Loop-nest Auto-vectorization Method Based on Benefit Analysis.

The SIMD (Single Instruction Multiple Data) extension component has been widely used in modern processors to improve the execution efficiency of the program. The mainstream compilers (such as GCC, ICC, OPEN64, etc.) have supported the SIMD automatic vectorization. Most current compilers can only vectorize the innermost layer of the loop, but this way often does not get the optimal performance promotion. Aiming at this kind of problem and combining with the processor architecture, a loop-nest vectorization method based on the benefit analysis model is proposed and implemented in the GCC compiler. This method can analyze different loop-nest vectorization schemes effectively and choose the most profitable one as the final optimization scheme. This article first reviewed the researches about loop-nest vectorization, then introduces this new code generation method for loop-nest vectorization. Finally, we use several common application examples for experiment. The experimental results show that the results of the benefit model are similar to the actual test results, and accordingly increase the efficiency for loop-nest vectorization.