[llvm] GlobalsModRef, ValueTracking: Look through threadlocal.address intrinsic (PR #88418)

[Eli Friedman via llvm-commits]

https://github.com/efriedma-quic approved this pull request.

LGTM

Making ValueTracking look though the intirnisc should be fine, I think?  Certain IPO passes might need to be a little careful with how they deal with an identified thread-local, but that was true even before threadlocal.address was a thing.

GlobalsModRef seems fine; it never returns MustAlias, so approximating the thread-locals of all threads as a single "global" should be fine.

https://github.com/llvm/llvm-project/pull/88418