nargs := make([]string, 0, len(args)+len(extraArgs))
	for _, arg := range args {
		if !strings.HasPrefix(arg, "-O") {
			nargs = append(nargs, arg)
		}
	}

	// Force -O0 optimization and append extra arguments, but keep the
	// trailing "-" at the end.
	li := len(nargs) - 1
	last := nargs[li]
	nargs[li] = "-O0"
	nargs = append(nargs, extraArgs...)