Cooperation of global and local register allocators for better handling of procedures

A method and device for optimizing a compiler involves cooperation between the global and local register allocators in assigning symbolic registers to hardware registers. A large procedure may have many associated symbolic registers; the invention involves partitioning the symbolic registers into at least two portions, and allowing the global register allocator to assign one portion and the local register allocator to assign another portion. The registers may be partitioned based on different criteria, such as local vs. global registers, or spill costs, or shallow vs. nested regions.