Add oneAPI DPC++ ESIMD extention as a new backend for T2S on GPU

[tanzelin430]

No description provided.

[ronghongbo]

Zelin, thanks for the great efforts. Overall, it looks good. There are many minor places to fix, though:

1. OneAPI and DPC: we have both terms used in many places due to historical reasons. You may help clean up this mess. I would suggest you to change them into something like "DPC_GPU" and "DPC_FPGA", or "OneAPI_GPU" and "OneAPI_FPGA". But you can leave this as the next step, though.
2. Halide/performance: what is the purpose of this directory? remove it if not needed
3. Halide/preprocessor: same question as above
4. Codegen_GPU_Host.cpp: 120: I would suggest to add "CM", "DPC/OneAPI_FPGA", "DPC/OneAPI_GPU" features to Halide/src/Target.h and check against them.
5. Halide/src/CodeGen_LLVM.cpp: The debugging line is useless now after you made things work
6. Halide/src/Module.h: 43: again, we have the mix-use of "DPC" and "OneAPI". They are the same and we should keep only one of them.
7. Target.cpp: 666 and 669: Add something like WITH_DPC in Halide/Makefile, and change these lines correspondingly.
8. Target.cpp: 690-694: if the else statement is not useful any more, remove it.
9. Pipeline.cpp: make { after a statement so that the coding style is consistent with the rest of the system
10. install-tool.sh: 24: can a common user uses "apt install"? I guess users do not necessarily have the root privilege to do that. Since python is popular and used everywhere, I would suggest to not install python. Instead, in README, just list python (2x or 3x) as a prerequisite.
11. setenv.sh: keep the useful changes, and remove the dead ones.
12. preprocessor: we need to move it to t2s/src, and also clean up the file names (like post.t2s.......) Currently Abe makes file names too long). We should make the file names consistent with the workflow.png shows
13. preprocessor/sample: (1) the several samples have many generated files. They should not be checked in. (2) oneapi-target-4-parameters.h should be renamed into const-parameters.h? (3) HalideBuffer., buffer_t., HalideRuntime., runtime_internal. should all be removed. They can be found from Halide/src, Halide/src/runtime, etc. So in a command line, you can use "-I ..." to set include paths to include .h files, or add path_to_a_cpp_file/something.cpp, to make things work without such copies. (3) pipe_array* files are copied from https://oneapi.team/tattle/oneAPI-samples/-/tree/9d8b94a38f2a98042cf933adfb91ec1da3d5ad51/DirectProgramming/DPC++FPGA/Tutorials/DesignPatterns/pipe_array/src. Please add some command lines in install-tool.sh to achieve this effect, instead of hard copies. (4) Sample03/perf.cpp: is it still useful? (5) util.h can be included from t2s/tests/correctness/util. No need for another copy.
14. tests/performance/capsule.cpp: it does not seem you have made any real change. Recover the original files if the only difference is format. I saw some other files having similar issues. You would like to minimize the number of files in your check in
15. performance/capsule/const-parameters.h: why changing the parameters? That would invalidate the performance numbers we report.
16. performance/gemm/const-parameters.h: same question as above
17. performance/gemm/gemm-run-gpu-oneapi.cpp: is this file useful?

Please clean up the files based on the feedback, and let me take a look again. Thanks!

[ronghongbo]

Xiaochen has merged your changes into his fork, and will push to main repo in future together with his changes.