMap"),
-  ("read_only_space", 0x01c49): (18, "UncachedExternalInternalizedStringMap"),
-  ("read_only_space", 0x01c91): (26, "UncachedExternalOneByteInternalizedStringMap"),
-  ("read_only_space", 0x01cd9): (58, "UncachedExternalOneByteStringMap"),
-  ("read_only_space", 0x01d21): (67, "SelfReferenceMarkerMap"),
-  ("read_only_space", 0x01d81): (92, "EnumCacheMap"),
-  ("read_only_space", 0x01e19): (86, "ArrayBoilerplateDescriptionMap"),
-  ("read_only_space", 0x02001): (95, "InterceptorInfoMap"),
-  ("read_only_space", 0x04971): (71, "PromiseFulfillReactionJobTaskMap"),
-  ("read_only_space", 0x049b9): (72, "PromiseRejectReactionJobTaskMap"),
-  ("read_only_space", 0x04a01): (73, "CallableTaskMap"),
-  ("read_only_space", 0x04a49): (74, "CallbackTaskMap"),
-  ("read_only_space", 0x04a91): (75, "PromiseResolveThenableJobTaskMap"),
-  ("read_only_space", 0x04ad9): (78, "FunctionTemplateInfoMap"),
-  ("read_only_space", 0x04b21): (79, "ObjectTemplateInfoMap"),
-  ("read_only_space", 0x04b69): (80, "AccessCheckInfoMap"),
-  ("read_only_space", 0x04bb1): (81, "AccessorInfoMap"),
-  ("read_only_space", 0x04bf9): (82, "AccessorPairMap"),
-  ("read_only_space", 0x04c41): (83, "AliasedArgumentsEntryMap"),
-  ("read_only_space", 0x04c89): (84, "AllocationMementoMap"),
-  ("read_only_space", 0x04cd1): (87, "AsmWasmDataMap"),
-  ("read_only_space", 0x04d19): (88, "AsyncGeneratorRequestMap"),
-  ("read_only_space", 0x04d61): (90, "ClassPositionsMap"),
-  ("read_only_space", 0x04da9): (91, "DebugInfoMap"),
-  ("read_only_space", 0x04df1): (94, "FunctionTemplateRareDataMap"),
-  ("read_only_space", 0x04e39): (97, "InterpreterDataMap"),
-  ("read_only_space", 0x04e81): (98, "PromiseCapabilityMap"),
-  ("read_only_space", 0x04ec9): (99, "PromiseReactionMap"),
-  ("read_only_space", 0x04f11): (100, "PrototypeInfoMap"),
-  ("read_only_space", 0x04f59): (101, "ScriptMap"),
-  ("read_only_space", 0x04fa1): (105, "SourcePositionTableWithFrameCacheMap"),
-  ("read_only_space", 0x04fe9): (106, "SourceTextModuleInfoEntryMap"),
-  ("read_only_space", 0x05031): (107, "StackFrameInfoMap"),
-  ("read_only_space", 0x05079): (108, "StackTraceFrameMap"),
-  ("read_only_space", 0x050c1): (109, "TemplateObjectDescriptionMap"),
-  ("read_only_space", 0x05109): (110, "Tuple2Map"),
-  ("read_only_space", 0x05151): (111, "Tuple3Map"),
-  ("read_only_space", 0x05199): (112, "WasmCapiFunctionDataMap"),
-  ("read_only_space", 0x051e1): (113, "WasmDebugInfoMap"),
-  ("read_only_space", 0x05229): (114, "WasmExceptionTagMap"),
-  ("read_only_space", 0x05271): (115, "WasmExportedFunctionDataMap"),
-  ("read_only_space", 0x052b9): (116, "WasmIndirectFunctionTableMap"),
-  ("read_only_space", 0x05301): (117, "WasmJSFunctionDataMap"),
-  ("read_only_space", 0x05349): (96, "InternalClassMap"),
-  ("read_only_space", 0x05391): (103, "SmiPairMap"),
-  ("read_only_space", 0x053d9): (102, "SmiBoxMap"),
-  ("read_only_space", 0x05421): (104, "SortStateMap"),
-  ("read_only_space", 0x05469): (85, "AllocationSiteWithWeakNextMap"),
-  ("read_only_space", 0x054b1): (85, "AllocationSiteWithoutWeakNextMap"),
