tigress --Environment=x86_64:Darwin:Clang:5.1 --Verbosity=1  \
   --Transform=Virtualize --Functions=fib --VirtualizeDispatch=switch \
   --VirtualizeMaxDuplicateOps=2 --VirtualizeOperands=mixed \
   --Transform=CleanUp --CleanUpKinds=annotations \
   --out=gen/virtualize_mixed.c test1.c