Compiling control-intensive loops for CGRAs with state-based full predication

Abstract

Predication is an essential technique to accelerate kernels with control flow on CGRAs. While state-based full predication (SFP) can remove wasteful power consumption on issuing/decoding instructions from conventional full predication, generating code for SFP is challenging for general CGRAs, especially when there are multiple conditionals to be handled due to exploiting data level parallelism. In this paper, we present a novel compiler framework addressing central issues such as how to express the parallelism between multiple conditionals, and how to allocate resources to them to maximize the parallelism. In particular, by separating the handling of control flow and data flow, our framework can be integrated with conventional mapping algorithms for mapping data flow. Experimental results demonstrate that our framework can find and exploit parallelism between multiple conditionals, thereby leading to 2.21 times higher performance on average than a naive approach.