[llvm] [AArch64] Use a load instead of a store for inline stack probes (PR #170855)

[Sander de Smalen via llvm-commits]

https://github.com/sdesmalen-arm approved this pull request.

> > Frequently, when big buffers are put on the stack we end up with multiple virtual pages COW-mapped to single physical zero page. Stack probes would unnecessarily trigger a COW on such pages. Avoid this by using loads into the `XZR`.
> 
> Done. Thanks!

nit: I see you've updated the message of the commit, but not the description of the pull-request (which is what will eventually be used when merging the PR). Can you update that, and also expand 'COW' to Copy-On-Write?

Otherwise LGTM

https://github.com/llvm/llvm-project/pull/170855