You mean for CPUs? Check out ISPC, it's essentially a lightweight data-parallel C for CPUs (that has been ported to Intel GPUs too!), and I think also works fine on even some non-x86 architectures. I'm not sure if there's any mature CPU OpenCL runtimes.
Intel also still supports OpenCL as a first-class target on their GPUs, which is more than I can say for Nvidia or AMD.