Class Map

deps/v8/tools/grokdump.py:1247–1358

class Map(HeapObject):
  def Decode(self, offset, size, value):
    return (value >> offset) & ((1 << size) - 1)

  # Instance Sizes
  def InstanceSizesOffset(self):
    return self.heap.TaggedPointerSize()

  def InstanceSizeOffset(self):
    return self.InstanceSizesOffset()

  def InObjectProperties(self):
    return self.InstanceSizeOffset() + 1

  def UnusedByte(self):
    return self.InObjectProperties() + 1

  def VisitorId(self):
    return self.UnusedByte() + 1

  # Instance Attributes
  def InstanceAttributesOffset(self):
    return self.InstanceSizesOffset() + self.heap.IntSize()

  def InstanceTypeOffset(self):
    return self.InstanceAttributesOffset()

  def BitFieldOffset(self):
    return self.InstanceTypeOffset() + 1

  def BitField2Offset(self):
    return self.BitFieldOffset() + 1

  def UnusedPropertyFieldsOffset(self):
    return self.BitField2Offset() + 1

  # Other fields
  def BitField3Offset(self):
    return self.InstanceAttributesOffset() + self.heap.IntSize()

  def PrototypeOffset(self):
    return self.BitField3Offset() + self.heap.TaggedPointerSize()

  def ConstructorOrBackPointerOffset(self):
    return self.PrototypeOffset() + self.heap.TaggedPointerSize()

  def TransitionsOrPrototypeInfoOffset(self):
    return self.ConstructorOrBackPointerOffset() + self.heap.TaggedPointerSize()

  def DescriptorsOffset(self):
    return (self.TransitionsOrPrototypeInfoOffset() +
            self.heap.TaggedPointerSize())

  def CodeCacheOffset(self):
    return self.DescriptorsOffset() + self.heap.TaggedPointerSize()

  def DependentCodeOffset(self):
    return self.CodeCacheOffset() + self.heap.TaggedPointerSize()