Do deferred migration of maps after deoptimizing once.

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 5617 matching lines @@
   class IsShared:                   public BitField<bool, 22,  1> {};
   class FunctionWithPrototype:      public BitField<bool, 23,  1> {};
   class DictionaryMap:              public BitField<bool, 24,  1> {};
   class OwnsDescriptors:            public BitField<bool, 25,  1> {};
   class IsObserved:                 public BitField<bool, 26,  1> {};
   class Deprecated:                 public BitField<bool, 27,  1> {};
   class IsFrozen:                   public BitField<bool, 28,  1> {};
   class IsUnstable:                 public BitField<bool, 29,  1> {};
   class IsMigrationTarget:          public BitField<bool, 30,  1> {};
 
+  // Bit field 4.
+  inline uint32_t bit_field4();
+  inline void set_bit_field4(uint32_t bits);
+
+  class HasMigrated:        public BitField<int,   0,  1> {};
+
+  inline void set_has_migrated(bool value);
+  inline bool has_migrated();
+
   // Tells whether the object in the prototype property will be used
   // for instances created from this function.  If the prototype
   // property is set to a value that is not a JSObject, the prototype
   // property will not be used to create instances of the function.
   // See ECMA-262, 13.2.2.
   inline void set_non_instance_prototype(bool value);
   inline bool has_non_instance_prototype();
 
   // Tells whether function has special prototype property. If not, prototype
   // property will not be created when accessed (will return undefined),
@@ skipping 530 matching lines @@
   // pointer if unused. When the map has transitions, the back pointer is
   // transferred to the transition array and accessed through an extra
   // indirection.
   static const int kTransitionsOrBackPointerOffset =
       kConstructorOffset + kPointerSize;
   static const int kDescriptorsOffset =
       kTransitionsOrBackPointerOffset + kPointerSize;
   static const int kCodeCacheOffset = kDescriptorsOffset + kPointerSize;
   static const int kDependentCodeOffset = kCodeCacheOffset + kPointerSize;
   static const int kBitField3Offset = kDependentCodeOffset + kPointerSize;
-  static const int kSize = kBitField3Offset + kPointerSize;
+  static const int kBitField4Offset = kBitField3Offset + kPointerSize;
+  static const int kSize = kBitField4Offset + kPointerSize;
 
   // Layout of pointer fields. Heap iteration code relies on them
   // being continuously allocated.
   static const int kPointerFieldsBeginOffset = Map::kPrototypeOffset;
   static const int kPointerFieldsEndOffset = kBitField3Offset + kPointerSize;
 
   // Byte offsets within kInstanceSizesOffset.
   static const int kInstanceSizeOffset = kInstanceSizesOffset + 0;
   static const int kInObjectPropertiesByte = 1;
   static const int kInObjectPropertiesOffset =
@@ skipping 4238 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_