At least for the GPU case, the ecosystem is slowing moving towards writing generic kernels that can be executed on both the CPU (multithreaded) and the GPU, without doing anything special in the kernel itself, via KernelAbstractions.jl. It's still got a little way to go, but already some larger codes are using it to great effect. Also, as a member of the JuliaGPU group, I know that AMD and Intel GPUs should be supported by KernelAbstractions within the next month or two, so a single generic kernel will be able to run unmodified on all major GPUs.