Compiler-Directed ILP Extraction for Clustered VLIW/EPIC Machines
Satish Pillai, Margarida F. Jacome · Kluwer Academic Publishers eBooks · 2005
Compiler-directed ILP extraction techniques are critical to effectively exploiting the significant processing capacity of contemporaneous VLIW/EPIC machines. In this paper we propose a novel algorithm for ILP extraction targeting clustered EPIC machines that integrates three powerful techniques: predication, speculation and modulo scheduling. In addition, our framework schedules and binds operations to clusters, generating actual VLIW code. A key innovation in our approach is the ability to perform resource constrained speculation in the context of a complex (phased) optimization process. Specifically, in order to enable maximum utilization of the resources of the clustered processor, and thus maximize performance, our algorithm judiciously speculates operations on the predicated modulo scheduled loop body using a set of effective load based metrics. Our experimental results show that by jointly considering different extraction techniques in a resource aware context, the proposed algorithm can take maximum advantage of the resources available on the clustered machine, aggressively improving the initiation interval of time critical loops.