Level zero codegen

[diptorupd]

The PR adds an optional feature to enable Level Zero program creation from SPIR-V in dpctl.

• The feature is enabled for Linux for the time being.
• When using this feature level-zero-dev headers should be installed.
• Windows support is not enabled at this point.

[diptorupd]

@PokhodenkoSA @oleksandr-pavlyk I can get the C API to work, but I need help with getting Python to find the level zero loader library:

1. How should the level-zero loader libraray be located? On my local system it is installed under /usr/lib/x86_64-linux-gnu/. However, Python is unaware of the library and I get this error:

ImportError: Failed to import test module: dpctl
Traceback (most recent call last):
  File "/home/diptorupd/.conda/envs/dpctl-devel/lib/python3.8/unittest/loader.py", line 154, in loadTestsFromName
    module = __import__(module_name)
  File "/home/diptorupd/Desktop/devel/dpctl/dpctl/__init__.py", line 38, in <module>
    from dpctl._sycl_core import *
ImportError: /home/diptorupd/Desktop/devel/dpctl/dpctl/libDPCTLSyclInterface.so: undefined symbol: zeModuleCreate

2. The Linux CI server needs the level-zero headers (level-zero-dev) to be installed. The driver should already be available.

Ideally we should be packaging the libze_loader as a conda package. Surprisingly, the intel-compute-runtime conda package does not include the level zero library.

Once these two changes are done, we should be good to go.

[oleksandr-pavlyk]

Level-zero libraries and level-zero include headers must be made available to Python as conda package, if ze_loaded is directly linked to DPCTLSyclInterface. oneDAL does not link directly, but likely uses dlopen :

(base) [13:31:57 ansatnuc04 ~]$ grep ze_loader /localdisk/intel/oneapi/dal/latest/lib/intel64/*.so
Binary file /localdisk/intel/oneapi/dal/latest/lib/intel64/libonedal_dpc.so matches

(base) [13:40:02 ansatnuc04 ~]$ ldd /localdisk/intel/oneapi/dal/latest/lib/intel64/*.so | grep 'ze_loader' | wc
      0       0       0

[oleksandr-pavlyk]

oneDAL's solution: https://github.com/oneapi-src/oneDAL/blob/1e6f13f10d14a117e235aaf6217f3c4a65469d4a/cpp/daal/include/services/internal/sycl/level_zero_module_sycl.h#L82

[diptorupd]

oneDAL's solution: https://github.com/oneapi-src/oneDAL/blob/1e6f13f10d14a117e235aaf6217f3c4a65469d4a/cpp/daal/include/services/internal/sycl/level_zero_module_sycl.h#L82

The reason this works is that they include the headers almost verbatim inside oneDAL https://github.com/oneapi-src/oneDAL/blob/1e6f13f10d14a117e235aaf6217f3c4a65469d4a/cpp/daal/include/services/internal/sycl/level_zero_common.h.

We need to know level zero types to create the function pointers as is done here:
https://github.com/oneapi-src/oneDAL/blob/1e6f13f10d14a117e235aaf6217f3c4a65469d4a/cpp/daal/include/services/internal/sycl/level_zero_common.h

Is this the route we want to go? If we want level zero support on Windows, at this point there is no real alternatives as the headers are not available on Windows.

[diptorupd]

Merging since CI passes and no objections :)