Call-cost directed register allocation

Abstract

Choosing the right kind of register for a live range plays a major role in eliminating the register-allocation overhead when the compiled function is frequently executed or function tails are on the most frequently executed paths. Picking the wrong kind of register for a live range incurs a high penalty that may dominate the total overhead of register allocation. In this paper, we present three improvements, storage-class analysis, benefit-driven simplification, and preference decision that are effective in selecting the right kind of register for a live range. Then we compare an enhanced Chaitin-style register allocator (with these three improvements) with priority-based and optimistic coloring.