AMD-64 optimizations, some (new) code

Ashod Nakashian saghmos at
Tue Sep 27 06:43:59 CEST 2005

Torbjorn Granlund wrote:
> [...] There might be
> a bug in speed, or a bug in the compiler with which you compiled
> speed.

If I had more disk space, I'd have compiled and installed gcc 4.0.1 (I 
currently use 3.3.3 and I have hit more than one problem with the 
generated code!)

> 3.3 is definitely good performance.  The GMP development code
> (scheduled for GMP 5) has similar speed (3.0).  I haven't been
> able to get under 3.0, although I have tried hard.

So do you have all major functions ported/optimized for AMD-64, or is 
there some missing stuff? I optimize for the fun of it, so I don't care 
if the same work is already done or not. And no, I don't compete with 
others on performance... I do it for the sheer joy of actually doing it.

Since I'm on the subject, I guess until GMP 5 is released, there will be 
enough AMD-64 code around to undermine the value of GMP 5, to some 
extent at least, since I see you have algorithmic improvements in your 
list of TODO. But then again, one doesn't expect to find all new code 
with the modified/improved algorithms optimized with assembly for most 
cores all in one step. So while having new code with better big-O 
complexity is always more than welcome, it is hard to imagine it be a 
show stopper... not when you have this much effort in assembly-optimized 
code. It will take some time until the new code is also optimized to the 
same caliber as the current one. So, yes, the more you postpone the 
release of the AMD-64 code, the less the value of your effort. Just my 2 


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