[compiler-rt] [libcxx] [libcxxabi] [libunwind] [runtimes][PAC] Harden unwinding when possible (PR #143230)

[Daniil Kovalev via llvm-commits]

kovdan01 wrote:

@ojhunt Thanks! So could you please adopt the code snippet from my previous comment to make things explicitly unsupported for Linux?

And also I kindly ask you to fix p.4 from https://github.com/llvm/llvm-project/pull/143230#issuecomment-3249013139 (we've already discussed that in Discord). Please let me know if you need any help.

A couple of things are on my side:

1. Compile a local pac-ret-enabled toolchain. This would allow you to fix p.3 from the same comment. I'll let you know when it's ready.
2. Look through other comments in this PR (they have lower priority since they are not related to any runtime/compile-time failures). I'll highlight the ones which I think are worth fixing in scope of this PR (if any).

Please let me know if I've missed smth or if you have any objections on this plan.


https://github.com/llvm/llvm-project/pull/143230