Abstract: There are a large number of loops which contain few unvectorizable statements and many vectorizable statements.Loop distribution separates these specific statements into different loops,and then partial vectorization can be achieved.Currently,the mainstream optimizing compiler just support loop distribution which is simple and aggressive,resulting in large loop overhead and bad reuse of register and cache.To solve these problems,a method of loop distribution and aggregation for partial vectorization was proposed.Firstly,two key issues were analyzed in loop distribution,which are grouping of statements and execution order of distributed loops.Secondly,a modified topological sorting method was presented to achieve better loop aggregation,which reduces the loop overhead.Finally,we evaluated the proposed method in the experimental section.The experimental results show that the proposed method can produce correct SIMD code,and can significantly improve the efficiency of implementation program.

Key words: Prtial vectorization,Loop distribution,Loop aggregation,Aggregation graph