[clang] [llvm] [InstCombine] Support folding intrinsics into phis (PR #151115)

[Nikita Popov via cfe-commits]

nikic wrote:

Probably need to drop UB implying attributes in case the instruction was speculated... doesn't look like foldOpIntoPhi currently does this.

https://github.com/llvm/llvm-project/pull/151115