[llvm] [DAGCombiner] Reassociate FMA chains sharing an FMUL (PR #217496)

[Hao Ren via llvm-commits]

nvidia-moomoo wrote:

> Any reason you're doing this in the DAG and not the middleend?

Middle end does not have any FMA fusion, because many decisions in other FMA fusions are target-dependent. As you can see the visitFADDForFMACombine at least depends on `TLI.isFMAFasterThanFMulAndFAdd`

 



https://github.com/llvm/llvm-project/pull/217496