Allow smis for singleton types

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 107 matching lines @@
 //               - ExternalAsciiInternalizedString
 //               - ExternalTwoByteInternalizedString
 //         - Symbol
 //       - HeapNumber
 //       - Code
 //       - Map
 //       - Oddball
 //       - Foreign
 //       - SharedFunctionInfo
 //       - Struct
+//         - Box
 //         - DeclaredAccessorDescriptor
 //         - AccessorInfo
 //           - DeclaredAccessorInfo
 //           - ExecutableAccessorInfo
 //         - AccessorPair
 //         - AccessCheckInfo
 //         - InterceptorInfo
 //         - CallHandlerInfo
 //         - TemplateInfo
 //           - FunctionTemplateInfo
@@ skipping 203 matching lines @@
   V(EXTERNAL_INTERNALIZED_STRING_WITH_ONE_BYTE_DATA_TYPE)                      \
   V(SHORT_EXTERNAL_INTERNALIZED_STRING_TYPE)                                   \
   V(SHORT_EXTERNAL_ASCII_INTERNALIZED_STRING_TYPE)                             \
   V(SHORT_EXTERNAL_INTERNALIZED_STRING_WITH_ONE_BYTE_DATA_TYPE)                \
                                                                                \
   V(SYMBOL_TYPE)                                                               \
   V(MAP_TYPE)                                                                  \
   V(CODE_TYPE)                                                                 \
   V(ODDBALL_TYPE)                                                              \
   V(JS_GLOBAL_PROPERTY_CELL_TYPE)                                              \
+  V(BOX_TYPE)                                                                  \
                                                                                \
   V(HEAP_NUMBER_TYPE)                                                          \
   V(FOREIGN_TYPE)                                                              \
   V(BYTE_ARRAY_TYPE)                                                           \
   V(FREE_SPACE_TYPE)                                                           \
   /* Note: the order of these external array */                                \
   /* types is relied upon in */                                                \
   /* Object::IsExternalArray(). */                                             \
   V(EXTERNAL_BYTE_ARRAY_TYPE)                                                  \
   V(EXTERNAL_UNSIGNED_BYTE_ARRAY_TYPE)                                         \
@@ skipping 158 matching lines @@
 // A struct is a simple object a set of object-valued fields.  Including an
 // object type in this causes the compiler to generate most of the boilerplate
 // code for the class including allocation and garbage collection routines,
 // casts and predicates.  All you need to define is the class, methods and
 // object verification routines.  Easy, no?
 //
 // Note that for subtle reasons related to the ordering or numerical values of
 // type tags, elements in this list have to be added to the INSTANCE_TYPE_LIST
 // manually.
 #define STRUCT_LIST_ALL(V)                                                     \
+  V(BOX, Box, box)                                                             \
   V(DECLARED_ACCESSOR_DESCRIPTOR,                                              \
     DeclaredAccessorDescriptor,                                                \
     declared_accessor_descriptor)                                              \
   V(DECLARED_ACCESSOR_INFO, DeclaredAccessorInfo, declared_accessor_info)      \
   V(EXECUTABLE_ACCESSOR_INFO, ExecutableAccessorInfo, executable_accessor_info)\
   V(ACCESSOR_PAIR, AccessorPair, accessor_pair)                                \
   V(ACCESS_CHECK_INFO, AccessCheckInfo, access_check_info)                     \
   V(INTERCEPTOR_INFO, InterceptorInfo, interceptor_info)                       \
   V(CALL_HANDLER_INFO, CallHandlerInfo, call_handler_info)                     \
   V(FUNCTION_TEMPLATE_INFO, FunctionTemplateInfo, function_template_info)      \
@@ skipping 121 matching lines @@
       SHORT_EXTERNAL_STRING_WITH_ONE_BYTE_DATA_TYPE | kInternalizedTag,
 
   // Non-string names
   SYMBOL_TYPE = kNotStringTag,  // LAST_NAME_TYPE, FIRST_NONSTRING_TYPE
 
   // Objects allocated in their own spaces (never in new space).
   MAP_TYPE,
   CODE_TYPE,
   ODDBALL_TYPE,
   JS_GLOBAL_PROPERTY_CELL_TYPE,
+  BOX_TYPE,
 
   // "Data", objects that cannot contain non-map-word pointers to heap
   // objects.
   HEAP_NUMBER_TYPE,
   FOREIGN_TYPE,
   BYTE_ARRAY_TYPE,
   FREE_SPACE_TYPE,
   EXTERNAL_BYTE_ARRAY_TYPE,  // FIRST_EXTERNAL_ARRAY_TYPE
   EXTERNAL_UNSIGNED_BYTE_ARRAY_TYPE,
   EXTERNAL_SHORT_ARRAY_TYPE,
@@ skipping 4998 matching lines @@
 // An abstract superclass, a marker class really, for simple structure classes.
 // It doesn't carry much functionality but allows struct classes to be
 // identified in the type system.
 class Struct: public HeapObject {
  public:
   inline void InitializeBody(int object_size);
   static inline Struct* cast(Object* that);
 };
 
 
+// A simple one-element struct, useful where smis need to be boxed.
+class Box : public Struct {
+ public:
+  // [value]: the boxed contents.
+  DECL_ACCESSORS(value, Object)
+
+  static inline Box* cast(Object* obj);
+
+  // Dispatched behavior.
+  DECLARE_PRINTER(Box)
+  DECLARE_VERIFIER(Box)
+
+  static const int kValueOffset = HeapObject::kHeaderSize;
+  static const int kSize = kValueOffset + kPointerSize;
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(Box);
+};
+
+
 // Script describes a script which has been added to the VM.
 class Script: public Struct {
  public:
   // Script types.
   enum Type {
     TYPE_NATIVE = 0,
     TYPE_EXTENSION = 1,
     TYPE_NORMAL = 2
   };
 
@@ skipping 3920 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_