[Atomics] code stubs for atomic operations

src/objects.h

 // Copyright 2015 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/assert-scope.h"
@@ skipping 291 matching lines @@
 // ICs store extra state in a Code object. The default extra state is
 // kNoExtraICState.
 typedef int ExtraICState;
 static const ExtraICState kNoExtraICState = 0;
 
 // Instance size sentinel for objects of variable size.
 const int kVariableSizeSentinel = 0;
 
 // We may store the unsigned bit field as signed Smi value and do not
 // use the sign bit.
-const int kStubMajorKeyBits = 7;
+const int kStubMajorKeyBits = 8;
 const int kStubMinorKeyBits = kSmiValueSize - kStubMajorKeyBits - 1;
 
 // All Maps have a field instance_type containing a InstanceType.
 // It describes the type of the instances.
 //
 // As an example, a JavaScript object is a heap object and its map
 // instance_type is JS_OBJECT_TYPE.
 //
 // The names of the string instance types are intended to systematically
 // mirror their encoding in the instance_type field of the map.  The default
@@ skipping 10445 matching lines @@
     }
     return value;
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #endif  // V8_OBJECTS_H_