asm for amd64

[Pierrick Gaudry]

Hi,

I have written a few asm functions for the AMD64 architecture (Opteron
and Athlon64). This is not a nice and well-thought assembly support: I've
just translated to 64 bits some of the files of the mpn/x86/k7 directory.

Still, the gain is quite visible. On an Opteron 250 (clocked at 2.4 GHz), I
obtain a gmpbench score of 8850 (instead of 5675 without my patch). 

More information and download at
  http://www.lix.polytechnique.fr/Labo/Pierrick.Gaudry/mpn_AMD64/

Pierrick Gaudry.