Merged bleeding_edge r599:645 into regexp2000.

src/objects.h

 // Copyright 2006-2008 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 377 matching lines @@
   V(SCRIPT, Script, script)
 
 
 // We use the full 8 bits of the instance_type field to encode heap object
 // instance types.  The high-order bit (bit 7) is set if the object is not a
 // string, and cleared if it is a string.
 const uint32_t kIsNotStringMask = 0x80;
 const uint32_t kStringTag = 0x0;
 const uint32_t kNotStringTag = 0x80;
 
-// If bit 7 is clear, bits 5 and 6 are the string's size (short, medium, or
-// long).
-const uint32_t kStringSizeMask = 0x60;
-const uint32_t kShortStringTag = 0x0;
-const uint32_t kMediumStringTag = 0x20;
-const uint32_t kLongStringTag = 0x40;
+// If bit 7 is clear, bit 5 indicates that the string is a symbol (if set) or
+// not (if cleared).
+const uint32_t kIsSymbolMask = 0x20;
+const uint32_t kNotSymbolTag = 0x0;
+const uint32_t kSymbolTag = 0x20;
 
-// If bit 7 is clear, bit 4 indicates that the string is a symbol (if set) or
-// not (if cleared).
-const uint32_t kIsSymbolMask = 0x10;
-const uint32_t kNotSymbolTag = 0x0;
-const uint32_t kSymbolTag = 0x10;
+// If bit 7 is clear, bits 3 and 4 are the string's size (short, medium or
+// long).  These values are very special in that they are also used to shift
+// the length field to get the length, removing the hash value.  This avoids
+// using if or switch when getting the length of a string.
+const uint32_t kStringSizeMask = 0x18;
+const uint32_t kShortStringTag = 0x18;
+const uint32_t kMediumStringTag = 0x10;
+const uint32_t kLongStringTag = 0x00;
 
-// If bit 7 is clear, and the string representation is a sequential string,
-// then bit 3 indicates whether the string consists of two-byte characters or
-// one-byte characters.
-const uint32_t kStringEncodingMask = 0x8;
+// If bit 7 is clear then bit 2 indicates whether the string consists of
+// two-byte characters or one-byte characters.
+const uint32_t kStringEncodingMask = 0x4;
 const uint32_t kTwoByteStringTag = 0x0;
-const uint32_t kAsciiStringTag = 0x8;
+const uint32_t kAsciiStringTag = 0x4;
 
-// If bit 7 is clear, the low-order 3 bits indicate the representation
+// If bit 7 is clear, the low-order 2 bits indicate the representation
 // of the string.
-const uint32_t kStringRepresentationMask = 0x07;
+const uint32_t kStringRepresentationMask = 0x03;
 enum StringRepresentationTag {
   kSeqStringTag = 0x0,
   kConsStringTag = 0x1,
   kSlicedStringTag = 0x2,
   kExternalStringTag = 0x3
 };
 
 enum InstanceType {
   SHORT_SYMBOL_TYPE = kShortStringTag | kSymbolTag | kSeqStringTag,
   MEDIUM_SYMBOL_TYPE = kMediumStringTag | kSymbolTag | kSeqStringTag,
@@ skipping 187 matching lines @@
   inline bool IsMap();
   inline bool IsFixedArray();
   inline bool IsDescriptorArray();
   inline bool IsContext();
   inline bool IsGlobalContext();
   inline bool IsJSFunction();
   inline bool IsCode();
   inline bool IsOddball();
   inline bool IsSharedFunctionInfo();
   inline bool IsJSValue();
+  inline bool IsStringWrapper();
   inline bool IsProxy();
   inline bool IsBoolean();
   inline bool IsJSArray();
   inline bool IsJSRegExp();
   inline bool IsHashTable();
   inline bool IsDictionary();
   inline bool IsSymbolTable();
   inline bool IsCompilationCacheTable();
   inline bool IsMapCache();
   inline bool IsLookupCache();
@@ skipping 396 matching lines @@
   inline bool IsOverflowed();
 
   // Mutate this object's map pointer to indicate that the object is
   // overflowed.
   inline void SetOverflow();
 
   // Mutate this object's map pointer to remove the indication that the
   // object is overflowed (ie, partially restore the map pointer).
   inline void ClearOverflow();
 
-  static inline Object* GetHeapObjectField(HeapObject* obj, int index);
+  // Returns the field at offset in obj, as a read/write Object* reference.
+  // Does no checking, and is safe to use during GC, while maps are invalid.
+  // Does not update remembered sets, so should only be assigned to
+  // during marking GC.
+  static inline Object** RawField(HeapObject* obj, int offset);
 
   // Casting.
   static inline HeapObject* cast(Object* obj);
 
   // Return the write barrier mode for this.
   inline WriteBarrierMode GetWriteBarrierMode();
 
   // Dispatched behavior.
   void HeapObjectShortPrint(StringStream* accumulator);
 #ifdef DEBUG
@@ skipping 911 matching lines @@
   // Returns the number of enumerable elements in the dictionary.
   int NumberOfEnumElements();
 
