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Re: [RFA] Zen tuning part 9: Add support for scatter/gather in vectorizer costmodel
On 10/17/2017 07:22 PM, Jan Hubicka wrote:
According to Agner's tables, gathers range from 12 ops (vgatherdpd)
to 66 ops (vpgatherdd). I assume that CPU needs to do following:
In our code, it is basically don't" care" how much work it is for a
gather instruction to do its work.
Without gather the most expensive loop in our code couldn't be
vectorized (there are only a handful of gather instructions in that loop
and dozens of other vector instructions).
Kind regards,
--
Toon Moene - e-mail: toon@moene.org - phone: +31 346 214290
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