Abstract: Software Pipelining（SWP） is the scheduling technology for the loop in the compiling back-end optimization. In the process of SWP optimization, the dependency circle is an important factor to affect the optimization of SWP. Based on the traditional modulo scheduling, a new SWP optimization algorithm is proposed to deal with the problem of SWP failure caused by the dependency circle. It does analysis of the dependency circle for loop, splits the reduced register into several counterpart duplicates and makes the loop with reduced variable pipelining favorably. Through the classical algorithm testing, experimental results show that the framework can make more loops pipelining successfully and improve performance at 58% least.

Key words: Software Pipelining（SWP）, dependency circle, modulo scheduling, loop, optimization

摘要： 软件流水是编译后端优化中针对循环的调度技术，在软件流水优化过程中，依赖环是影响软件流水优化的重要因素。针对循环体中依赖环导致软件流水失败的问题，通过对循环中的依赖环进行分析处理，基于传统的模调度框架，提出了改进的软件流水优化算法，对于造成依赖环的寄存器引入多个分量，实现了对含有归约变量循环的流水。通过典型的算法测试，实验结果表明，该框架能够使得更多类型的循环流水成功，对于循环核心性能提升至少58%。

关键词: 软件流水, 依赖环, 模调度, 循环, 优化