-  ("read_only_space", 0x054f9): (76, "LoadHandler1Map"),
-  ("read_only_space", 0x05541): (76, "LoadHandler2Map"),
-  ("read_only_space", 0x05589): (76, "LoadHandler3Map"),
-  ("read_only_space", 0x055d1): (77, "StoreHandler0Map"),
-  ("read_only_space", 0x05619): (77, "StoreHandler1Map"),
-  ("read_only_space", 0x05661): (77, "StoreHandler2Map"),
-  ("read_only_space", 0x056a9): (77, "StoreHandler3Map"),
-  ("map_space", 0x00121): (1057, "ExternalMap"),
-  ("map_space", 0x00169): (1072, "JSMessageObjectMap"),
+  ("read_only_space", 0x00119): (161, "FreeSpaceMap"),
+  ("read_only_space", 0x00161): (162, "MetaMap"),
+  ("read_only_space", 0x001d9): (67, "NullMap"),
+  ("read_only_space", 0x00239): (156, "DescriptorArrayMap"),
+  ("read_only_space", 0x00291): (151, "WeakFixedArrayMap"),
+  ("read_only_space", 0x002d9): (160, "OnePointerFillerMap"),
+  ("read_only_space", 0x00321): (160, "TwoPointerFillerMap"),
+  ("read_only_space", 0x00399): (67, "UninitializedMap"),
+  ("read_only_space", 0x00401): (8, "OneByteInternalizedStringMap"),
+  ("read_only_space", 0x00499): (67, "UndefinedMap"),
+  ("read_only_space", 0x004f1): (66, "HeapNumberMap"),
+  ("read_only_space", 0x00569): (67, "TheHoleMap"),
+  ("read_only_space", 0x00609): (67, "BooleanMap"),
+  ("read_only_space", 0x006d9): (133, "ByteArrayMap"),
+  ("read_only_space", 0x00721): (118, "FixedArrayMap"),
+  ("read_only_space", 0x00769): (118, "FixedCOWArrayMap"),
+  ("read_only_space", 0x007b1): (119, "HashTableMap"),
+  ("read_only_space", 0x007f9): (64, "SymbolMap"),
+  ("read_only_space", 0x00841): (40, "OneByteStringMap"),
+  ("read_only_space", 0x00889): (131, "ScopeInfoMap"),
+  ("read_only_space", 0x008d1): (166, "SharedFunctionInfoMap"),
+  ("read_only_space", 0x00919): (154, "CodeMap"),
+  ("read_only_space", 0x00961): (153, "CellMap"),
+  ("read_only_space", 0x009a9): (165, "GlobalPropertyCellMap"),
+  ("read_only_space", 0x009f1): (70, "ForeignMap"),
+  ("read_only_space", 0x00a39): (152, "TransitionArrayMap"),
+  ("read_only_space", 0x00a81): (45, "ThinOneByteStringMap"),
+  ("read_only_space", 0x00ac9): (159, "FeedbackVectorMap"),
+  ("read_only_space", 0x00b61): (67, "ArgumentsMarkerMap"),
+  ("read_only_space", 0x00bf9): (67, "ExceptionMap"),
+  ("read_only_space", 0x00c91): (67, "TerminationExceptionMap"),
+  ("read_only_space", 0x00d31): (67, "OptimizedOutMap"),
+  ("read_only_space", 0x00dc9): (67, "StaleRegisterMap"),
+  ("read_only_space", 0x00e31): (132, "ScriptContextTableMap"),
+  ("read_only_space", 0x00e79): (129, "ClosureFeedbackCellArrayMap"),
+  ("read_only_space", 0x00ec1): (158, "FeedbackMetadataArrayMap"),
+  ("read_only_space", 0x00f09): (118, "ArrayListMap"),
+  ("read_only_space", 0x00f51): (65, "BigIntMap"),
+  ("read_only_space", 0x00f99): (130, "ObjectBoilerplateDescriptionMap"),
+  ("read_only_space", 0x00fe1): (134, "BytecodeArrayMap"),
+  ("read_only_space", 0x01029): (155, "CodeDataContainerMap"),
+  ("read_only_space", 0x01071): (135, "FixedDoubleArrayMap"),
+  ("read_only_space", 0x010b9): (121, "GlobalDictionaryMap"),
