I have an interpretation for your results but no time for a formal proove.

At compiletime the pads for the lexicals $x and $y are associated to the sub. With a recursiv call perl has to allocate a new pad for the function, instead of reusing the old one.

Furthermore the if-branches are optimised away, so no "my $x" is executed at runtime to resetting $x to undef, so your accessing in 2 and 4 the last setting in the same level.

in short, it's one of these strange side effects of optimising code away, using B:Deparse you will most probably code-chunks missing.

you can also try this, which results in an error 

goto label;
if (0) {
  label: print "huhu";
}

[download]
(untested)

so be aware of optimised code-chunks.

In reply to Re: Confusion over scope of "my" vars by Anonymous Monk
in thread Confusion over scope of "my" vars by Anonymous Monk

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