Bryant, Kelvin S.Mauney, JonWe discuss the problems involved in building a retargetable register allocator for use in an optimizing compiler. While the popular "register coloring" method is machine-independent, the allocator as a whole must implement numerous machine-dependent decisions. We present the kinds of information that must be parameterized in order to include register allocation in an retargetable compiler back-end, and discuss a sample solution.en-USTechnical Report