What's possible with OpenCL 2.0 today?
AMDGPU-PRO is the closed-source implementation of OpenCL 2.x for AMD. It only targets AMD GPU. AMD used to provided a CPU target, but it is OpenCL 1.2 only.
rocm is the heterogeneous computing effort of AMD, and is open-source. It also has an OpenCL 2.x target for GPU only. It should be noted that there are many restriction on the supported hardward (e.g., Raven ridge APU, aka Ryzen APU, are _not_ supported).
The debugger is CodeXL (?). It does not seem to support rocm debugging in the latest 2.5 version.
rocm also has both a llvm-based and a gdb-based debugger, but both are old compared to the latest rocm 1.7 release.
Intel OpenCL SDK is the closed-source implementation of OpenCL 2.x for Intel. It targets both CPU and GPU in OpenCL 2.x.
Like AMD, Intel modified gdb for GPU debugging.
There is a beta support for OpenCL 2.x in the lastest Cuda SDK. No CPU target.
Oclgrind only supports OpenCL 1.2.
pocl supports CPU and GPU targets in OpenCL 2.x.