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Re^14: Module for 128-bit integer math?

by syphilis (Bishop)
on Feb 15, 2011 at 11:14 UTC ( #888200=note: print w/replies, xml ) Need Help??

in reply to Re^13: Module for 128-bit integer math?
in thread Module for 128-bit integer math?

Math::Int128 becomes faster than Math::GMPz, around 60%

Using the latest version of Math::Int128, and your modified script, I find an improvement (on Windows Vista) of around 40%. Given that we're using different operating systems and probably different processors, I think we can agree that "I find the same as you".


I should add that even 40% is better than I could get with my approach to Math::Int128 modifications. I might learn something if I ever find the time and energy to discover why that was so. (Best I could get was to have the int128 arithemtic about 5-10% faster than Math::GMPz.)
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Re^15: Module for 128-bit integer math?
by salva (Abbot) on Feb 15, 2011 at 11:46 UTC

    Well, I have been able to improve Math::Int128 significantly since yesterday. Now, on my computer, it is twice as fast as Math::GMPz running your benchmarks.

    There were two kinds of improvements: providing the 3-argument operators (i.e. uint128_add($to, $a, $b)) and optimizing the SV to int128_t conversions.

    I have also found that the code generated by GCC-current is quite unpredictable. Sometimes things that should be faster are slower. So the tunning I have carried out may be ineffective for your particular version of GCC.

      There were two kinds of improvements: providing the 3-argument operators (i.e. uint128_add($to, $a, $b)) and optimizing the SV to int128_t conversions.

      I think I got the first part handled ok - but I haven't given consideration to the second.
      For the record, my "rough estimation script" (for multiplication only) is as follows - in accordance with the usual mantra that I follow when creating objects:
      package Sis::UInt128; use warnings; use strict; use Math::GMPz qw(:mpz); use Benchmark qw(:all); use Inline C => Config => BUILD_NOISY => 1, TYPEMAPS => ['./typemap_128'], USING => 'ParseRegExp'; use Inline C => <<'EOC'; SV * create() { __uint128 *ps; SV * obj_ref, * obj; New(42, ps, 1, __uint128); if(ps == NULL) croak("Failed to allocate memory in create functio +n"); obj_ref = newSV(0); obj = newSVrv(obj_ref, "Sis::UInt128"); sv_setiv(obj, INT2PTR(IV,ps)); SvREADONLY_on(obj); return obj_ref; } void _assign(__uint128 * rop, SV * h, SV * l) { __uint128 __div = 9223372036854775808ULL; unsigned __int64 high, low; high = (unsigned __int64)SvUV(h); low = (unsigned __int64)SvUV(l); *rop = ((__uint128)__div * high) + (__uint128)low; } void _deref_obj(__uint128 * obj) { dXSARGS; __uint128 __div = 9223372036854775808ULL; ST(0) = sv_2mortal(newSVuv(*obj / __div)); ST(1) = sv_2mortal(newSVuv(*obj % __div)); XSRETURN(2); } void DESTROY(__uint128 * obj) { printf("Cleaning up\n"); Safefree(obj); } void mul_128(__uint128 * rop, __uint128 * op1, __uint128 * op2) { *rop = *op1 * *op2; } EOC our $mpz1 = Math::GMPz->new('676469752303423489'); our $mpz2 = Math::GMPz->new('776469752999423489'); our $mpz_ret = Math::GMPz::Rmpz_init2(128); our $i_ret = create(); our $i_1 = create(); our $i_2 = create(); assign($i_1, "$mpz1"); assign($i_2, "$mpz2"); our $count = 50000; timethese($count * 19, { 'mul_128' => 'mul_128($i_ret, $i_1, $i_2)', 'gmpz' => 'Math::GMPz::Rmpz_mul($mpz_ret, $mpz1, $mpz2)', }); print retrieve($i_1),"\n", retrieve($i_2),"\n", retrieve($i_ret), "\n" +; print "$mpz1\n$mpz2\n$mpz_ret\n"; sub assign { my $obj = shift; my $num = shift; my @args; my $a0 = Math::GMPz->new($num) / 9223372036854775808; my $a1 = Math::GMPz->new($num) % 9223372036854775808; $args[0] = "$a0" + 0; $args[1] = "$a1" + 0; _assign($obj, $args[0], $args[1]); } sub retrieve { my @in = _deref_obj($_[0]); my $num = Math::GMPz->new($in[0]); $num *= 9223372036854775808; $num += $in[1]; return "$num"; }
      with a "typemap_128" that looks like this:
      __uint128 * UI128 INPUT UI128 $var = INT2PTR($type, SvIV(SvRV($arg)))

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