Use the return value of vm native methods to set the return value,

vm/native_arguments.h

Index: vm/native_arguments.h
===================================================================
--- vm/native_arguments.h	(revision 11327)
+++ vm/native_arguments.h	(working copy)
@@ -66,6 +66,10 @@
 
   void SetReturn(const Object& value) const;
 
+  // If this function is misused, it could cause corruption.  You may
+  // only use this if Siva says it is ok.
+  void SetReturnUnsafe(RawObject* value) const;

[Ivan Posva, 2012/08/27 18:20:37]

Can we make this a private and do some friend magic instead of purely relying on
the comment?

[turnidge, 2012/08/28 18:08:21]

I tried it but it got a little bit involved.

In order to declare the functions as friend declarations, we need access to the
BOOTSTRAP_NATIVE_LIST in bootstrap_natives.h.  Because that file also includes
the forward declarations of the native entries, it includes native_entry.h  And,
in turn, native_entry.h includes native_arguments.h in order to get the
definition of the NativeArguments type (it needs the full definition because it
is passed by value).

So, to resolve this, I would need to do some refactoring.  I would probably need
to split the BOOTSTRAP_NATIVE_LIST macro and the native entry forward
declarations into two separate headers.  I started to do this, but I decided I
should ping you back to see what you'd like me to do.

[turnidge, 2012/08/29 20:36:49]

As you suggested offline, I've created a BootstrapNatives class containing all
of the native entries.  That made the friend declaration quite a bit simpler.

On 2012/08/28 18:08:21, turnidge wrote:

+
   static intptr_t isolate_offset() {
     return OFFSET_OF(NativeArguments, isolate_);
   }