This also requires adjustment to code in AArch64ISelLowering so that vector_extract is distributed over strict_fadd.
I don't think you can use MorphNodeTo here. It has a comment about it in the description of the function.
Can it just use one of the ReplaceAllUsesWith/ReplaceAllUsesOfValueWith/CombineTo/etc methods? As far as I understand it needs to replace the old Chain (from N0) with the new one.