When return is the last op of a function, is there a reason it isn't removed from the tree such that 
>perl -MO=Concise,f -e"sub f { return $x }"
main::f:
5  <1> leavesub[1 ref] K/REFC,1 ->(end)
-     <@> lineseq KP ->5
1        <;> nextstate(main 1 -e:1) v ->2
4        <@> return K ->5
2           <0> pushmark s ->3
-           <1> ex-rv2sv sK/1 ->4
3              <#> gvsv[*x] s ->4
-e syntax OK

[download]

looks like 

main::f:
3  <1> leavesub[1 ref] K/REFC,1 ->(end)
-     <@> lineseq KP ->5
1        <;> nextstate(main 1 -e:1) v ->2
-        <@> ex-return K ->-
-           <0> ex-pushmark s ->-
-           <1> ex-rv2sv sK/1 ->-
2              <#> gvsv[*x] s ->3
-e syntax OK

[download]

which would be equivalent to 

>perl -MO=Concise,f -e"sub f { $x }"
main::f:
3  <1> leavesub[1 ref] K/REFC,1 ->(end)
-     <@> lineseq KP ->3
1        <;> nextstate(main 1 -e:1) v ->2
-        <1> ex-rv2sv sK/1 ->-
2           <#> gvsv[*x] s ->3
-e syntax OK

[download]

Just curious. There's no speed penalty to leaving it in 

5.8.8:
           Rate implicit explicit
implicit 980/ms       --      -0%
explicit 984/ms       0%       --

5.10.0:
            Rate explicit implicit
explicit 1000/ms       --      -0%
implicit 1004/ms       0%       --

[download]

Benchmark code

In reply to Why isn't return removed from optree? by ikegami

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