[runtime] Add GCHandle pointer-sized API.

runtime/mono-runtime.h.t4

@@ -294,6 +294,16 @@ bool
 <#= export.EntryPoint #>_exists ();
 
 <# } #>
+
+/*
+ * Wrapper GCHandle functions that takes pointer sized handles instead of ints,
+ * so that we can adapt our code incrementally to use pointers instead of ints
+ * until Mono's pointer-sized API is available for us.
+ * Ref: https://github.com/dotnet/runtime/commit/3886a63841434af716292172737a42757a15c6a6
+ */
+#define INVALID_GCHANDLE 0
+typedef void* GCHandle;
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif

runtime/runtime.m

@@ -2666,6 +2666,48 @@ xamarin_get_managed_method_for_token (guint32 token_ref, guint32 *exception_gcha
 	return xamarin_get_reflection_method_method (reflection_method);
 }
 
+GCHandle
+xamarin_gchandle_new (MonoObject *obj, bool track_resurrection)
+{
+	if (obj == NULL)
+		return INVALID_GCHANDLE;
+	return GINT_TO_POINTER (mono_gchandle_new (obj, track_resurrection));
+}
+
+GCHandle
+xamarin_gchandle_new_weakref (MonoObject *obj, bool pinned)
+{
+	if (obj == NULL)
+		return INVALID_GCHANDLE;
+	return GINT_TO_POINTER (mono_gchandle_new_weakref (obj, pinned));
+}
+
+MonoObject *
+xamarin_gchandle_get_target (GCHandle handle)
+{
+	if (handle == INVALID_GCHANDLE)
+		return NULL;
+	return mono_gchandle_get_target (GPOINTER_TO_UINT (handle));
+}
+
+void
+xamarin_gchandle_free (GCHandle handle)
+{
+	if (handle == INVALID_GCHANDLE)
+		return;
+	mono_gchandle_free (GPOINTER_TO_UINT (handle));
+}
+
+MonoObject *
+xamarin_gchandle_unwrap (GCHandle handle)
+{
+	if (handle == INVALID_GCHANDLE)
+		return NULL;
+	MonoObject *rv = mono_gchandle_get_target (GPOINTER_TO_UINT (handle));
+	mono_gchandle_free (GPOINTER_TO_UINT (handle));
+	return rv;
+}
+
 /*
  * Object unregistration:
  *

runtime/xamarin/runtime.h

@@ -260,6 +260,18 @@ void			xamarin_printf (const char *format, ...);
 void			xamarin_vprintf (const char *format, va_list args);
 void			xamarin_install_log_callbacks ();
 
+/*
+ * Wrapper GCHandle functions that takes pointer sized handles instead of ints,
+ * so that we can adapt our code incrementally to use pointers instead of ints
+ * until Mono's pointer-sized API is available for us.
+ * Ref: https://github.com/dotnet/runtime/commit/3886a63841434af716292172737a42757a15c6a6
+ */
+GCHandle		xamarin_gchandle_new (MonoObject *obj, bool track_resurrection);
+GCHandle		xamarin_gchandle_new_weakref (MonoObject *obj, bool pinned);
+MonoObject *	xamarin_gchandle_get_target (GCHandle handle);
+void			xamarin_gchandle_free (GCHandle handle);
+MonoObject *	xamarin_gchandle_unwrap (GCHandle handle); // Will get the target and free the GCHandle
+
 /*
  * Look for an assembly in the app and open it.
  *