[speex-dev] [PATCH] Make SSE Run Time option.

[Jean-Marc Valin]

> Personally, I don't think much of PNI. The complex arithmetic stuff they
> added sets you up for a lot of permute overhead that is inefficient --
> especially on a processor that is already weak on permute. In my opinion,

Actually, the new instructions make it possible to do complex multiplies
without the need to permute and separate the add and subtract. The
really useful instruction here is the "addsubps".

> I find it hard to believe you will never need SSE2.  There are some
> instructions that are legitimately useful to single precision floating
> point work, such as cvtps2dq and cvttps2dq.

There are so few conversions in Speex in the first place that it's not
even bothering with that. You get all the gain from just addps and mulps
(and the "glue instructions" that allows to use them like movaps and
shufps).

        Jean-Marc


-- 
Jean-Marc Valin, M.Sc.A., ing. jr.
LABORIUS (http://www.gel.usherb.ca/laborius)
Université de Sherbrooke, Québec, Canada


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