[llvm] [GlobalIsel][AArch64] legalize ptr add (PR #89218)

[Dhruv Chawla via llvm-commits]

dc03-work wrote:

> The new error after `moreElementsToNextPow2` is:
> 
> ```
> unable to legalize instruction: %res:_(<3 x p0>) = G_PTR_ADD %ptr:_, %add:_(<3 x s64>) (in function: test_ptr_add_vec_3xp0)
> ```

Do you have a more detailed log? I guess scalarization can be done for odd-sized vectors, but having moreElements support would be a better solution.

https://github.com/llvm/llvm-project/pull/89218