+  ("read_only_space", 0x01101): (93, "ManyClosuresCellMap"),
+  ("read_only_space", 0x01149): (118, "ModuleInfoMap"),
+  ("read_only_space", 0x01191): (122, "NameDictionaryMap"),
+  ("read_only_space", 0x011d9): (93, "NoClosuresCellMap"),
+  ("read_only_space", 0x01221): (123, "NumberDictionaryMap"),
+  ("read_only_space", 0x01269): (93, "OneClosureCellMap"),
+  ("read_only_space", 0x012b1): (124, "OrderedHashMapMap"),
+  ("read_only_space", 0x012f9): (125, "OrderedHashSetMap"),
+  ("read_only_space", 0x01341): (126, "OrderedNameDictionaryMap"),
+  ("read_only_space", 0x01389): (163, "PreparseDataMap"),
+  ("read_only_space", 0x013d1): (164, "PropertyArrayMap"),
+  ("read_only_space", 0x01419): (89, "SideEffectCallHandlerInfoMap"),
+  ("read_only_space", 0x01461): (89, "SideEffectFreeCallHandlerInfoMap"),
+  ("read_only_space", 0x014a9): (89, "NextCallSideEffectFreeCallHandlerInfoMap"),
+  ("read_only_space", 0x014f1): (127, "SimpleNumberDictionaryMap"),
+  ("read_only_space", 0x01539): (118, "SloppyArgumentsElementsMap"),
+  ("read_only_space", 0x01581): (146, "SmallOrderedHashMapMap"),
+  ("read_only_space", 0x015c9): (147, "SmallOrderedHashSetMap"),
+  ("read_only_space", 0x01611): (148, "SmallOrderedNameDictionaryMap"),
+  ("read_only_space", 0x01659): (68, "SourceTextModuleMap"),
+  ("read_only_space", 0x016a1): (128, "StringTableMap"),
+  ("read_only_space", 0x016e9): (69, "SyntheticModuleMap"),
+  ("read_only_space", 0x01731): (150, "UncompiledDataWithoutPreparseDataMap"),
+  ("read_only_space", 0x01779): (149, "UncompiledDataWithPreparseDataMap"),
+  ("read_only_space", 0x017c1): (167, "WeakArrayListMap"),
+  ("read_only_space", 0x01809): (120, "EphemeronHashTableMap"),
+  ("read_only_space", 0x01851): (157, "EmbedderDataArrayMap"),
+  ("read_only_space", 0x01899): (168, "WeakCellMap"),
+  ("read_only_space", 0x018e1): (32, "StringMap"),
+  ("read_only_space", 0x01929): (41, "ConsOneByteStringMap"),
+  ("read_only_space", 0x01971): (33, "ConsStringMap"),
+  ("read_only_space", 0x019b9): (37, "ThinStringMap"),
+  ("read_only_space", 0x01a01): (35, "SlicedStringMap"),
+  ("read_only_space", 0x01a49): (43, "SlicedOneByteStringMap"),
+  ("read_only_space", 0x01a91): (34, "ExternalStringMap"),
+  ("read_only_space", 0x01ad9): (42, "ExternalOneByteStringMap"),
+  ("read_only_space", 0x01b21): (50, "UncachedExternalStringMap"),
+  ("read_only_space", 0x01b69): (0, "InternalizedStringMap"),
+  ("read_only_space", 0x01bb1): (2, "ExternalInternalizedStringMap"),
+  ("read_only_space", 0x01bf9): (10, "ExternalOneByteInternalizedStringMap"),
+  ("read_only_space", 0x01c41): (18, "UncachedExternalInternalizedStringMap"),
+  ("read_only_space", 0x01c89): (26, "UncachedExternalOneByteInternalizedStringMap"),
+  ("read_only_space", 0x01cd1): (58, "UncachedExternalOneByteStringMap"),
+  ("read_only_space", 0x01d19): (67, "SelfReferenceMarkerMap"),
+  ("read_only_space", 0x01d79): (92, "EnumCacheMap"),
+  ("read_only_space", 0x01e11): (86, "ArrayBoilerplateDescriptionMap"),
+  ("read_only_space", 0x01ff9): (95, "InterceptorInfoMap"),
