Multithreading of self-modifying
#1 sethi %hi(5),%o0
#2 call new
#3 or %o0,%lo(5),%o0
#1 ba,a #1
! spin lock
#2 call new
#3 or %o0,%lo(5),%o0
Release lock
#1 sethi %hi(class_obj),%o0
#2 call new_quick
#3 or %o0,%lo(class_obj),%o0
#4