Register Allocation for Banked Register File

摘要

A banked register file is a register file partitioned into banks. A register in a banked register file is addressed with the register number in conjunction with the active bank number. A banked register file may be employed to reduce the number of bits for register operands in the instruction encoding at the cost of bank changes and inter-bank data transfers. Although a banked register file is introduced to provide sufficient registers and reduce memory traffic, it may on the other hand inflate code by unwanted bank changes and excessive inter-bank data movements. In this context, code quality heavily depends on the register allocator that decides the location of each variable. This paper addresses a heuristic approach to register allocation for exploiting two register banks. It performs global register allocation with the primary bank registers, while reducing the register pressure by doing local register allocation with the secondary bank registers. Experimental results show that the proposed register allocator eliminates a significant amount of memory traffic while achieving smaller code size compared to an allocator that utilizes the primary bank only.