[llvm] [AArch64] Handle inttoptr+add+ptrtoint pattern in lowerConstantPtrAuth (PR #189474)

[Oskar Wirga via llvm-commits]

oskarwirga wrote:

> How does this work in Swift then? Is there downstream change? Can you point to it?

Swift's fork does not contain this fix. I encountered this when `lowerConstantPtrAuth` received a `ConstantPtrAuth` with a null base and with an `inttoptr(add(ptrtoint))` pattern. The test case in `ptrauth-reloc.ll` is derived from the crashing IR.

I've updated the PR description's wording to be more precise.

https://github.com/llvm/llvm-project/pull/189474