[llvm] [SLP]Initial FMAD support (PR #149102)

[Alexey Bataev via llvm-commits]

alexey-bataev wrote:

> @alexey-bataev , could you please take a look at #152683 ? That issue may be related to your change, although we didn't yet do complete bisect.

Yes, looks like it was triggered by this patch. Going to revert it and land again after fixing the issue

https://github.com/llvm/llvm-project/pull/149102