fib.java

    @JRubyMethod(name = "fib_ruby", frame = true, required = 1, optional = 0, rest = false)
    public static IRubyObject method__0$RUBY$fib_ruby(
                                                      final bench_fib_recursive bench_fib_recursive,
                                                      final ThreadContext threadContext,
                                                      final IRubyObject rubyObject,
                                                      final IRubyObject rubyObject2,
                                                      final Block block) {
                                                        
        if (bench_fib_recursive.getCallSite1().call(threadContext, rubyObject, rubyObject2, 2L).isTrue()) {
            return rubyObject2
        } else {
            return bench_fib_recursive.getCallSite2().call(threadContext, rubyObject,
                        bench_fib_recursive.getCallSite3().call(threadContext, rubyObject, rubyObject,
                                bench_fib_recursive.getCallSite4().call(threadContext, rubyObject, rubyObject2, 2L)),
                        bench_fib_recursive.getCallSite5().call(threadContext, rubyObject, rubyObject,
                                bench_fib_recursive.getCallSite6().call(threadContext, rubyObject, rubyObject2, 1L)));
        }
    }

fib.ruby

def fib_ruby(a)
  if a < 2
    a
  else
    fib(a - 1) + fib(a - 2)
  end
end