Improving the Performance of GCC by Exploiting IA-64 Architectural Features

The IA-64 architecture provides a rich set of features to aid the compiler in exploiting instruction-level parallelism to achieve high performance. Currently, GCC is a widely used open-source compiler for IA-64, but its performance, especially its floating-point performance, is poor compared to that of commercial compilers because it has not fully utilized IA-64 architectural features. Since late 2003 we have been working on improving the performance of GCC on IA-64. This paper reports four improvements on enhancing its floatingpoint performance, namely alias analysis for FORTRAN (its part for COMMON variables already committed in GCC 4.0.0), general induction variable optimization, loop unrolling and prefetching arrays in loops. These improvements have significantly improved the floating-point performance of GCC on IA-64 as extensively validated using SPECfp2000 and NAS benchmarks.