for beginners, it is really hard to make fast sse code. You have to copy/convert data to the sse unit, and usually that is slower than the gain from vectorize code. In fact, what I always see is a big drop in perfomance when people start to use intrinsics "because they are faster".
Only if you write a complete code using sse intrinsics, with everything in sse registers, with the memory data layout designed to sse, then you will notice a huge gain. That is the case with videocodecs, or raytracing. For an app like kicad, it makes no sense at all to open that gate. ᐧ *Javier Loureiro Varela* On Fri, Apr 29, 2016 at 10:48 AM, Lorenzo Marcantonio < l.marcanto...@cz-dynamic.it> wrote: > On Thu, Apr 28, 2016 at 08:51:58PM +0200, Simon Richter wrote: > > separate sin() and cos() invocations by a single call to sincos(), > > almost cutting computation time in half by computing both at the same > > time using vector instructions. > > I guess that's gcc auto-intrinsic conversion at work. sincos is a single > opcode since the 387 if I remember correctly (and it's faster if the > argument is already normalized). I don't know if it's exploiting some > peculiarity in the polynomial expansion or simply the microcode does > that in parallel... > > Some time ago I did some light testing and the precision is enough for > our fixed point application. Of course integer vector algebra is > preferrable to engaging the FPU (when possible...). OTOH it would be > (maybe) technically possible to parallelize the processor station's work > doing simultaneously integer and FP computation. Don't know if gcc can > do that (since SSE uses the same registers and switching between it and > the FPU is somewhat expensive IIRC). I doubt that this kind of > extreme optimization belongs to kicad anyway! > > -- > Lorenzo Marcantonio > CZ Srl - Parma > > _______________________________________________ > Mailing list: https://launchpad.net/~kicad-developers > Post to : kicad-developers@lists.launchpad.net > Unsubscribe : https://launchpad.net/~kicad-developers > More help : https://help.launchpad.net/ListHelp > >
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