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Re: [PATCH] x86-64: Add sinf with FMA
On 12/8/2017 8:16 AM, Nix wrote:
Yeah, I guess I was wondering if the speedup was actually due to FMA or
some other microarchitectural variation which might not be present on
older FMA-capable processors.
I'm not aware of any system where a FMA would be slower than discrete mul + add...
Even for HSW/BDW they're faster. Now on SKL the performance increase of FMA is *more*
(FMA is 4 cycles, but so are individual add and mul .. so it's really 2x gain)
but that's more upside, not a downside for others.