[CIR][CUDA][NFC] Add NVPTX64 ABI info skeleton

[AdUhTkJm]

Registered ABI Info of NVPTX64 in Clang IR. The bulk of the code is taken from CodeGen/NVPTX.cpp, and I replaced the calls to LLVM with the calls to CIR.

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[bcardosolopes]

Thanks for working on this.

We usually go about developing new features by incrementally introducing only the needed pieces along side testcases that exercise them. Both classifyReturnType and classifyArgumentType should be part of TargetLowering (we don't lower those ABI details directly out of CIRGen).

If you take a closer look at ABIInfo for other targets, you're going to notice they don't do very much at CIRGen stage. It's fine if this PR only introduces a skeleton, but it gotta be reduced to a minimum functionality and be annotated with llvm_unrecheable("not yet implement"), so that you can incrementally add more pieces as you introduce testcases.

[bcardosolopes]

You also need to setup clang-format and format your code according to the LLVM coding guidelines (see the code_formatter failures)

[AdUhTkJm]

Thank you for your explanation. I have reduced the code to a skeleton.
I'm still wondering what test cases should I introduce for this change.

[bcardosolopes]

I'm still wondering what test cases should I introduce for this change.

Ideally this change would have come as part of something you needed to build a testcase, however given this will only introduce skeleton, it's fine to give it a pass!

[AdUhTkJm]

It's done. Sorry for the close and reopen, I accidentally pushed a version identical to this repository onto my fork.

[bcardosolopes]

LGTM, will merge once it passes gh tests

[AdUhTkJm]

Seems content of this PR is already merged, shall I close it?