[llvm] [BOLT][AArch64] Support for pointer authentication (v2) (PR #120064)

[via llvm-commits]

Heart-tide wrote:

Hi @bgergely0 . Thank you for your PR! It works well in most scenarios. However, while testing on `vmlinux`, I occasionally encountered a segmentation fault at `InsertNegateRAStatePass.cpp:81`.

Observations:
- The crash occurs at `PrevInst = Inst` after `BF.addCFIInstruction()` is called.
- When I modified the code to use a local copy of `*It` (instead of a reference `MCInst& Inst`), the crash no longer reproduced.

Hypothesis:
The `vector::insert` operation within `addCFIInstruction()` may invalidate existing iterators/references (per C++ iterator invalidation rules). This could turn `Inst` into a dangling reference if the vector reallocates, leading to UB when accessed later.

Since the issue is non-deterministic (depends on reallocation), it might explain the intermittent crashes. Would you please review the iterator/reference handling around the CFI insertion point? Thank you for your time!

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