Pour the can of cherry pie filling into a deep dish baking dish. (You may use an oblong Pyrex dish.) In a large mixing bowl, combine the white cake mix with the margarine using a pastry blender (or fork). When the mixture is roughly the consistency of cornmeal, add the 1 cup of pecans and mix together. Sprinkle this mixture evenly over the pie filling in the deep dish. Place in a 350 degree oven for about 20 minutes. Increase or decrease the cooking time, so that it is browned to your liking. Enjoy!