[llvm] [InstCombine] Fold binary op of reductions. (PR #121567)

[Mikhail Gudim via llvm-commits]

mgudim wrote:

> > I also think reassociate is not the right name.
> 
> reassociate is correct here. For example, this patch converts `(v0 + v1 + v2 + v3) + (v4 + v5 + v6 + v7)` into `(v0 + v4) + (v1 + v5) + (v2 + v6) + (v3 + v7)`.

got it, thanks

https://github.com/llvm/llvm-project/pull/121567