Sub-operation Parallelism Optimization in SIMD Processor Core Synthesis

Hideki KAWAZU  Jumpei UCHIDA  Yuichiro MIYAOKA  Nozomu TOGAWA  Masao YANAGISAWA  Tatsuo OHTSUKI  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E88-A   No.4   pp.876-884
Publication Date: 2005/04/01
Online ISSN: 
DOI: 10.1093/ietfec/e88-a.4.876
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Selected Papers from the 17th Workshop on Circuits and Systems in Karuizawa)
processor synthesis,  packed SIMD type operation,  hardware/software partitioning,  hardware/software cosynthesis,  sub-operation parallelism,  

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A b-bit SIMD functional unit has n k-bit sub-functional units in itself, where b = k n. It can execute n-parallel k-bit operations. However, all the b-bit functional units in a processor core do not necessarily execute n-parallel operations. Depending on an application program, some of them just execute n/2-parallel operations or even n/4-parallel operations. This means that we can modify a b-bit SIMD functional unit so that it has n/2 k-bit sub-functional units or n/4 k-bit sub-functional units. The number of k-bit sub-functional units in a SIMD functional unit is called sub-operation parallelism. We incorporate a sub-operation parallelism optimization algorithm into SIMD functional unit optimization. Our proposed algorithm gradually reduces sub-operation parallelism of a SIMD functional unit while the timing constraint of execution time satisfied. Thereby, we can finally find a processor core with small area under the given timing constraint. We expect that we can obtain processor core configurations of smaller area in the same timing constraint rather than a conventional system. The promising experimental results are also shown.