Count the number of YARV instructions in source

count.rb

def count(iseq)
  iseq[12].select { _1 in [:ensure | :rescue, *] }.sum { count(_1[1]) } +
  iseq[13].sum do
    case _1
    in Integer | Symbol
      0
    in [*, ["YARVInstructionSequence/SimpleDataFormat", *] => child, *]
      1 + count(child)
    in Array
      1
    end
  end
end

p count(RubyVM::InstructionSequence.compile(ARGF.read).to_a)