+  ("read_only_space", 0x04969): (71, "PromiseFulfillReactionJobTaskMap"),
+  ("read_only_space", 0x049b1): (72, "PromiseRejectReactionJobTaskMap"),
+  ("read_only_space", 0x049f9): (73, "CallableTaskMap"),
+  ("read_only_space", 0x04a41): (74, "CallbackTaskMap"),
+  ("read_only_space", 0x04a89): (75, "PromiseResolveThenableJobTaskMap"),
+  ("read_only_space", 0x04ad1): (78, "FunctionTemplateInfoMap"),
+  ("read_only_space", 0x04b19): (79, "ObjectTemplateInfoMap"),
+  ("read_only_space", 0x04b61): (80, "AccessCheckInfoMap"),
+  ("read_only_space", 0x04ba9): (81, "AccessorInfoMap"),
+  ("read_only_space", 0x04bf1): (82, "AccessorPairMap"),
+  ("read_only_space", 0x04c39): (83, "AliasedArgumentsEntryMap"),
+  ("read_only_space", 0x04c81): (84, "AllocationMementoMap"),
+  ("read_only_space", 0x04cc9): (87, "AsmWasmDataMap"),
+  ("read_only_space", 0x04d11): (88, "AsyncGeneratorRequestMap"),
+  ("read_only_space", 0x04d59): (90, "ClassPositionsMap"),
+  ("read_only_space", 0x04da1): (91, "DebugInfoMap"),
+  ("read_only_space", 0x04de9): (94, "FunctionTemplateRareDataMap"),
+  ("read_only_space", 0x04e31): (97, "InterpreterDataMap"),
+  ("read_only_space", 0x04e79): (98, "PromiseCapabilityMap"),
+  ("read_only_space", 0x04ec1): (99, "PromiseReactionMap"),
+  ("read_only_space", 0x04f09): (100, "PrototypeInfoMap"),
+  ("read_only_space", 0x04f51): (101, "ScriptMap"),
+  ("read_only_space", 0x04f99): (105, "SourcePositionTableWithFrameCacheMap"),
+  ("read_only_space", 0x04fe1): (106, "SourceTextModuleInfoEntryMap"),
+  ("read_only_space", 0x05029): (107, "StackFrameInfoMap"),
+  ("read_only_space", 0x05071): (108, "StackTraceFrameMap"),
+  ("read_only_space", 0x050b9): (109, "TemplateObjectDescriptionMap"),
+  ("read_only_space", 0x05101): (110, "Tuple2Map"),
+  ("read_only_space", 0x05149): (111, "Tuple3Map"),
+  ("read_only_space", 0x05191): (112, "WasmCapiFunctionDataMap"),
+  ("read_only_space", 0x051d9): (113, "WasmDebugInfoMap"),
+  ("read_only_space", 0x05221): (114, "WasmExceptionTagMap"),
+  ("read_only_space", 0x05269): (115, "WasmExportedFunctionDataMap"),
+  ("read_only_space", 0x052b1): (116, "WasmIndirectFunctionTableMap"),
+  ("read_only_space", 0x052f9): (117, "WasmJSFunctionDataMap"),
+  ("read_only_space", 0x05341): (96, "InternalClassMap"),
+  ("read_only_space", 0x05389): (103, "SmiPairMap"),
+  ("read_only_space", 0x053d1): (102, "SmiBoxMap"),
+  ("read_only_space", 0x05419): (104, "SortStateMap"),
+  ("read_only_space", 0x05461): (85, "AllocationSiteWithWeakNextMap"),
+  ("read_only_space", 0x054a9): (85, "AllocationSiteWithoutWeakNextMap"),
+  ("read_only_space", 0x054f1): (76, "LoadHandler1Map"),
+  ("read_only_space", 0x05539): (76, "LoadHandler2Map"),
+  ("read_only_space", 0x05581): (76, "LoadHandler3Map"),
+  ("read_only_space", 0x055c9): (77, "StoreHandler0Map"),
+  ("read_only_space", 0x05611): (77, "StoreHandler1Map"),
+  ("read_only_space", 0x05659): (77, "StoreHandler2Map"),
+  ("read_only_space", 0x056a1): (77, "StoreHandler3Map"),
+  ("map_space", 0x00119): (1057, "ExternalMap"),
+  ("map_space", 0x00161): (1072, "JSMessageObjectMap"),
 }
 
