[clang] [llvm] [AArch64] Implement the atomic store with hint intrinsic (PR #198316)

[Kerry McLaughlin via llvm-commits]

kmclaughlin-arm wrote:

> Can this not use the recently introduced `!mem.cache_hint` metadata? https://llvm.org/docs/LangRef.html#mem-cache-hint-metadata
> 
> As far as I understand it, the hint here is specifically a cache hint. (It would be great if the PR description explained what this actually does, so one doesn't have to go chasing through ARM manuals.)

Hi @nikic,
I have rewritten this PR to use the `!mem.cache_hint` metadata as suggested & updated the commit message to try and provide more context. Could you please take a look to make sure that I have made the changes that you requested on an earlier commit, as merging is currently blocked? Thanks!

https://github.com/llvm/llvm-project/pull/198316