Efficient masking techniques for large-scale SIMD architectures

SIMD (single-instruction-stream, multiple-data-stream) architectures require mechanisms that efficiently enable and disable mask processors to support flexible programming. Most current SIMD architectures use local masking. Global processor masks, specified by the control unit, are more efficient for tasks where the masking is data independent. An efficient hybrid masking technique that supports global masking, as well as local masking, for SIMD architectures constructed from standard microprocessors is proposed. A design for the hybrid mechanism is described, and its experimental performance using the existing PASM prototype is examined. It is shown that the hybrid masking technique can increase the utilization of PEs and thus increase performance, the degree of improvement being algorithm dependent