[SYCL] Allow default selected GPU to be from any available platform

[steffenlarsen]

Removes the assumption that level-zero is available and the default on the system, allowing the default GPU to be from either the OpenCL backend, the CUDA backend, or the L0 backend.

[steffenlarsen]

The changes clang-format suggests will invalidate the test.

[smaslov-intel]

I am afraid this test doesn't actually check anything then. What are the SYCL RT changes that change the default? Should we somehow really test that if multiple platforms are discovered then something specific is selected?

[steffenlarsen]

On my system sycl-ls reports the following

0. CPU : Intel(R) OpenCL 2.1 [2020.9.1.0.18]
1. GPU : NVIDIA CUDA BACKEND 0.0 [CUDA 11.0]
2. HOST: SYCL host platform 1.2 [1.2]

so the test - as is - fails.

After these changes I suppose the only thing this test checks is that the default is a GPU that belongs to one of the DPC++ backends and not something bogus or unexpected. I agree, it is not a lot, but as is this test depends on it being on a system that has sycl-ls report a L0 GPU.

[smaslov-intel]

the test - as is - fails.

Understood. Let's then create multiple tests.
One that is checking that Level-Zero is the default when Level-Zero is available. For that you'd decorate it with:

// REQUIRES: level_zero

The other (new one) is doing what you did.

[steffenlarsen]

Good call. I have done as suggested. Would you like me to rename sycl-ls-gpu-default.cpp to something that makes the distinction more clear? (sycl-ls-gpu-default-level-zero.cpp for example.)

[smaslov-intel]

Would you like me to rename sycl-ls-gpu-default.cpp to something that makes the distinction more clear? (sycl-ls-gpu-default-level-zero.cpp for example.)

Yes, I think this would be fair.

[smaslov-intel]

LGTM

[vladimirlaz]

@steffenlarsen could you please fix clang-format issues?

[steffenlarsen]

@steffenlarsen could you please fix clang-format issues?

I would like to, but I don't think it's possible without invalidating the test. Clang-format wants the check to be in two lines, but from my tests I have concluded that it results in it ignoring the second line.

[vladimirlaz]

@steffenlarsen could you please fix clang-format issues?

I would like to, but I don't think it's possible without invalidating the test. Clang-format wants the check to be in two lines, but from my tests I have concluded that it results in it ignoring the second line.

You can try approach used in https://github.com/intel/llvm-test-suite/blob/intel/SYCL/Plugin/interop-level-zero.cpp#L8