[llvm] Verify threadlocal_address constraints (PR #87841)

[Nikita Popov via llvm-commits]

https://github.com/nikic approved this pull request.

LGTM. I am a bit concerned that we're going to violate these rules in some transforms (e.g. by creating threadlocal.address of a phi or select), though at least from some cursory testing we seem to already avoid converting intrinsics with constants args into non-constants. I guess we can try this and see whether anything falls out.

https://github.com/llvm/llvm-project/pull/87841