[LLVMdev] Question about FMA formation
milseman at apple.com
Wed Dec 12 17:14:54 PST 2012
Right now we're shying towards having a re-association helper in codegen-prepare that will re-associate expressions (if allowed). This would allow fast-isel to more easily spot FMA opportunities, and form better code.
On Dec 12, 2012, at 5:11 PM, Eric Christopher <echristo at gmail.com> wrote:
> You hit send right when I did!
> For your example, do you mean that it's grouped like:
> (fadd (fadd (fmul a b) (fmul c d)) e)
> How would your pass go about handling these patterns and is that something that would be too complicated for fast-isel to do on the fly?
> Depends on how they're grouped, but if the formation happens prior to codegen then fast-isel will just handle whatever new instruction you've got. An example of IR would be useful though :)
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