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Elliot Gorokhovsky
Elliot Gorokhovsky

Reputation: 3762

Is it possible to write OpenCL kernels in C++ rather than C?

I understand there's an openCL C++ API, but I'm having trouble compiling my kernels... do the kernels have to be written in C? And then it's just the host code that's allowed to be written in C++? Or is there some way to write the kernels in C++ that I'm not finding? Specifically, I'm trying to compile my kernels using pyopencl, and it seems to be failing because it's compiling them as C code.

Upvotes: 7

Views: 6931

Answers (4)

Mats Petersson
Mats Petersson

Reputation: 129364

This is an old question, and the work to "solve" it has been ongoing for some time...

There is a community-driven C++ for OpenCL kernel language that is implemented by clang Clang C++ for OpenCL and there is a Khronos extension cl_ext_cxx_for_opencl that adds an online compilation of this language to OpenCL drivers too. Arm has just announced the support for this extension. Although it is also possible to compile kernels in this language offline using upstream tools into machine binary, SPIR-V, or any other IR and then load the precompiled code in OpenCL drivers without any extension.

Upvotes: 1

My Name
My Name

Reputation: 166

I would add SYCL on ComputeCpp from Codeplay. They have been very active at IWOCL.org promoting the use of single source C++ host and kernel code. SYCL has OpenCL execution model "under the hood". https://en.wikipedia.org/wiki/SYCL. Though Wikipedia has this statement about SYCL: "The open standards SYCL and OpenCL are similar to vendor-specific CUDA from Nvidia." Which cannot be any further from the intent of portable code (not performance portable) of SYCL and OpenCL.

You can find information, news, blogs, videos and resourcs on SYCL on the sycl.tech website.

Upvotes: 4

helmingstay
helmingstay

Reputation: 276

For reference, there's also Boost.Compute. It doesn't help you with pyopencl, but it addresses many of the issues that pyopencl does, and has some metaprogramming magic that facilitates writing OpenCL kernels in C++.

This SO question (referenced in the Boost.Compute FAQ) also contains a nice discussion of some of the relevant design constraints that OpenCL poses to devs.

Upvotes: 1

doqtor
doqtor

Reputation: 8484

OpenCL C is a subset of C99.

There is also OpenCL C++ (OpenCL 2.1 and OpenCL 2.2 specs) which is a subset of C++14 but it's not implemented by any vendor yet (OpenCL 2.1 partially implemented by Intel but not C++ kernels).

Host code can be written in C,C++,python, etc.

In short you can read about OpenCL on wikipedia. There is a description about each OpenCL version. In pyopencl you can use OpenCL1.2 (as far as I'm aware there isn't support for OpenCL2.0 yet). More details about OpenCL on Khronos website.

Upvotes: 10

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