doi: 10.7873/DATE.2015.0788

Path Selection Based Acceleration of Conditionals in CGRAs

Shri Hari Rajendran Radhikaa, Aviral Shrivastavab and Mahdi Hamzehc

Arizona State University, Tempe, AZ, USA.


Coarse Grain Reconfigurable Arrays (CGRAs) are promising accelerators capable of achieving high performance at low power consumption. While CGRAs can efficiently accelerate loop kernels, accelerating loops with control flow (loops with if-then-else structures) is quite challenging. Existing techniques use predication to handle control flow execution – in which they execute operations from both the paths, but commit only the result of operations from the path taken by branch at run time. However, this results in inefficient resource usage and therefore poor mapping and lower acceleration. The state-of-theart dual issue scheme fetches instructions from both the paths, but executes only the ones from the correct path but this scheme has an overhead in instruction fetch bandwidth. In this paper, we propose a solution in which after resolving the branching condition, we fetch and execute instructions only from the path taken by branch. Experimental results show that our solution achieves 34.6% better performance and 52.1% lower energy consumption on an average compared to state of the art dual issue scheme.

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