[llvm] [BOLT][AArch64] Handle OpNegateRAState to enable optimizing binaries with pac-ret hardening (PR #120064)

[Paschalis Mpeis via llvm-commits]

https://github.com/paschalis-mpeis commented:

Hey Gergely,

Thanks for addressing the review – I think the patch is now mature enough to come out of draft mode soon!

We discussed this offline and it seems a [bolt/docs](https://github.com/llvm/llvm-project/tree/main/bolt/docs) entry explaining this great work and why it matters, along with a 2-3 more tests (eg, code that does actual reordering) would make this complete. Some end-to-end coverage could also come to [bolt-tests](https://github.com/rafaelauler/bolt-tests).

We've seen distros start enabling this feature – the [many failed tests](https://github.com/llvm/llvm-project/pull/136664#issuecomment-2835537481) on #136664 suggest this will only become more important.

On [comment for #120064](https://github.com/llvm/llvm-project/pull/120064#issuecomment-2821064959): thanks for escalating  – are we looking for a possible revert?


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On this review itself, just a couple of nits.

https://github.com/llvm/llvm-project/pull/120064