[clang] [CIR][AArch64] Lower vfma lane builtins (PR #188190)

[Andrzej Warzyński via cfe-commits]

https://github.com/banach-space commented:

Thanks! I have a high-level ask - could you split this PR into multiple PRs?

Basically, this is implementing quite a few variants in one PR:
* `BI__builtin_neon_vfmaq_v`
* `BI__builtin_neon_vfmaq_lane_v`
* `BI__builtin_neon_vfma_laneq_v`
* `BI__builtin_neon_vfmaq_laneq_v`
* `BI__builtin_neon_vfmad_laneq_f64`

The implementations are different, some tests are missing (e.g. for `BI__builtin_neon_vfmaq_v`) and the output generated _with_ and _without_ `-fclangir` do not match. This will require taking a closer look, hence kind request to split this. Could you start with `BI__builtin_neon_vfmaq_v`?

Thanks for working on this! I am leaving more comments inline.

https://github.com/llvm/llvm-project/pull/188190