Revert of Replace slots buffer with remembered set.

src/heap/slot-set.h

Index: src/heap/slot-set.h
diff --git a/src/heap/slot-set.h b/src/heap/slot-set.h
index e55ffe98e60aa88f74c2e886f226f37eb21bab93..6144706f71e3ed34d81693557b4fe87492499619 100644
--- a/src/heap/slot-set.h
+++ b/src/heap/slot-set.h
@@ -7,12 +7,9 @@
 
 #include "src/allocation.h"
 #include "src/base/bits.h"
-#include "src/utils.h"
 
 namespace v8 {
 namespace internal {
-
-enum SlotCallbackResult { KEEP_SLOT, REMOVE_SLOT };
 
 // Data structure for maintaining a set of slots in a standard (non-large)
 // page. The base address of the page must be set with SetPageStart before any
@@ -22,6 +19,8 @@
 // Each bucket is a bitmap with a bit corresponding to a single slot offset.
 class SlotSet : public Malloced {
  public:
+  enum CallbackResult { KEEP_SLOT, REMOVE_SLOT };
+
   SlotSet() {
     for (int i = 0; i < kBuckets; i++) {
       bucket[i] = nullptr;
@@ -214,124 +213,6 @@
   Address page_start_;
 };
 
-enum SlotType {
-  EMBEDDED_OBJECT_SLOT,
-  OBJECT_SLOT,
-  RELOCATED_CODE_OBJECT,
-  CELL_TARGET_SLOT,
-  CODE_TARGET_SLOT,
-  CODE_ENTRY_SLOT,
-  DEBUG_TARGET_SLOT,
-  NUMBER_OF_SLOT_TYPES
-};
-
-// Data structure for maintaining a multiset of typed slots in a page.
-// Typed slots can only appear in Code and JSFunction objects, so
-// the maximum possible offset is limited by the LargePage::kMaxCodePageSize.
-// The implementation is a chain of chunks, where each chunks is an array of
-// encoded (slot type, slot offset) pairs.
-// There is no duplicate detection and we do not expect many duplicates because
-// typed slots contain V8 internal pointers that are not directly exposed to JS.
-class TypedSlotSet {
- public:
-  typedef uint32_t TypedSlot;
-  static const int kMaxOffset = 1 << 29;
-
-  explicit TypedSlotSet(Address page_start) : page_start_(page_start) {
-    chunk_ = new Chunk(nullptr, kInitialBufferSize);
-  }
-
-  ~TypedSlotSet() {
-    Chunk* chunk = chunk_;
-    while (chunk != nullptr) {
-      Chunk* next = chunk->next;
-      delete chunk;
-      chunk = next;
-    }
-  }
-
-  // The slot offset specifies a slot at address page_start_ + offset.
-  void Insert(SlotType type, int offset) {
-    TypedSlot slot = ToTypedSlot(type, offset);
-    if (!chunk_->AddSlot(slot)) {
-      chunk_ = new Chunk(chunk_, NextCapacity(chunk_->capacity));
-      bool added = chunk_->AddSlot(slot);
-      DCHECK(added);
-      USE(added);
-    }
-  }
-
-  // Iterate over all slots in the set and for each slot invoke the callback.
-  // If the callback returns REMOVE_SLOT then the slot is removed from the set.
-  // Returns the new number of slots.
-  //
-  // Sample usage:
-  // Iterate([](SlotType slot_type, Address slot_address) {
-  //    if (good(slot_type, slot_address)) return KEEP_SLOT;
-  //    else return REMOVE_SLOT;
-  // });
-  template <typename Callback>
-  int Iterate(Callback callback) {
-    STATIC_ASSERT(NUMBER_OF_SLOT_TYPES < 8);
-    const TypedSlot kRemovedSlot = TypeField::encode(NUMBER_OF_SLOT_TYPES);
-    Chunk* chunk = chunk_;
-    int new_count = 0;
-    while (chunk != nullptr) {
-      TypedSlot* buffer = chunk->buffer;
-      int count = chunk->count;
-      for (int i = 0; i < count; i++) {
-        TypedSlot slot = buffer[i];
-        if (slot != kRemovedSlot) {
-          SlotType type = TypeField::decode(slot);
-          Address addr = page_start_ + OffsetField::decode(slot);
-          if (callback(type, addr) == KEEP_SLOT) {
-            new_count++;
-          } else {
-            buffer[i] = kRemovedSlot;
-          }
-        }
-      }
-      chunk = chunk->next;
-    }
-    return new_count;
-  }
-
- private:
-  static const int kInitialBufferSize = 100;
-  static const int kMaxBufferSize = 16 * KB;
-
-  static int NextCapacity(int capacity) {
-    return Min(kMaxBufferSize, capacity * 2);
-  }
-
-  static TypedSlot ToTypedSlot(SlotType type, int offset) {
-    return TypeField::encode(type) | OffsetField::encode(offset);
-  }
-
-  class OffsetField : public BitField<int, 0, 29> {};
-  class TypeField : public BitField<SlotType, 29, 3> {};
-
-  struct Chunk : Malloced {
-    explicit Chunk(Chunk* next_chunk, int capacity)
-        : next(next_chunk), count(0), capacity(capacity) {
-      buffer = NewArray<TypedSlot>(capacity);
-    }
-    bool AddSlot(TypedSlot slot) {
-      if (count == capacity) return false;
-      buffer[count++] = slot;
-      return true;
-    }
-    ~Chunk() { DeleteArray(buffer); }
-    Chunk* next;
-    int count;
-    int capacity;
-    TypedSlot* buffer;
-  };
-
-  Address page_start_;
-  Chunk* chunk_;
-};
-
 }  // namespace internal
 }  // namespace v8