#!perl 
use strict;
use Benchmark;

sub normal {
    return 0 unless $_[0];
    @_ = ($_[0] - 1);
    return normal(@_);
}

sub tail {
    return 0 unless $_[0];
    @_ = ($_[0] - 1);
    goto &tail;
}

timethese( 10, {
        "normal" => sub { normal(500000) },
        "tail"   => sub {   tail(500000) },
    }
);