[SYCL][L0][CUDA][HIP] L0 plugin enabled for CUDA and HIP backends

[abagusetty]

Is there a need to enable "level_zero" plugin by default (i.e., header, loaders) when building for CUDA and HIP backend.

https://github.com/intel/llvm/blob/sycl/buildbot/configure.py#L53

[AlexeySachkov]

Hi @abagusetty,

I suppose that there could be environment which have devices for both "level_zero" and CUDA backends; or someone may want to build the toolchain in a way that it supports a maximum amount of backends possible.

Therefore, I would be cautious with breaking existing defaults, but I suppose it should be ok to add options like --no-level-zero/--no-opencl to allow disabling some backends which are not needed, but enabled by default.

[abagusetty]

Thanks @AlexeySachkov for confirming. I was able to work with CUDA and HIP plugins by disabling L0 (commenting out this line).

It would be nice to have such option at-least to L0 as you have pointed, since many treat OCL as a fall back backend for any supported cases, it could still be default as it is now. Not a critical request though, as it works with existing setup.

[abagusetty]

Re-opening to make backends mutually exclusive