 # List of known V8 objects.
 KNOWN_OBJECTS = {
-  ("read_only_space", 0x001b1): "NullValue",
-  ("read_only_space", 0x00229): "EmptyDescriptorArray",
-  ("read_only_space", 0x00289): "EmptyWeakFixedArray",
-  ("read_only_space", 0x00371): "UninitializedValue",
-  ("read_only_space", 0x00471): "UndefinedValue",
-  ("read_only_space", 0x004e9): "NanValue",
-  ("read_only_space", 0x00541): "TheHoleValue",
-  ("read_only_space", 0x005d1): "HoleNanValue",
-  ("read_only_space", 0x005e1): "TrueValue",
-  ("read_only_space", 0x00689): "FalseValue",
-  ("read_only_space", 0x006d1): "empty_string",
-  ("read_only_space", 0x00b19): "EmptyScopeInfo",
-  ("read_only_space", 0x00b29): "EmptyFixedArray",
-  ("read_only_space", 0x00b39): "ArgumentsMarker",
-  ("read_only_space", 0x00bd1): "Exception",
-  ("read_only_space", 0x00c69): "TerminationException",
-  ("read_only_space", 0x00d09): "OptimizedOut",
-  ("read_only_space", 0x00da1): "StaleRegister",
-  ("read_only_space", 0x01d69): "EmptyEnumCache",
-  ("read_only_space", 0x01dc9): "EmptyPropertyArray",
-  ("read_only_space", 0x01dd9): "EmptyByteArray",
-  ("read_only_space", 0x01de9): "EmptyObjectBoilerplateDescription",
-  ("read_only_space", 0x01e01): "EmptyArrayBoilerplateDescription",
-  ("read_only_space", 0x01e61): "EmptyClosureFeedbackCellArray",
-  ("read_only_space", 0x01e71): "EmptySloppyArgumentsElements",
-  ("read_only_space", 0x01e91): "EmptySlowElementDictionary",
-  ("read_only_space", 0x01ed9): "EmptyOrderedHashMap",
-  ("read_only_space", 0x01f01): "EmptyOrderedHashSet",
-  ("read_only_space", 0x01f29): "EmptyFeedbackMetadata",
-  ("read_only_space", 0x01f39): "EmptyPropertyCell",
-  ("read_only_space", 0x01f61): "EmptyPropertyDictionary",
-  ("read_only_space", 0x01fb1): "NoOpInterceptorInfo",
-  ("read_only_space", 0x02049): "EmptyWeakArrayList",
-  ("read_only_space", 0x02061): "InfinityValue",
-  ("read_only_space", 0x02071): "MinusZeroValue",
-  ("read_only_space", 0x02081): "MinusInfinityValue",
-  ("read_only_space", 0x02091): "SelfReferenceMarker",
-  ("read_only_space", 0x020e9): "OffHeapTrampolineRelocationInfo",
-  ("read_only_space", 0x02101): "TrampolineTrivialCodeDataContainer",
-  ("read_only_space", 0x02119): "TrampolinePromiseRejectionCodeDataContainer",
-  ("read_only_space", 0x02131): "GlobalThisBindingScopeInfo",
-  ("read_only_space", 0x02199): "EmptyFunctionScopeInfo",
-  ("read_only_space", 0x021e9): "NativeScopeInfo",
-  ("read_only_space", 0x02221): "HashSeed",
-  ("old_space", 0x00121): "ArgumentsIteratorAccessor",
-  ("old_space", 0x00191): "ArrayLengthAccessor",
-  ("old_space", 0x00201): "BoundFunctionLengthAccessor",
-  ("old_space", 0x00271): "BoundFunctionNameAccessor",
-  ("old_space", 0x002e1): "ErrorStackAccessor",
-  ("old_space", 0x00351): "FunctionArgumentsAccessor",
-  ("old_space", 0x003c1): "FunctionCallerAccessor",
