Support fast-path allocation for subclass constructors with correctly initialized initial maps.

src/objects.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/allocation.h"
@@ skipping 5561 matching lines @@
   // Builtins::kJSConstructStubGeneric stub.
   // This counter is used for in-object slack tracking and for map aging.
   // The in-object slack tracking is considered enabled when the counter is
   // in the range [kSlackTrackingCounterStart, kSlackTrackingCounterEnd].
   class Counter : public BitField<int, 28, 4> {};
   static const int kSlackTrackingCounterStart = 14;
   static const int kSlackTrackingCounterEnd = 8;
   static const int kRetainingCounterStart = kSlackTrackingCounterEnd - 1;
   static const int kRetainingCounterEnd = 0;
 
+  // Completes inobject slack tracking for the transition tree starting at this
+  // initial map.
+  void CompleteInobjectSlackTracking();
+
   // 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 the instance has a [[Construct]] internal method.
   // This property is implemented according to ES6, section 7.2.4.
@@ skipping 5168 matching lines @@
     }
     return value;
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #endif  // V8_OBJECTS_H_