$ perl -MO=Concise,-exec -e'BEGIN { *CORE::GLOBAL::time = sub {} } time()'
1  <0> enter
2  <;> nextstate(main 3 -e:1) v
3  <0> pushmark s
4  <#> gv[*CORE::GLOBAL::time] s        <-- sub name
5  <1> entersub[t2] vKS/TARG,1          <-- sub invocation
6  <@> leave[1 ref] vKP/REFC
-e syntax OK