Merged bleeding_edge r599:645 into regexp2000.

src/objects.h

Index: src/objects.h
===================================================================
--- src/objects.h	(revision 645)
+++ src/objects.h	(working copy)
@@ -395,29 +395,30 @@
 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 4 indicates that the string is a symbol (if set) or
+// If bit 7 is clear, bit 5 indicates that the string is a symbol (if set) or
 // not (if cleared).
-const uint32_t kIsSymbolMask = 0x10;
+const uint32_t kIsSymbolMask = 0x20;
 const uint32_t kNotSymbolTag = 0x0;
-const uint32_t kSymbolTag = 0x10;
+const uint32_t kSymbolTag = 0x20;
 
-// 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, 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 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,
@@ -625,6 +626,7 @@
   inline bool IsOddball();
   inline bool IsSharedFunctionInfo();
   inline bool IsJSValue();
+  inline bool IsStringWrapper();
   inline bool IsProxy();
   inline bool IsBoolean();
   inline bool IsJSArray();
@@ -1041,7 +1043,11 @@
   // 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);
@@ -1973,9 +1979,6 @@
   // 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);
@@ -2421,6 +2424,17 @@
   // 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
@@ -2805,7 +2819,7 @@
   // [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
@@ -3154,8 +3168,8 @@
   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;
 
@@ -3176,14 +3190,14 @@
 
   // 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;