Increasing the Instruction Fetch Rate via Block-Structured Instruction Set Architectures - Microarchitecture, 1996., IEEE/ACM International Symposium on

To exploit larger amounts of instruction level parallelism, processors are being built with wider issue widths and larger numbers offunctional units. Instruction fetch rate must also be increased in order to effectively exploit the performance potential of such processors. Block-structured ISAs provide an effective means of increasing the instruction fetch rate. We define an optimization, called block enlargement, that can be applied to a block-structured ISA to increase the instruction fetch rate of a processor that implements that ISA. We have constructed a compiler that generates block-structured ISA code, and a simulator that models the execution of that code on a block-structured ISA processox We show that for the SPECint95 benchmarks, the blockstructured ISA processor executing enlarged atomic blocks outperforms a conventional ISA processor by 12% while using simpler microarchitectural mechanisms to support wideissue and dynamic scheduling.