Improvements to powerpc32 asm code

[Kevin Ryde]

Mark Rodenkirch <mrodenkirch@wi.rr.com> writes:
>
>              mpn_add_n mpn_add_n_new
> 1             21.1270      #10.0658
> 2             13.0883       #7.0432
> 3             10.0633       #5.7040

I take it this is -C.  -CD is probably best for looking at cycles/limb
loop speeds, since it cancels out fixed overheads.  A plain -c can be
used to look at total times on small sizes.

Torbjorn Granlund <tege@swox.com> writes:
>
> All-in-all, the 7400 is much more similar to 750 (aka G3) than
> to 7450.

For our purposes so far I think 7400 merely a 750 with two extra
completion queue entries. :-)

> (Note that testing potentially buggy assembly routines can cause
> problems with the random number generators of the test programs,
> since they rely on mpn_addmul_1.

tune/many.pl is a good way to run speed.c and try.c on new code.  It's
a bit rough around the edges, but hopefully the comments are enough to
get started.