[llvm] [InstCombine] Fold (X * 0.0) * constant => X * 0.0 #85241 (PR #92512)

[Jay Foad via llvm-commits]

https://github.com/jayfoad commented:

There are similar transforms in `InstCombinerImpl::foldFMulReassoc` and they call `ConstantFoldBinaryOpOperands`, _which can fail_, to ensure that the new RHS gets folded to a single constant. So I think you should probably do the same.

https://github.com/llvm/llvm-project/pull/92512