[Isolates] Add debugging code to ensure consistent Isolate class layout.

src/isolate.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 651 matching lines @@
 
   char* ArchiveThread(char* to);
   char* RestoreThread(char* from);
 
   static const char* const kStackOverflowMessage;
 
   static const int kUC16AlphabetSize = 256;  // See StringSearchBase.
   static const int kBMMaxShift = 250;        // See StringSearchBase.
 
   // Accessors.
-#define GLOBAL_ACCESSOR(type, name, initialvalue)                              \
-  type name() const { return name##_; }                                        \
-  void set_##name(type value) { name##_ = value; }
+#define GLOBAL_ACCESSOR(type, name, initialvalue)                       \
+  inline type name() const {                                            \
+    ASSERT(OFFSET_OF(Isolate, name##_) == name##_debug_offset_);        \
+    return name##_;                                                     \
+  }                                                                     \
+  inline void set_##name(type value) {                                  \
+    ASSERT(OFFSET_OF(Isolate, name##_) == name##_debug_offset_);        \
+    name##_ = value;                                                    \
+  }
   ISOLATE_INIT_LIST(GLOBAL_ACCESSOR)
 #undef GLOBAL_ACCESSOR
 
-#define GLOBAL_ARRAY_ACCESSOR(type, name, length)                              \
-  type* name() { return &(name##_[0]); }
+#define GLOBAL_ARRAY_ACCESSOR(type, name, length)                       \
+  inline type* name() {                                                 \
+    ASSERT(OFFSET_OF(Isolate, name##_) == name##_debug_offset_);        \
+    return &(name##_)[0];                                               \
+  }
   ISOLATE_INIT_ARRAY_LIST(GLOBAL_ARRAY_ACCESSOR)
 #undef GLOBAL_ARRAY_ACCESSOR
 
 #define GLOBAL_CONTEXT_FIELD_ACCESSOR(index, type, name)      \
   Handle<type> name() {                                       \
     return Handle<type>(context()->global_context()->name()); \
   }
   GLOBAL_CONTEXT_FIELDS(GLOBAL_CONTEXT_FIELD_ACCESSOR)
 #undef GLOBAL_CONTEXT_FIELD_ACCESSOR
 
@@ skipping 393 matching lines @@
 #define GLOBAL_BACKING_STORE(type, name, initialvalue)                         \
   type name##_;
   ISOLATE_INIT_LIST(GLOBAL_BACKING_STORE)
 #undef GLOBAL_BACKING_STORE
 
 #define GLOBAL_ARRAY_BACKING_STORE(type, name, length)                         \
   type name##_[length];
   ISOLATE_INIT_ARRAY_LIST(GLOBAL_ARRAY_BACKING_STORE)
 #undef GLOBAL_ARRAY_BACKING_STORE
 
+#ifdef DEBUG
+  // This class is huge and has a number of fields controlled by
+  // preprocessor defines. Make sure the offsets of these fields agree
+  // between compilation units.
+#define ISOLATE_FIELD_OFFSET(type, name, ignored)                              \
+  static const intptr_t name##_debug_offset_;
+  ISOLATE_INIT_LIST(ISOLATE_FIELD_OFFSET)
+  ISOLATE_INIT_ARRAY_LIST(ISOLATE_FIELD_OFFSET)
+#undef ISOLATE_FIELD_OFFSET
+#endif
+
   friend class ExecutionAccess;
   friend class IsolateInitializer;
   friend class v8::Isolate;
   friend class v8::Locker;
 
   DISALLOW_COPY_AND_ASSIGN(Isolate);
 };
 
 
 // If the GCC version is 4.1.x or 4.2.x an additional field is added to the
@@ skipping 163 matching lines @@
 
 } }  // namespace v8::internal
 
 // TODO(isolates): Get rid of these -inl.h includes and place them only where
 //                 they're needed.
 #include "allocation-inl.h"
 #include "zone-inl.h"
 #include "frames-inl.h"
 
 #endif  // V8_ISOLATE_H_