[PATCH] D80801: [DAGCombiner] allow more folding of fadd + fmul into fma

[Scott Manley via Phabricator via llvm-commits]

rscottmanley added a comment.

> Not sure if I'm understanding the question. Is there a target or a code pattern with a known disadvantage for the 2 fma variant?

I mostly agree that what you're proposing is an improvement over what's currently there, but my question is that if you're gonna change it, is it really better to do what you're suggesting compared to creating instructions that can be executed in parallel? There are certainly performance differences between fma(a,b,fma(c,d,n)) and a*b + fma(c,d,n) depending on the target.


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  https://reviews.llvm.org/D80801/new/

https://reviews.llvm.org/D80801