On the performance of hand vs. automatically optimized numerical codes

In this paper, we compare automatic-optimized codes against hand-optimized codes. The automatic-optimized codes have been generated using our own developed tool that implements compiler techniques proposed in our previous work. Our compiler techniques focus on applying multilevel tiling to non-rectangular loop nests. This type of loop nests are commonly found in linear algebra algorithms, typically used in numerical codes. As hand-optimized codes, we use two different numerical libraries: the BLAS3 library provided by the manufacturers and the RISC-BLAS library proposed in Dayde and Duff (1998). Results will show how compiler technology can make it possible for non-rectangular loop nests to achieve as high performance as hand-optimized codes on modern microprocessors.