Separate Cell and PropertyCell spaces

src/objects.h

 // 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 330 matching lines @@
   V(EXTERNAL_ASCII_INTERNALIZED_STRING_TYPE)                                   \
   V(EXTERNAL_INTERNALIZED_STRING_WITH_ONE_BYTE_DATA_TYPE)                      \
   V(SHORT_EXTERNAL_INTERNALIZED_STRING_TYPE)                                   \
   V(SHORT_EXTERNAL_ASCII_INTERNALIZED_STRING_TYPE)                             \
   V(SHORT_EXTERNAL_INTERNALIZED_STRING_WITH_ONE_BYTE_DATA_TYPE)                \
                                                                                \
   V(SYMBOL_TYPE)                                                               \
   V(MAP_TYPE)                                                                  \
   V(CODE_TYPE)                                                                 \
   V(ODDBALL_TYPE)                                                              \
+  V(CELL_TYPE)                                                                 \

[Michael Starzinger, 2013/06/12 13:23:25]

Can we add the "Cell" type to the type hierarchy ASCII-art at the top if this
file?

[danno, 2013/06/12 14:24:28]

Done.

   V(JS_GLOBAL_PROPERTY_CELL_TYPE)                                              \
   V(BOX_TYPE)                                                                  \
                                                                                \
   V(HEAP_NUMBER_TYPE)                                                          \
   V(FOREIGN_TYPE)                                                              \
   V(BYTE_ARRAY_TYPE)                                                           \
   V(FREE_SPACE_TYPE)                                                           \
   /* Note: the order of these external array */                                \
   /* types is relied upon in */                                                \
   /* Object::IsExternalArray(). */                                             \
@@ skipping 301 matching lines @@
   SHORT_EXTERNAL_INTERNALIZED_STRING_WITH_ONE_BYTE_DATA_TYPE =
       SHORT_EXTERNAL_STRING_WITH_ONE_BYTE_DATA_TYPE | kInternalizedTag,
 
   // Non-string names
   SYMBOL_TYPE = kNotStringTag,  // LAST_NAME_TYPE, FIRST_NONSTRING_TYPE
 
   // Objects allocated in their own spaces (never in new space).
   MAP_TYPE,
   CODE_TYPE,
   ODDBALL_TYPE,
+  CELL_TYPE,
   JS_GLOBAL_PROPERTY_CELL_TYPE,
   BOX_TYPE,
 
   // "Data", objects that cannot contain non-map-word pointers to heap
   // objects.
   HEAP_NUMBER_TYPE,
   FOREIGN_TYPE,
   BYTE_ARRAY_TYPE,
   FREE_SPACE_TYPE,
   EXTERNAL_BYTE_ARRAY_TYPE,  // FIRST_EXTERNAL_ARRAY_TYPE
@@ skipping 152 matching lines @@
                          WriteBarrierMode mode = UPDATE_WRITE_BARRIER); \
 
 
 class AccessorPair;
 class DictionaryElementsAccessor;
 class ElementsAccessor;
 class Failure;
 class FixedArrayBase;
 class ObjectVisitor;
 class StringStream;
+class Type;
 
 struct ValueInfo : public Malloced {
   ValueInfo() : type(FIRST_TYPE), ptr(NULL), str(NULL), number(0) { }
   InstanceType type;
   Object* ptr;
   const char* str;
   double number;
 };
 
 
@@ skipping 150 matching lines @@
   V(CodeCacheHashTable)                        \
   V(PolymorphicCodeCacheHashTable)             \
   V(MapCache)                                  \
   V(Primitive)                                 \
   V(GlobalObject)                              \
   V(JSGlobalObject)                            \
   V(JSBuiltinsObject)                          \
   V(JSGlobalProxy)                             \
   V(UndetectableObject)                        \
   V(AccessCheckNeeded)                         \
+  V(Cell)                                      \
   V(JSGlobalPropertyCell)                      \
   V(ObjectHashTable)                           \
 
 
 // Object is the abstract superclass for all classes in the
 // object hierarchy.
 // Object does not use any virtual functions to avoid the
 // allocation of the C++ vtable.
 // Since Smi and Failure are subclasses of Object no
 // data members can be present in Object.
@@ skipping 3347 matching lines @@
   // Casting.
   static inline DeoptimizationOutputData* cast(Object* obj);
 
 #if defined(OBJECT_PRINT) || defined(ENABLE_DISASSEMBLER)
   void DeoptimizationOutputDataPrint(FILE* out);
 #endif
 };
 
 
 // Forward declaration.
+class Cell;
 class JSGlobalPropertyCell;
 
 // TypeFeedbackCells is a fixed array used to hold the association between
 // cache cells and AST ids for code generated by the full compiler.
 // The format of the these objects is
 //   [i * 2]: Global property cell of ith cache cell.
 //   [i * 2 + 1]: Ast ID for ith cache cell.
 class TypeFeedbackCells: public FixedArray {
  public:
   int CellCount() { return length() / 2; }
   static int LengthOfFixedArray(int cell_count) { return cell_count * 2; }
 
   // Accessors for AST ids associated with cache values.
   inline TypeFeedbackId AstId(int index);
   inline void SetAstId(int index, TypeFeedbackId id);
 
