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

vm/native_entry.h

Index: vm/native_entry.h
===================================================================
--- vm/native_entry.h	(revision 11327)
+++ vm/native_entry.h	(working copy)
@@ -33,7 +33,8 @@
 
 
 #define DEFINE_NATIVE_ENTRY(name, argument_count)                              \
-  static void DN_Helper##name(Isolate* isolate, NativeArguments* arguments);   \
+  static RawObject* DN_Helper##name(Isolate* isolate,                          \
+                                    NativeArguments* arguments);               \
   void NATIVE_ENTRY_FUNCTION(name)(Dart_NativeArguments args) {                \
     CHECK_STACK_ALIGNMENT;                                                     \
     VERIFY_ON_TRANSITION;                                                      \
@@ -43,11 +44,13 @@
     {                                                                          \
       Zone zone(arguments->isolate());                                         \
       HANDLESCOPE(arguments->isolate());                                       \
-      DN_Helper##name(arguments->isolate(), arguments);                        \
+      arguments->SetReturnUnsafe(                                              \
+          DN_Helper##name(arguments->isolate(), arguments));                   \

[siva, 2012/08/28 18:21:20]

I was also proposing that we set the return value in the stub code so that there
would be no need for this SetReturnUnsafe function.

These native functions would return Raw<type>* just like all regular VM
functions and the stub code has access to arguments area it would just store the
return value into that return area of arguments.

Only if the VERIFY_ON_TRANSITION FLAG is on we would need to  store the return
value in a handle do the verification and then return.

     }                                                                          \
     VERIFY_ON_TRANSITION;                                                      \
   }                                                                            \
-  static void DN_Helper##name(Isolate* isolate, NativeArguments* arguments)
+  static RawObject* DN_Helper##name(Isolate* isolate,                          \
+                                    NativeArguments* arguments)
 
 
 #define DECLARE_NATIVE_ENTRY(name, argument_count)                             \