Better support for 'polymorphic' JS and external arrays

src/x64/macro-assembler-x64.h

 // Copyright 2011 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 728 matching lines @@
   void CmpInstanceType(Register map, InstanceType type);
 
   // Check if the map of an object is equal to a specified map and
   // branch to label if not. Skip the smi check if not required
   // (object is known to be a heap object)
   void CheckMap(Register obj,
                 Handle<Map> map,
                 Label* fail,
                 bool is_heap_object);
 
+  // Check if the map of an object is equal to a one of a specified lists map
+  // and branch to label if not. Skip the smi check if not required (object is
+  // known to be a heap object)
+  void CheckMaps(Register obj,
+                 ZoneMapList* maps,
+                 Label* fail,
+                 bool is_heap_object);
+
   // Check if the object in register heap_object is a string. Afterwards the
   // register map contains the object map and the register instance_type
   // contains the instance_type. The registers map and instance_type can be the
   // same in which case it contains the instance type afterwards. Either of the
   // registers map and instance_type can be the same as heap_object.
   Condition IsObjectStringType(Register heap_object,
                                Register map,
                                Register instance_type);
 
   // FCmp compares and pops the two values on top of the FPU stack.
@@ skipping 1248 matching lines @@
       Jump(adaptor, RelocInfo::CODE_TARGET);
     }
     bind(&invoke);
   }
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_MACRO_ASSEMBLER_X64_H_