   // Accessors for global property cells holding the cache values.
-  inline JSGlobalPropertyCell* Cell(int index);
-  inline void SetCell(int index, JSGlobalPropertyCell* cell);
+  inline Cell* GetCell(int index);
+  inline void SetCell(int index, Cell* cell);
 
   // The object that indicates an uninitialized cache.
   static inline Handle<Object> UninitializedSentinel(Isolate* isolate);
 
   // The object that indicates a megamorphic state.
   static inline Handle<Object> MegamorphicSentinel(Isolate* isolate);
 
   // The object that indicates a monomorphic state of Array with
   // ElementsKind
   static inline Handle<Object> MonomorphicArraySentinel(Isolate* isolate,
@@ skipping 986 matching lines @@
 
   int NumberOfOwnDescriptors() {
     return NumberOfOwnDescriptorsBits::decode(bit_field3());
   }
 
   void SetNumberOfOwnDescriptors(int number) {
     ASSERT(number <= instance_descriptors()->number_of_descriptors());
     set_bit_field3(NumberOfOwnDescriptorsBits::update(bit_field3(), number));
   }
 
-  inline JSGlobalPropertyCell* RetrieveDescriptorsPointer();
+  inline Cell* RetrieveDescriptorsPointer();
 
   int EnumLength() {
     return EnumLengthBits::decode(bit_field3());
   }
 
   void SetEnumLength(int length) {
     if (length != kInvalidEnumCache) {
       ASSERT(length >= 0);
       ASSERT(length == 0 || instance_descriptors()->HasEnumCache());
       ASSERT(length <= NumberOfOwnDescriptors());
@@ skipping 3133 matching lines @@
 
   STATIC_CHECK(kKindOffset == Internals::kOddballKindOffset);
   STATIC_CHECK(kNull == Internals::kNullOddballKind);
   STATIC_CHECK(kUndefined == Internals::kUndefinedOddballKind);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(Oddball);
 };
 
 
-class JSGlobalPropertyCell: public HeapObject {
+class Cell: public HeapObject {
  public:
-  // [value]: value of the global property.

[Michael Starzinger, 2013/06/12 13:23:25]

I actually like the comment lines and sometimes grep for "[foo]" in the file,
can I get the comment line back? Or I could just learn to grep for
"DECL_ACCESSORS" but unfortunately we don't have that macro for int accessors.

[danno, 2013/06/12 14:24:28]

Done.

   DECL_ACCESSORS(value, Object)
 
   // Casting.
-  static inline JSGlobalPropertyCell* cast(Object* obj);
+  static inline Cell* cast(Object* obj);
 
-  static inline JSGlobalPropertyCell* FromValueAddress(Address value) {
-    return cast(FromAddress(value - kValueOffset));
+  static inline Cell* FromValueAddress(Address value) {
+    Object* result = FromAddress(value - kValueOffset);
+    ASSERT(result->IsCell() || result->IsJSGlobalPropertyCell());
+    return static_cast<Cell*>(result);
   }
 
   inline Address ValueAddress() {
     return address() + kValueOffset;
   }
 
   // Dispatched behavior.
-  DECLARE_PRINTER(JSGlobalPropertyCell)
-  DECLARE_VERIFIER(JSGlobalPropertyCell)
+  DECLARE_PRINTER(Cell)
+  DECLARE_VERIFIER(Cell)
 
   // Layout description.
   static const int kValueOffset = HeapObject::kHeaderSize;
   static const int kSize = kValueOffset + kPointerSize;
 
   typedef FixedBodyDescriptor<kValueOffset,
                               kValueOffset + kPointerSize,
                               kSize> BodyDescriptor;
 
  private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(Cell);
+};
+
+
+class JSGlobalPropertyCell: public Cell {
+ public:
+  Type* type();
+  void set_type(Type* value, WriteBarrierMode mode = UPDATE_WRITE_BARRIER);

[Michael Starzinger, 2013/06/12 13:23:25]

Can we use the DECL_ACCESSORS macro to declare this pair here?

[danno, 2013/06/12 14:24:28]

No, unfortunately not. Note that they are not inlined. The problem is that we
would have type include type.h in objects-inl.h, and that's not possible due to
circular dependencies.

+
+  // Casting.
+  static inline JSGlobalPropertyCell* cast(Object* obj);
+
+  inline Address TypeAddress() {
+    return address() + kTypeOffset;
+  }
+
+  // Dispatched behavior.
+  DECLARE_PRINTER(JSGlobalPropertyCell)
+  DECLARE_VERIFIER(JSGlobalPropertyCell)
+
+  // Layout description.
+  static const int kTypeOffset = kValueOffset + kPointerSize;
+  static const int kSize = kTypeOffset + kPointerSize;
+
+  typedef FixedBodyDescriptor<
+      kValueOffset,

[Michael Starzinger, 2013/06/12 13:23:25]

nit: Should fit into three lines if we remove the first line-break.

[danno, 2013/06/12 14:24:28]

Done.

+      kTypeOffset + kPointerSize,
+      JSGlobalPropertyCell::kSize> BodyDescriptor;
+
+ private:
+  DECL_ACCESSORS(type_raw, Object)
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSGlobalPropertyCell);
 };
 
 
 // The JSProxy describes EcmaScript Harmony proxies
 class JSProxy: public JSReceiver {
  public:
   // [handler]: The handler property.
   DECL_ACCESSORS(handler, Object)
 
@@ skipping 1082 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_