Detection and Propagation of Periodic Constant
Binyu Zang · Journal of Chinese Computer Systems · 2006
Periodic constant, whose value appears periodically within a loop, brings about unnecessary control dependency as well as loop carried and loop independent data dependency. This paper introduces the concept of periodic constant and the process of transforming induction scalar to difference equation. Moreover, by applying some algebraic knowledge, this paper proposes and proves a complete and necessary condition of the existence of periodic constant. Based on this condition, this paper advances an intrinsic algorithm which detects and propagates the periodic constant and measures its cycle. An average acceleration of more than 10% is obtained when this algorithm is applied to the ADPCM decoder and encoder.