Fix string and descriptor array decoding in grokdump.

tools/grokdump.py

 #!/usr/bin/env python
 #
 # 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
@@ skipping 1011 matching lines @@
       p.Print("TransitionsOrBackPointer: %s" % (transitions))
 
   def __init__(self, heap, map, address):
     HeapObject.__init__(self, heap, map, address)
     self.instance_type = \
         heap.reader.ReadU8(self.address + self.InstanceTypeOffset())
 
 
 class String(HeapObject):
   def LengthOffset(self):
-    return self.heap.PointerSize()
+    # First word after the map is the hash, the second is the length.
+    return self.heap.PointerSize() * 2
 
   def __init__(self, heap, map, address):
     HeapObject.__init__(self, heap, map, address)
     self.length = self.SmiField(self.LengthOffset())
 
   def GetChars(self):
     return "?string?"
 
   def Print(self, p):
     p.Print(str(self))
@@ skipping 165 matching lines @@
     attributes = self.Decode(3, 3, value)
     result = []
     if (attributes & 0): result += ["ReadOnly"]
     if (attributes & 1): result += ["DontEnum"]
     if (attributes & 2): result += ["DontDelete"]
     return "[" + (",".join(result)) + "]"
 
   def Deleted(self, value):
     return self.Decode(6, 1, value) == 1
 
-  def Storage(self, value):
-    return self.Decode(7, 11, value)
+  def FieldIndex(self, value):
+    return self.Decode(20, 11, value)
 
   def Pointer(self, value):
-    return self.Decode(18, 11, value)
+    return self.Decode(6, 11, value)
 
   def Details(self, di, value):
     return (
         di,
         self.Type(value),
         self.Attributes(value),
-        self.Storage(value),
+        self.FieldIndex(value),
         self.Pointer(value)
     )
 
 
   def Print(self, p):
     length = self.Length()
     array = self.array
 
     p.Print("Descriptors(%08x, length=%d)" % (array.address, length))
     p.Print("[et] %s" % (array.Get(1)))
 
     for di in xrange(length):
       i = 2 + di * 3
       p.Print("0x%x" % (array.address + array.MemberOffset(i)))
       p.Print("[%i] name:    %s" % (di, array.Get(i + 0)))
-      p.Print("[%i] details: %s %s enum %i pointer %i" % \
+      p.Print("[%i] details: %s %s field-index %i pointer %i" % \
               self.Details(di, array.Get(i + 1)))
       p.Print("[%i] value:   %s" % (di, array.Get(i + 2)))
 
     end = self.array.length // 3
     if length != end:
       p.Print("[%i-%i] slack descriptors" % (length, end))
 
 
 class TransitionArray(object):
   def __init__(self, array):
@@ skipping 738 matching lines @@
   options, args = parser.parse_args()
   if os.path.exists(options.objdump):
     disasm.OBJDUMP_BIN = options.objdump
     OBJDUMP_BIN = options.objdump
   else:
     print "Cannot find %s, falling back to default objdump" % options.objdump
   if len(args) != 1:
     parser.print_help()
     sys.exit(1)
   AnalyzeMinidump(options, args[0])