prelude: |
  class C
    @a = 1
    def self.a
      _a = @a; _a = @a; _a = @a; _a = @a; _a = @a;
      _a = @a; _a = @a; _a = @a; _a = @a; _a = @a;
    end
  end
benchmark:
  vm_ivar_of_class: |
    a = C.a
loop_count: 30000000