Symbolic expression analysis for compiled communication

Enabling circuit switching in multiprocessor systems has the potential to achieve more efficient communication with lower cost compared to packet/wormhole switching. However, in order to accomplish this efficiently, assistance from the compiler is required to reveal the communication pattern in the parallel application. In this paper we present symbolic expression analysis techniques in a MPI parallel compiler. Symbolic expression analysis allows the identification and representation of the communication pattern and also assists in the determination of communication phases in MPI parallel applications at compile-time. We demonstrate that using the compiler analysis based on symbolic expression analysis to determine the communication pattern and phases provides an average of 2.6 times improvement in message delay over a threshold-based runtime system for our benchmarks with a maximum improvement of 9.7 times.