AdaptiveCpp installation instructions for SPIR-V/OpenCL

You will need an OpenCL implementation, and the OpenCL icd loader. The OpenCL library can be specified using cmake -DOpenCL_LIBRARY=/path/to/libOpenCL.so.

In order to generate correct code, AdaptiveCpp needs to apply a patch to the Khronos llvm-spirv translator. You must have the patch command installed and available when running the AdaptiveCpp cmake configuration. If you have run cmake without the patch command available, please clean your build directory before trying again.

The OpenCL backend can be enabled using cmake -DWITH_OPENCL_BACKEND=ON when building AdaptiveCpp. In order to run code successfully on an OpenCL device, it must support SPIR-V ingestion and the Intel USM (unified shared memory) extension. In a degraded mode, devices supporting OpenCL fine-grained system SVM (shared virtual memory) may work as well.