-  ("old_space", 0x00431): "FunctionNameAccessor",
-  ("old_space", 0x004a1): "FunctionLengthAccessor",
-  ("old_space", 0x00511): "FunctionPrototypeAccessor",
-  ("old_space", 0x00581): "RegExpResultIndicesAccessor",
-  ("old_space", 0x005f1): "StringLengthAccessor",
-  ("old_space", 0x00661): "InvalidPrototypeValidityCell",
-  ("old_space", 0x00671): "EmptyScript",
-  ("old_space", 0x006f1): "ManyClosuresCell",
-  ("old_space", 0x00709): "ArrayConstructorProtector",
-  ("old_space", 0x00731): "NoElementsProtector",
-  ("old_space", 0x00759): "IsConcatSpreadableProtector",
-  ("old_space", 0x00781): "ArraySpeciesProtector",
-  ("old_space", 0x007a9): "TypedArraySpeciesProtector",
-  ("old_space", 0x007d1): "PromiseSpeciesProtector",
-  ("old_space", 0x007f9): "StringLengthProtector",
-  ("old_space", 0x00821): "ArrayIteratorProtector",
-  ("old_space", 0x00849): "ArrayBufferDetachingProtector",
-  ("old_space", 0x00871): "PromiseHookProtector",
-  ("old_space", 0x00899): "PromiseResolveProtector",
-  ("old_space", 0x008c1): "MapIteratorProtector",
-  ("old_space", 0x008e9): "PromiseThenProtector",
-  ("old_space", 0x00911): "SetIteratorProtector",
-  ("old_space", 0x00939): "StringIteratorProtector",
-  ("old_space", 0x00961): "SingleCharacterStringCache",
-  ("old_space", 0x01171): "StringSplitCache",
-  ("old_space", 0x01981): "RegExpMultipleCache",
-  ("old_space", 0x02191): "BuiltinsConstantsTable",
+  ("read_only_space", 0x001a9): "NullValue",
+  ("read_only_space", 0x00221): "EmptyDescriptorArray",
+  ("read_only_space", 0x00281): "EmptyWeakFixedArray",
+  ("read_only_space", 0x00369): "UninitializedValue",
+  ("read_only_space", 0x00469): "UndefinedValue",
+  ("read_only_space", 0x004e1): "NanValue",
+  ("read_only_space", 0x00539): "TheHoleValue",
+  ("read_only_space", 0x005c9): "HoleNanValue",
+  ("read_only_space", 0x005d9): "TrueValue",
+  ("read_only_space", 0x00681): "FalseValue",
+  ("read_only_space", 0x006c9): "empty_string",
+  ("read_only_space", 0x00b11): "EmptyScopeInfo",
+  ("read_only_space", 0x00b21): "EmptyFixedArray",
+  ("read_only_space", 0x00b31): "ArgumentsMarker",
+  ("read_only_space", 0x00bc9): "Exception",
+  ("read_only_space", 0x00c61): "TerminationException",
+  ("read_only_space", 0x00d01): "OptimizedOut",
+  ("read_only_space", 0x00d99): "StaleRegister",
+  ("read_only_space", 0x01d61): "EmptyEnumCache",
+  ("read_only_space", 0x01dc1): "EmptyPropertyArray",
+  ("read_only_space", 0x01dd1): "EmptyByteArray",
+  ("read_only_space", 0x01de1): "EmptyObjectBoilerplateDescription",
+  ("read_only_space", 0x01df9): "EmptyArrayBoilerplateDescription",
+  ("read_only_space", 0x01e59): "EmptyClosureFeedbackCellArray",
+  ("read_only_space", 0x01e69): "EmptySloppyArgumentsElements",
+  ("read_only_space", 0x01e89): "EmptySlowElementDictionary",
+  ("read_only_space", 0x01ed1): "EmptyOrderedHashMap",
