[llvm] [llvm] Fix behavior of llvm.objectsize in presence of negative / large offset (PR #115504)

[Harald van Dijk via llvm-commits]

hvdijk wrote:

> @hvdijk : Are you fine with me landing this as part of https://github.com/llvm/llvm-project/pull/115522 ?

I'm fine with combining the two PRs, but make sure that the approvals in the other PR cover everything. When I asked "To avoid confusion: this includes the changes from https://github.com/llvm/llvm-project/pull/115504 unmodified, and only the additional commit on top of that should be reviewed here?", you gave a thumbs up to that, and I think it's reasonable to assume other people who approve your other PR will also read that and only look at the most recent commit.

I still think that this PR, even if it results in improved results in some cases, will result in incorrect results in other cases, so personally, I do not think it should be merged as is, but if there is agreement with other people and those possible incorrect results will soon be addressed in a followup PR, I'm also not going to stand in the way.

https://github.com/llvm/llvm-project/pull/115504