   // Copies keys to preallocated fixed array.
   void CopyKeysTo(FixedArray* storage, PropertyAttributes filter);
   // Copies enumerable keys to preallocated fixed array.
   void CopyEnumKeysTo(FixedArray* storage, FixedArray* sort_array);
   // Fill in details for properties into storage.
   void CopyKeysTo(FixedArray* storage);
 
-  // Returns the value at entry.
-  static int ValueIndexFor(int entry) { return EntryToIndex(entry)+1; }
-
   // For transforming properties of a JSObject.
   Object* TransformPropertiesToFastFor(JSObject* obj,
                                        int unused_property_fields);
 
   // If slow elements are required we will never go back to fast-case
   // for the elements kept in this dictionary.  We require slow
   // elements if an element has been added at an index larger than
   // kRequiresSlowElementsLimit.
   inline bool requires_slow_elements();
 
@@ skipping 425 matching lines @@
   // Returns the found code or undefined if absent.
   Object* FindInCodeCache(String* name, Code::Flags flags);
 
   // Returns the non-negative index of the code object if it is in the
   // cache and -1 otherwise.
   int IndexInCodeCache(Code* code);
 
   // Removes a code object from the code cache at the given index.
   void RemoveFromCodeCache(int index);
 
+  // For every transition in this map, makes the transition's
+  // target's prototype pointer point back to this map.
+  // This is undone in MarkCompactCollector::ClearNonLiveTransitions().
+  void CreateBackPointers();
+
+  // Set all map transitions from this map to dead maps to null.
+  // Also, restore the original prototype on the targets of these
+  // transitions, so that we do not process this map again while
+  // following back pointers.
+  void ClearNonLiveTransitions(Object* real_prototype);
+
   // Dispatched behavior.
   void MapIterateBody(ObjectVisitor* v);
 #ifdef DEBUG
   void MapPrint();
   void MapVerify();
 #endif
 
   // Layout description.
   static const int kInstanceSizesOffset = HeapObject::kHeaderSize;
   static const int kInstanceAttributesOffset = kInstanceSizesOffset + kIntSize;
@@ skipping 364 matching lines @@
 // Forward declaration.
 class JSBuiltinsObject;
 
 // Common super class for JavaScript global objects and the special
 // builtins global objects.
 class GlobalObject: public JSObject {
  public:
   // [builtins]: the object holding the runtime routines written in JS.
   DECL_ACCESSORS(builtins, JSBuiltinsObject)
 
-  // [global context]: the global context corresponding to this global objet.
+  // [global context]: the global context corresponding to this global object.
   DECL_ACCESSORS(global_context, Context)
 
   // [global receiver]: the global receiver object of the context
   DECL_ACCESSORS(global_receiver, JSObject)
 
   // Casting.
   static inline GlobalObject* cast(Object* obj);
 
   // Layout description.
   static const int kBuiltinsOffset = JSObject::kHeaderSize;
@@ skipping 328 matching lines @@
   void StringPrint();
   void StringVerify();
 #endif
   inline bool IsFlat();
 
   // Layout description.
   static const int kLengthOffset = HeapObject::kHeaderSize;
   static const int kSize = kLengthOffset + kIntSize;
 
   // Limits on sizes of different types of strings.
-  static const int kMaxShortStringSize = 255;
-  static const int kMaxMediumStringSize = 65535;
+  static const int kMaxShortStringSize = 63;
+  static const int kMaxMediumStringSize = 16383;
 
   static const int kMaxArrayIndexSize = 10;
 
   // Max ascii char code.
   static const int kMaxAsciiCharCode = unibrow::Utf8::kMaxOneByteChar;
 
   // Minimum length for a cons or sliced string.
   static const int kMinNonFlatLength = 13;
 
   // Mask constant for checking if a string has a computed hash code
   // and if it is an array index.  The least significant bit indicates
   // whether a hash code has been computed.  If the hash code has been
   // computed the 2nd bit tells whether the string can be used as an
   // array index.
   static const int kHashComputedMask = 1;
   static const int kIsArrayIndexMask = 1 << 1;
   static const int kNofLengthBitFields = 2;
 
   // Array index strings this short can keep their index in the hash
   // field.
-  static const int kMaxCachedArrayIndexLength = 6;
+  static const int kMaxCachedArrayIndexLength = 7;
 
   // Shift constants for retriving length and hash code from
   // length/hash field.
   static const int kHashShift = kNofLengthBitFields;
-  static const int kShortLengthShift = 3 * kBitsPerByte;
-  static const int kMediumLengthShift = 2 * kBitsPerByte;
-  static const int kLongLengthShift = kHashShift;
+  static const int kShortLengthShift = kHashShift + kShortStringTag;
+  static const int kMediumLengthShift = kHashShift + kMediumStringTag;
+  static const int kLongLengthShift = kHashShift + kLongStringTag;
 
   // Limit for truncation in short printing.
   static const int kMaxShortPrintLength = 1024;
 
   // Support for regular expressions.
   const uc16* GetTwoByteData();
   const uc16* GetTwoByteData(unsigned start);
 
   // Support for StringInputBuffer
   static const unibrow::byte* ReadBlock(String* input,
@@ skipping 922 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_