[llvm] [SLP]Support copyable fmuls in fmuladd, modeled as fmuladd(a, b, -0.0) (PR #213369)

[David Green via llvm-commits]

davemgreen wrote:

Hello. It looks like this is still failing: https://godbolt.org/z/rM7eKf1jM.

https://github.com/llvm/llvm-project/pull/213369