5. The CPU Platform

CpuPlatform is a subclass of ReferencePlatform. It provides optimized versions of a small number of kernels, while using the reference implementations for all the others. Any kernel implementation written for the reference Platform will work equally well with the CPU platform. Of course, if that kernel happens to be a performance bottleneck, you will probably want to write an optimized version of it. But many kernels have negligible effect on performance, and for these you can just use the same implementation for both platforms.

If you choose to do that, you can easily support both platforms with a single plugin library. Just implement registerKernelFactories() like this:

extern "C" void registerKernelFactories() {
    for (int i = 0; i < Platform::getNumPlatforms(); i++) {
        Platform& platform = Platform::getPlatform(i);
        if (dynamic_cast<ReferencePlatform*>(&platform) != NULL) {
            // Create and register your KernelFactory.
        }
    }
}

The loop identifies every ReferencePlatform, either an instance of the base class or of a subclass, and registers a KernelFactory for every one.