Remember and reuse derived map for external arrays

src/v8globals.h

 // Copyright 2010 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 300 matching lines @@
   OWN_MAP,  // For fast properties objects.
   PROTOTYPE_MAP  // For slow properties objects (except GlobalObjects).
 };
 
 
 // Type of properties.
 // Order of properties is significant.
 // Must fit in the BitField PropertyDetails::TypeField.
 // A copy of this is in mirror-debugger.js.
 enum PropertyType {
-  NORMAL              = 0,  // only in slow mode
-  FIELD               = 1,  // only in fast mode
-  CONSTANT_FUNCTION   = 2,  // only in fast mode
-  CALLBACKS           = 3,
-  INTERCEPTOR         = 4,  // only in lookup results, not in descriptors.
-  MAP_TRANSITION      = 5,  // only in fast mode
-  CONSTANT_TRANSITION = 6,  // only in fast mode
-  NULL_DESCRIPTOR     = 7,  // only in fast mode
+  NORMAL                    = 0,  // only in slow mode
+  FIELD                     = 1,  // only in fast mode
+  CONSTANT_FUNCTION         = 2,  // only in fast mode
+  CALLBACKS                 = 3,
+  INTERCEPTOR               = 4,  // only in lookup results, not in descriptors.
+  MAP_TRANSITION            = 5,  // only in fast mode
+  EXTERNAL_ARRAY_TRANSITION = 6,
+  CONSTANT_TRANSITION       = 7,  // only in fast mode
+  NULL_DESCRIPTOR           = 8,  // only in fast mode
   // All properties before MAP_TRANSITION are real.
   FIRST_PHANTOM_PROPERTY_TYPE = MAP_TRANSITION,
   // There are no IC stubs for NULL_DESCRIPTORS. Therefore,
   // NULL_DESCRIPTOR can be used as the type flag for IC stubs for
   // nonexistent properties.
   NONEXISTENT = NULL_DESCRIPTOR
 };
 
 
 // Whether to remove map transitions and constant transitions from a
@@ skipping 132 matching lines @@
 
 // The Strict Mode (ECMA-262 5th edition, 4.2.2).
 enum StrictModeFlag {
   kNonStrictMode,
   kStrictMode
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_V8GLOBALS_H_