Ruby B. Lee, A. Murat Fiskiran, Zhijie Shi and Xiao Yang, "Refining Instruction Set Architecture for (original) (raw)
Multimedia processing in software has been significantly accelerated by the addition of subword-parallel instructions to the instruction set architectures (ISAs) of modern microprocessors. While some of these multimedia instructions are simple and effective, others are very complex, requiring large, special-purpose functional units that are not practical for constrained environments such as handheld multimedia information appliances. For such environments, low-power and low-cost are as important as the high performance required for real-time multimedia processing and the general-purpose programmability required to support an ever growing range of applications. In this paper, we introduce PLX, a concise ISA that selects the most useful features from the first two generations of multimedia instructions added to microprocessors, and explores new ISA features for high-performance yet low-cost multimedia processing with small footprint processors. PLX is unique in that it is designed from scratch as a fully subword-parallel architecture with novel features like datapath scalability from 32-bit to 128-bit words, and a new definition of predication for reducing conditional branches. We illustrate the use of PLX's architectural features with four frequently used multimedia kernels: discrete cosine transform, pixel padding, clip test and median filter. Our performance results show that a 64-bit PLX implementation achieves significant speedups compared to a basic 64-bit RISC processor and to IA-32 processors with MMX and SSE multimedia extensions. PLX's datapath scalability feature often provides an additional 2x speedup in a cost-effective way.
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