$ perl -MO=Concise -E'BEGIN { *DUMMY::GLOBAL::caller = sub {} }; caller()'
4  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 49 -e:1) v:%,{,2048 ->3
3     <0> caller[t1] v* ->4
-e syntax OK
$ perl -MO=Concise -E'BEGIN { *CORE::GLOBAL::caller = sub {} }; caller()'
6  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 49 -e:1) v:%,{,2048 ->3
5     <1> entersub[t3] vKS/TARG,1 ->6
-        <1> ex-list K ->5
3           <0> pushmark s ->4
-           <1> ex-rv2cv sK ->-
4              <#> gv[*CORE::GLOBAL::caller] s ->5
-e syntax OK