[clang] [OpenMP][wip] Rework 'containing struct'/overlapped mapping handling (PR #153672)

[Abhinav Gaba via cfe-commits]

abhinavgaba wrote:

Thanks for the PR. I haven't been able to look at how it can work along with the pointer-attachment rework.

Please look at https://github.com/llvm/llvm-project/pull/153683/ when you get a chance. The updates tests have comments showing the current maps being emitted. In that, I'm trying to group maps based on the attach-exprs. It works for most cases, but I am yet to get down to some of the failing tests with use_device_ptr/addr, and target_update.

That change is relying on comparing the attach-ptr exprs, so for now, for `int **pp;` `pp[10][0]` and `(*(p + 10)[0]` have different base-ptrs, since *(p + 10) and `p[10]` are different Exprs, even if they evaluate to the same address.

https://github.com/llvm/llvm-project/pull/153672