And, of course, the obligatory NB about C-style for- or foreach-loops versus Perl-style: IMHO, the loops in the OPed code are better as:

my $arrayref = ...;

for my $i (0 .. $#$arrayref) {
    for my $j (0 .. $#$arrayref) {
        do_something_with($i, $j);
        }
    }
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