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

[via llvm-commits]

isuckatcs wrote:

> the LangRef requires an update to argue what behavior you are intending the intrinsic to have.

I agree with this, but it is unrelated to this revert.

We have 2 separate issues:
1. a merged commit causes regression
2. the LangRef is outdated since 2010

This revert solves 1. It restores the behavior that we had before. It is irrelevant whether that behavior was right or wrong. That is a concern of a separate patch to address it.

The only concern of this patch is to undo an objectively proven to be incorrect commit. I don't see any objective blockers to this revert.

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