Update OCCA Backend

[jeremylt]

Closes #816

• Update for changes in main (rebase or merge?)
• Move files used in JiT to include/ceed/jit-source/occa (I don't fully understand OCCA but I think we can skip this for now?)
• Update tests/junit.py (replaces tests/tap.sh to only run tests for t1*-t3* on OCCA backends
• Update README.md with new OCCA min version and backends
• Update docs/sphinx/source/releasenotes.md
• Update CI
• Odd OCCA_DIR/bin/occa issue

[jeremylt]

$ ENABLE_OPENCL="OFF" ./configure-cmake.sh

followed by

$ cmake --build build --parallel 16

on Noether leads to

[ 64%] Linking CXX executable bin/c/base
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clBuildProgram'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clEnqueueNDRangeKernel'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clSetKernelArg'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clReleaseMemObject'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clFinish'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clEnqueueUnmapMemObject'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clCreateSubBuffer'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clRetainCommandQueue'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clReleaseContext'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clCreateCommandQueueWithProperties'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clReleaseEvent'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clEnqueueWriteBuffer'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clEnqueueCopyBuffer'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clEnqueueReadBuffer'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clEnqueueBarrierWithWaitList'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clGetProgramBuildInfo'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clCreateContext'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clEnqueueMapBuffer'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clGetDeviceIDs'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clGetDeviceInfo'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clReleaseCommandQueue'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clGetPlatformIDs'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clGetPlatformInfo'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clWaitForEvents'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clGetEventProfilingInfo'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clCreateProgramWithBinary'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clGetKernelWorkGroupInfo'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clGetProgramInfo'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clCreateKernel'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clCreateBuffer'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clCreateProgramWithSource'
/usr/bin/ld: ../lib/libocca.so: undefined reference to `clReleaseKernel'
collect2: error: ld returned 1 exit status
gmake[2]: *** [tests/CMakeFiles/bin-c-base.dir/build.make:98: tests/bin/c/base] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:1441: tests/CMakeFiles/bin-c-base.dir/all] Error 2
gmake: *** [Makefile:146: all] Error 2

So it seems that disabling OpenCL is not being respected?

If I don't try to disable OpenCL, I get the warning

CMake Warning at CMakeLists.txt:82 (add_library):
  Cannot generate a safe runtime search path for target libocca because files
  in some directories may conflict with libraries in implicit directories:

    runtime library [libOpenCL.so.1] in /usr/lib/x86_64-linux-gnu may be hidden by files in:
      /opt/intel/oneapi/compiler/latest/linux/lib
      /opt/rocm/lib

[jeremylt]

@kris-rowe, clang-tidy is generating this warning

/var/lib/gitlab-runner/builds/N8GCsqus/0/libceed/occa-1.4.0/install/include/occa/core/kernelArg.hpp:79:5: warning: Call to virtual method 'kernelArg::primitiveConstructor' during construction bypasses virtual dispatch [clang-analyzer-optin.cplusplus.VirtualCall]
    OCCA_GENERIC_CLASS_CONSTRUCTORS(kernelArg);
    ^
/var/lib/gitlab-runner/builds/N8GCsqus/0/libceed/occa-1.4.0/install/include/occa/types/generic.hpp:44:5: note: expanded from macro 'OCCA_GENERIC_CLASS_CONSTRUCTORS'
    primitiveConstructor(arg);                      \

should we be worried?

Unfortunately, this is proving to be very difficult to mark as // NOLINT. It doesn't track easily to single lines and every time one warning goes away, it goes somewhere else.

I'm fine opening an issue to fix these clang-tidy warnings down the road.

[kris-rowe]

I don't think the issues related to these warnings will cause any major problems.

(Adding a linter to the OCCA CI pipeline is on the todo list. I am certain there are lots of things that will be uncovered when we do).

[jeremylt]

Thanks - In that case I think we are ready to merge this.

[jedbrown]

Thanks for this work. Is my understanding correct that this now runs the lower level tests in CI, and passes most higher level tests when using qfunctions (with the syntax workarounds) from a different OCCA branch that will be rebased after this merges? If so, that plan sounds good to me.

[jeremylt]

Is my understanding correct that this now runs the lower level tests in CI,

Yes, we test t0-t3 in CI

and passes most higher level tests when using qfunctions (with the syntax workarounds) from a different OCCA branch that will be rebased after this merges?

That is my understanding as well