GMPbench results for Core i7

[Torbjorn Granlund]

I have run GMP 4.3 on a 2.7 GHz Core i7, the latest spin of the
P6 core from Intel.

The processor compiles GMP amazingly fast, faster even than a
high-end AMD system, in just 14 seconds.  But Intel does not
optimise their processors for the kind of instructions we need in
GMP, and the GMPbench results are a bit disappointing.  Please
see http://gmplib.org/gmpbench.html.

I though the corei7 was just an improved core2, but timing the
GMP innerloops indicates that it is more-or-less a different
processor:

                                Core2   Corei7  AMDk10
mpn_add_n/mpn_sub_n             2.03    2.3     1.5
mpn_lshift/mpn_rshift           1.27    1.75    2.37
mpn_mul_1                       4.0     3.8     2.5
mpn_addmul_1/mpn_submul_1       4.5     5.0     2.5
mpn_divrem_1                    25      21      13

The corei7 is sometimes faster, sometimes slower than core2, but
the two processors never seem to execute any of the assembly
inner loops exactly equally.

-- 
Torbjörn