U32 is_utf8 = SvUTF8(cv);
C<SvPVX(cv)> contains just the sub name itself, not including the package.
+For an AUTOLOAD routine in UNIVERSAL or one of its superclasses,
+C<CvSTASH(cv)> returns NULL during a method call on a nonexistent package.
B<Note>: Setting $AUTOLOAD stopped working in 5.6.1, which did not support
XS AUTOLOAD subs at all. Perl 5.8.0 introduced the use of fields in the