Integrate LLVM at llvm/llvm-project@c120edc7b3e1
Integrate LLVM at llvm/llvm-project@c120edc7b3e1

Updates LLVM usage to match
[c120edc7b3e1](https://github.com/llvm/llvm-project/commit/c120edc7b3e1)

PiperOrigin-RevId: 389251785

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