[llvm] Revert "Reland "[CodeGen] Use byte offsets and ptradd in ShadowStackGCLowering" (#197436)" (PR #222223)

[Jameson Nash via llvm-commits]

vtjnash wrote:

Because you need to justify your revert with more than just saying you don't like it. It isn't objectively wrong if all the tests and documentation state that there isn't anything wrong with it or we wouldn't get anywhere. Most of the intrinsic functions can be abused for some undocumented behavior of some sort, but that doesn't mean you get to assume that undefined behavior is guaranteed to work forever (or segfault forever, I guess -- I'm still confused about why you showed this that before this revert you get compiler segfaults at O1 as evidence it worked).

Make a PR for what you actually want this to do, and I'm happy to support you.

https://github.com/llvm/llvm-project/pull/222223