Preheat oven to 350°. With a small sharp knife, make several small incisions in the roast; insert a sliver of garlic in each incision. If desired, rub the roast with oil. Then sprinkle over it the rosemary, salt and pepper.
Place the roast in a shallow roasting pan; pour 1/4 cup of the wine into the pan.
Roast, basting occasionally with the pan juices (adding 1/4 cup of the wine after half an hour, and the other 1/4 cup a few minutes before the roast is done), until cooked through and an instant-read thermometer inserted in the pork (not touching bone) registers 160°, about 1 3/4 hours.