De-pipeline a software-pipelined loop

1 Dept. of Computer Science, The William Paterson University of New Jersey, Wayne, NJ 07470, USA 2 Wireless Speech and Data Processing, Nortel Networks, Montreal, QC, Canada, H3E 1H6 Abstract Software pipelining is a loop optimization technique that has been widely implemented in modern optimizing compilers. In order to fully utilize the instruction level parallelism of the recent VLIW DSP processors, DSP programs have to be optimized by software pipelining. However, because of the transformation of the original sequential code, a software-pipelined loop is often difficult to understand, test, and debug. It is also very difficult to reuse and port a software-pipelined loop to other processors especially when the original sequential code is unavailable. In this paper we propose a de-pipelining technique, which converts the optimized assembly code of a softwarepipelined loop back to a semantically equivalent sequential counterpart. Preliminary experiments on 20 assembly programs verifies the validity of the proposed depipelining algorithm.