Re: round4 performance

[Xavier-François Roblot <roblot@euler.univ-lyon1.fr>]

Hi developers,

On Wed, 2004-04-28 at 04:36, Igor Schein wrote:
> Hi,
> 
> here's a polynomial on which round2 heavily outperforms round4:
> 
> x^64 + 528*x^60 + 422640*x^56 + 154189440*x^52 + 46085461920*x^48 + 86643136
> 30464*x^44 + 1067417121457152*x^40 + 76273480007101440*x^36 + 29307987576360
> 23040*x^32 + 31785192406564024320*x^28 + 729662629421496287232*x^24 - 866453
> 9928316858220544*x^20 + 114361270118934673858560*x^16 - 51757447983683584779
> 87840*x^12 + 47264303406943521096007680*x^8 - 774599638688652156020195328*x^
> 4 + 7585622913396815983510880256

I have committed a big patch that attempts to make round4 perform better
with this kind of polynomial. There are some improvements but still it
is significantly slower than round2... Also, I added some garbage
collecting so at least the stack necessary should now be reasonable. In
any case, the changes I have made still require a lot of tunings (and
also probably debugging!), so any feedback is welcome.

Xavier