一种软件流水的反流水算法

A De-Pipeline Algorithm for Software-Pipeline

软件流水是一种循环程序的优化技术,已经广泛应用于现代优化编译器中.为了充分利用VLIWDSP处理机的指令级并行性,必须使用软件流水技术对DSP程序进行优化.然而,在串行源代码不存在的情况下,对软件流水后的原始代码进行变换、理解、测试和调试,并转换成其他处理机的代码是非常困难的.提出了一种反流水技术,它能够将软件流水后的优化汇编代码反向转换成语义等价的相应代码.通过20个程序的初步实验,验证了所提出的反流水算法的正确性.

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 algorithm which converts the optimized assembly code of a software-pipelined loop back to a semantically equivalent sequential counterpart. Preliminary experiments on 20 programs verify the validity of the proposed de-pipelining algorithm.