Integrate LLVM at llvm/llvm-project@84b0b52b036c
Integrate LLVM at llvm/llvm-project@84b0b52b036c

Updates LLVM usage to match
[84b0b52b036c](https://github.com/llvm/llvm-project/commit/84b0b52b036c)

PiperOrigin-RevId: 401144663

google-research/structured-additive-IR,google-research/structured-additive-IR