Efficient Stencil Computation with Temporal Blocking by Halide DSL

The stencil computation is a memory centric computation, where memory access becomes a bottleneck. Therefore locality improvement method like temporal blocking is essential to improve the speed. Introducing temporal blocking, however, introduces heavy programming costs. This paper proposes a methodology to implement efficient stencil software with temporal blocking easier using the domainspecific language Halide. Generally, boundary conditions, such as Neumann and Dirichlet boundary conditions, are needed in stencil computations. Also user-defined boundary computations may be needed in general fluid dynamics applications. We indicate a pitfall in combining temporal blocking and boundary conditions on Halide and show a solution to improve performance. We also apply our methodology to the II otspot3 benchmark from Rodinia benchmark suite and demonstrate 3.5 to 5.0 times performance improvement over the original OpenNIP implementation.