[llvm] [AArch64] Convert CLS intrinsics to use ISD::CTLS (PR #178885)

[Hamza Hassanain via llvm-commits]

HamzaHassanain wrote:

@topperc 

I’m not sure how to exercise these new paths in tests.

As far as I understand

 `expandCTLS` only runs if a CTLS node exists on a type marked Expand, but we don’t currently generate CTLS in IR (no `llvm.ctls`), and `DAGCombiner` only forms CTLS when it’s Legal/Custom.

`ExpandIntRes_CTLS`  likewise needs CTLS on an illegal type (e.g., i128), which we don’t produce today.

What should I do? And How can I test those?

https://github.com/llvm/llvm-project/pull/178885