var b bytes.Buffer
	fmt.Fprintln(&b, "// Code generated by mksizeclasses.go; DO NOT EDIT.")
	fmt.Fprintln(&b, "//go:generate go run mksizeclasses.go")
	fmt.Fprintln(&b)
	fmt.Fprintln(&b, "package runtime")
	classes := makeClasses()

	printComment(&b, classes)

	printClasses(&b, classes)

	out, err := format.Source(b.Bytes())
	if err != nil {
		log.Fatal(err)
	}
	if *stdout {
		_, err = os.Stdout.Write(out)
	} else {