+  ("read_only_space", 0x01ef9): "EmptyOrderedHashSet",
+  ("read_only_space", 0x01f21): "EmptyFeedbackMetadata",
+  ("read_only_space", 0x01f31): "EmptyPropertyCell",
+  ("read_only_space", 0x01f59): "EmptyPropertyDictionary",
+  ("read_only_space", 0x01fa9): "NoOpInterceptorInfo",
+  ("read_only_space", 0x02041): "EmptyWeakArrayList",
+  ("read_only_space", 0x02059): "InfinityValue",
+  ("read_only_space", 0x02069): "MinusZeroValue",
+  ("read_only_space", 0x02079): "MinusInfinityValue",
+  ("read_only_space", 0x02089): "SelfReferenceMarker",
+  ("read_only_space", 0x020e1): "OffHeapTrampolineRelocationInfo",
+  ("read_only_space", 0x020f9): "TrampolineTrivialCodeDataContainer",
+  ("read_only_space", 0x02111): "TrampolinePromiseRejectionCodeDataContainer",
+  ("read_only_space", 0x02129): "GlobalThisBindingScopeInfo",
+  ("read_only_space", 0x02191): "EmptyFunctionScopeInfo",
+  ("read_only_space", 0x021e1): "NativeScopeInfo",
+  ("read_only_space", 0x02219): "HashSeed",
+  ("old_space", 0x00119): "ArgumentsIteratorAccessor",
+  ("old_space", 0x00189): "ArrayLengthAccessor",
+  ("old_space", 0x001f9): "BoundFunctionLengthAccessor",
+  ("old_space", 0x00269): "BoundFunctionNameAccessor",
+  ("old_space", 0x002d9): "ErrorStackAccessor",
+  ("old_space", 0x00349): "FunctionArgumentsAccessor",
+  ("old_space", 0x003b9): "FunctionCallerAccessor",
+  ("old_space", 0x00429): "FunctionNameAccessor",
+  ("old_space", 0x00499): "FunctionLengthAccessor",
+  ("old_space", 0x00509): "FunctionPrototypeAccessor",
+  ("old_space", 0x00579): "RegExpResultIndicesAccessor",
+  ("old_space", 0x005e9): "StringLengthAccessor",
+  ("old_space", 0x00659): "InvalidPrototypeValidityCell",
+  ("old_space", 0x00669): "EmptyScript",
+  ("old_space", 0x006e9): "ManyClosuresCell",
+  ("old_space", 0x00701): "ArrayConstructorProtector",
+  ("old_space", 0x00729): "NoElementsProtector",
+  ("old_space", 0x00751): "IsConcatSpreadableProtector",
+  ("old_space", 0x00779): "ArraySpeciesProtector",
+  ("old_space", 0x007a1): "TypedArraySpeciesProtector",
+  ("old_space", 0x007c9): "PromiseSpeciesProtector",
+  ("old_space", 0x007f1): "StringLengthProtector",
+  ("old_space", 0x00819): "ArrayIteratorProtector",
+  ("old_space", 0x00841): "ArrayBufferDetachingProtector",
+  ("old_space", 0x00869): "PromiseHookProtector",
+  ("old_space", 0x00891): "PromiseResolveProtector",
+  ("old_space", 0x008b9): "MapIteratorProtector",
+  ("old_space", 0x008e1): "PromiseThenProtector",
+  ("old_space", 0x00909): "SetIteratorProtector",
+  ("old_space", 0x00931): "StringIteratorProtector",
+  ("old_space", 0x00959): "SingleCharacterStringCache",
+  ("old_space", 0x01169): "StringSplitCache",
+  ("old_space", 0x01979): "RegExpMultipleCache",
+  ("old_space", 0x02189): "BuiltinsConstantsTable",
 }
 
 # List of known V8 Frame Markers.