[llvm-branch-commits] [llvm] [AArch64][PAC] Introduce AArch64::PAC pseudo instruction (PR #146488)

[Peter Collingbourne via llvm-branch-commits]

pcc wrote:

I think this should be opt-in behavior. It might be useful if the goal is to protect the stack, but in cases where the goal is to only protect the heap due to the high cost of protecting the stack, this change would only add overhead.

If you are deploying a comprehensive stack protection, I think something like Darwin's x16/x17 protection would be necessary, so maybe we can use isX16X17Safer() as the control for whether to turn this on?

https://github.com/llvm/llvm-project/pull/146488