CL_TARGET_OPENCL_VERSION is not defined. Defaulting to 220 (OpenCL 2.2)

[fwyzard]

This pops up multiple times during a build and when running tests.

Any objections to set CL_TARGET_OPENCL_VERSION to some value to silence it ?

I guess some sensible values could be

• 120 since SYCL should require only OpenCL 1.2
• 210 since AOT requires OpenCL 2.1
• 220 since it's default and is being used anyway
• 300 just to give it a try ...

[fwyzard]

In fact, I see that CL_TARGET_OPENCL_VERSION is defined to 220 in

llvm/sycl/include/CL/sycl/detail/common.hpp

Lines 14 to 16 in bb73d92

	// Suppress a compiler warning about undefined CL_TARGET_OPENCL_VERSION
	// Khronos ICD supports only latest OpenCL version
	#define CL_TARGET_OPENCL_VERSION 220

However, there are other places that #include <CL/cl.h> or #include <CL/opencl.h>:

opencl-aot/include/utils.h
opencl-aot/source/main.cpp
sycl/include/CL/cl_usm_ext.h
sycl/include/CL/sycl/detail/aligned_allocator.hpp
sycl/include/CL/sycl/detail/buffer_impl.hpp
sycl/include/CL/sycl/detail/memory_manager.hpp
sycl/include/CL/sycl/detail/memory_manager.hpp
sycl/include/CL/sycl/detail/pi.h
sycl/plugins/opencl/pi_opencl.cpp

How about adding the flag directly to the CMakeFile.txt instead of the various source files ?

[bader]

I guess some sensible values could be

• 120 since SYCL should require only OpenCL 1.2
• 210 since AOT requires OpenCL 2.1
• 220 since it's default and is being used anyway
• 300 just to give it a try ...

@fwyzard, just out of curiosity, did you try these options? IIRC, there were some issues with using values other than 220, but it was quite a long time ago, so they might be fixed already.

[fwyzard]

210 needs a minor fix, which is part of #1608, just in case.

I didn't try anything older, once I read that AOT requires OpenCL 2.1 or later.

[bader]

I didn't try anything older, once I read that AOT requires OpenCL 2.1 or later.

I can't anything like this. Where did you find this requirement?

[fwyzard]

https://github.com/intel/llvm/blob/sycl/opencl-aot/README.md says

Prerequisites

To use opencl-aot tool, you must have:

• OpenCL runtime installed for the target device (see Install low level runtime)
• OpenCL ICD Loader installed with support of OpenCL 2.1 or higher

so I assumed there is no point in building it with headers that don't have OpenCL 2.1.

[bader]

Thank you.
opencl-aot tool uses OpenCL API to compile device code in SPIR-V format to the executable format.
Technically it can done using cl_khr_il_program extension for OpenCL 1.x/2.0 in addition to using standard OpenCL 2.1 API.

Another note: I'm not sure if it's possible to build OpenCL ICD Loader with API version support < 2.2. Last time I checked the loader library didn't build if CL_TARGET_OPENCL_VERSION is < 220.

[fwyzard]

I think it builds with 210 - at least, I could build the whole make sycl-toolchain with #1608 but using add_definitions(-DCL_TARGET_OPENCL_VERSION=210).

Anyway, I don't see any reasons for not using 220.

[bader]

I think it builds with 210 - at least, I could build the whole make sycl-toolchain with #1608 but using add_definitions(-DCL_TARGET_OPENCL_VERSION=210).

Your change affects only opencl-aot tool and sycl library, but not ICD Loader.

Anyway, I don't see any reasons for not using 220.

Me neither.

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[bader]

Fixed by #1608.