RingScalar: A Complexity-Effective Out-of-Order Superscalar Microarchitecture

RingScalar is a complexity-effective microarchitecture for out-of-order superscalar processors, that reduces the area, latency, and power of all major structures in the instruction flow. The design divides an -way superscalar into columns connected in a unidirectional ring, where each column contains a portion of the instruction window, a bank of the register file, and an ALU. The design exploits the fact that most decoded instructions are waiting on just one operand to use only a single tag per issue window entry, and to restrict instruction wakeup and value bypass to only communicate with the neighboring column. Detailed simulations of fourissue single-threaded machines running SPECint2000 show that RingScalar has IPC only 13% lower than an idealized superscalar, while providing large reductions in area, power, and circuit latency.

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