It shows up as const AV in the opcode tree.

You can prove the list is flattened once using

for (1..2) {
   for ((), 4..8) {
      say $_++;
   }
}
[download]

Update: Added missing parens.

But the 100k scalars don't show up in the optree. Where are they?

Perl 6 - second systems done right

I don't know why B::Concise doesn't dump the contents of array, but B::Concise does show that the array is in the optree.

$ perl -MO=Concise,-exec -e'my @a = 1..1000'
1  <0> enter 
2  <;> nextstate(main 1 -e:1) v:{
3  <0> pushmark s
4  <$> const[AV ] s
              ^
              |

5  <1> rv2av lKP/1
6  <0> pushmark s
7  <0> padav[@a:1,2] lRM*/LVINTRO
8  <2> aassign[t4] vKS/COMMON
9  <@> leave[1 ref] vKP/REFC
-e syntax OK
[download]

It shows up as const AV in the opcode tree.

You can prove the list is flattened once using

I see the 1 & 2, and 4 & 8 as consts, but I'm also seeing what look to me like two loops. Perhaps you can interpret it better?:

c:\test>perl -MO=Concise
for (1..2) {
    for (4..8) {
       say $_++;
    }
 }
^Z
t  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 4 -:1) v:{ ->3
s     <2> leaveloop vK/2 ->t
7        <{> enteriter(next->p last->s redo->8) lKS/8 ->q
-           <0> ex-pushmark s ->3
-           <1> ex-list lK ->6
3              <0> pushmark s ->4
4              <$> const[IV 1] s ->5
5              <$> const[IV 2] s ->6
6           <#> gv[*_] s ->7
-        <1> null vK/1 ->s
r           <|> and(other->8) vK/1 ->s
q              <0> iter s ->r
-              <@> lineseq vKP ->-
8                 <;> nextstate(main 2 -:2) v:{ ->9
o                 <2> leaveloop vK/2 ->p
d                    <{> enteriter(next->l last->o redo->e) lKS/8 ->m
-                       <0> ex-pushmark s ->9
-                       <1> ex-list lK ->c
9                          <0> pushmark s ->a
a                          <$> const[IV 4] s ->b
b                          <$> const[IV 8] s ->c
c                       <#> gv[*_] s ->d
-                    <1> null vK/1 ->o
n                       <|> and(other->e) vK/1 ->o
m                          <0> iter s ->n
-                          <@> lineseq vKP ->-
e                             <;> nextstate(main 1 -:3) v:{ ->f
k                             <1> preinc[t7] vK/1 ->l
j                                <1> entersub[t6] sKRMS/NO(),TARG ->k
f                                   <0> pushmark s ->g
-                                   <1> ex-rv2sv sKM/1 ->h
g                                      <#> gvsv[*_] s ->h
h                                   <$> method_named[PV "say"] s ->i
i                                   <1> rv2cv /NO() ->j
l                             <0> unstack v ->m
p                 <0> unstack v ->q
- syntax OK
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---

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Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

The start of some sanity?

Sorry, there was a set of parens missing. (Fixed.) I was about to reply to your post that for (CONST..CONST) is a counting loop rather than a loop iterating over the result of a range operator. There is no range operator, so the range operator cannot be flattened. Try

perl -e"<>; exit; @a = 1..100000;"
perl -e"<>; exit; for ((), 1..100000) {}"
[download]

Results:

perl -e"<>; exit; for ((),1..   1000) {}    1,252K
perl -e"<>; exit; for ((),1..  10000) {}    1,784K
perl -e"<>; exit; for ((),1.. 100000) {}    6,028K
perl -e"<>; exit; for ((),1..1000000) {}   45,212K
[download]

Update: Added results.