Demand-Driven Register Allocation

A new global register allocation technique, demand-driven register allocation, is described. Demand-driven register allocation quantifies the costs and benefits of allocating variables to registers over live ranges so that high-quality allocations can be made. Local allocation is done first, and then global allocation is done iteratively beginning in the the most deeply nested loops. Because local allocation precedes global allocation, demand-driven allocation does not interfere with the use of well-known, high-quality local register allocation and instruction-scheduling techniques.