  We present an efficient approach for writing architecture-agnostic parallel
high-performance stencil computations in Julia, which is instantiated in the
package ParallelStencil.jl. Powerful metaprogramming, costless abstractions and
multiple dispatch enable writing a single code that is suitable for both
productive prototyping on a single CPU thread and production runs on multi-GPU
or CPU workstations or supercomputers. We demonstrate performance close to the
theoretical upper bound on GPUs for a 3-D heat diffusion solver, which is a
massive improvement over reachable performance with CUDA.jl Array programming.
