integer arithmetics

[John W. Eaton]

On 22-Sep-2008, Jaroslav Hajek wrote:

| this is the first part of my aim to extend & improve performance of
| integer arithmetics in Octave. This patch does not yet implement int64
| operations (though it prepares the ground). Indeed, the only files
| modified by this patch are oct-inttypes.h and oct-inttypes.cc. Apart
| from the octave_int<T> class, the design is mostly rewritten. Due to
| the more specialized code employed, using C++ integer arithmetics
| where possible, integer arithmetics from Octave ends up
| significantly faster.
| 
| Attached is what I got using "benchmark_intmath" from "benchmarks"
| Octave-Forge package, averaged over 5 runs on a non-loaded node of our
| cluster, a 2x dual core AMD Opteron machine on 2.5 GHz with 8 GB RAM,
| Octave compiled with Intel C++ 10.1 at -O2.
| 
| Btw. Speed-up is measured as (old-time/new-time - 1)*100%.
| 
| benchmark results: (averages over 5 runs)
| 
| [...]
| 
|  This patch should not, IMHO, be applied before 3.2.x is forked, so
| I'm sharing mainly for comments.

I tried it but rebuilding fails with:

  g++ -c -I/usr/include/freetype2  -fPIC -I. -I/home/jwe/src/octave/liboctave 
-I.. -I../liboctave -I../src -I../libcruft/misc -I/home/jwe/src/octave 
-I/home/jwe/src/octave/liboctave -I/home/jwe/src/octave/src 
-I/home/jwe/src/octave/libcruft/misc  -DHAVE_CONFIG_H -I/usr/include/freetype2 
-Wall -W -Wshadow -Wold-style-cast -ggdb3 
/home/jwe/src/octave/liboctave/MArray-i.cc -o pic/MArray-i.o
  /home/jwe/src/octave/liboctave/oct-inttypes.h: In static member function 
'static T octave_int_arith_base<T, true>::div(T, T) [with T = signed char]':
  /home/jwe/src/octave/liboctave/oct-inttypes.h:754:   instantiated from 
'octave_int<T> octave_int<T>::operator/(const octave_int<T>&) const [with T = 
signed char]'
  /home/jwe/src/octave/liboctave/MArray.cc:126:   instantiated from 'MArray<T> 
operator/(const MArray<T>&, const T&) [with T = octave_int<signed char>]'
  /home/jwe/src/octave/liboctave/MArray-i.cc:45:   instantiated from here
  /home/jwe/src/octave/liboctave/oct-inttypes.h:640: error: call of overloaded 
'abs(int)' is ambiguous
  /usr/include/c++/4.3/cmath:99: note: candidates are: double std::abs(double)
  /usr/include/c++/4.3/cmath:103: note:                 float std::abs(float)
  /usr/include/c++/4.3/cmath:107: note:                 long double 
std::abs(long double)
  /home/jwe/src/octave/liboctave/oct-inttypes.h:648: error: call of overloaded 
'abs(int)' is ambiguous
  /usr/include/c++/4.3/cmath:99: note: candidates are: double std::abs(double)
  /usr/include/c++/4.3/cmath:103: note:                 float std::abs(float)
  /usr/include/c++/4.3/cmath:107: note:                 long double 
std::abs(long double)
  /home/jwe/src/octave/liboctave/oct-inttypes.h: In static member function 
'static T octave_int_arith_base<T, true>::div(T, T) [with T = short int]':
  /home/jwe/src/octave/liboctave/oct-inttypes.h:754:   instantiated from 
'octave_int<T> octave_int<T>::operator/(const octave_int<T>&) const [with T = 
short int]'
  /home/jwe/src/octave/liboctave/MArray.cc:126:   instantiated from 'MArray<T> 
operator/(const MArray<T>&, const T&) [with T = octave_int<short int>]'
  /home/jwe/src/octave/liboctave/MArray-i.cc:46:   instantiated from here
  /home/jwe/src/octave/liboctave/oct-inttypes.h:640: error: call of overloaded 
'abs(int)' is ambiguous
  /usr/include/c++/4.3/cmath:99: note: candidates are: double std::abs(double)
  /usr/include/c++/4.3/cmath:103: note:                 float std::abs(float)
  /usr/include/c++/4.3/cmath:107: note:                 long double 
std::abs(long double)
  /home/jwe/src/octave/liboctave/oct-inttypes.h:648: error: call of overloaded 
'abs(int)' is ambiguous
  /usr/include/c++/4.3/cmath:99: note: candidates are: double std::abs(double)
  /usr/include/c++/4.3/cmath:103: note:                 float std::abs(float)
  /usr/include/c++/4.3/cmath:107: note:                 long double 
std::abs(long double)
  /home/jwe/src/octave/liboctave/oct-inttypes.h: In static member function 
'static T octave_int_arith_base<T, true>::div(T, T) [with T = int]':
  /home/jwe/src/octave/liboctave/oct-inttypes.h:754:   instantiated from 
'octave_int<T> octave_int<T>::operator/(const octave_int<T>&) const [with T = 
int]'
  /home/jwe/src/octave/liboctave/MArray.cc:126:   instantiated from 'MArray<T> 
operator/(const MArray<T>&, const T&) [with T = octave_int<int>]'
  /home/jwe/src/octave/liboctave/MArray-i.cc:47:   instantiated from here
  /home/jwe/src/octave/liboctave/oct-inttypes.h:640: error: call of overloaded 
'abs(int)' is ambiguous
  /usr/include/c++/4.3/cmath:99: note: candidates are: double std::abs(double)
  /usr/include/c++/4.3/cmath:103: note:                 float std::abs(float)
  /usr/include/c++/4.3/cmath:107: note:                 long double 
std::abs(long double)
  /home/jwe/src/octave/liboctave/oct-inttypes.h:648: error: call of overloaded 
'abs(int)' is ambiguous
  /usr/include/c++/4.3/cmath:99: note: candidates are: double std::abs(double)
  /usr/include/c++/4.3/cmath:103: note:                 float std::abs(float)
  /usr/include/c++/4.3/cmath:107: note:                 long double 
std::abs(long double)
  /home/jwe/src/octave/liboctave/oct-inttypes.h: In static member function 
'static T octave_int_arith_base<T, true>::div(T, T) [with T = long int]':
  /home/jwe/src/octave/liboctave/oct-inttypes.h:754:   instantiated from 
'octave_int<T> octave_int<T>::operator/(const octave_int<T>&) const [with T = 
long int]'
  /home/jwe/src/octave/liboctave/MArray.cc:126:   instantiated from 'MArray<T> 
operator/(const MArray<T>&, const T&) [with T = octave_int<long int>]'
  /home/jwe/src/octave/liboctave/MArray-i.cc:48:   instantiated from here
  /home/jwe/src/octave/liboctave/oct-inttypes.h:640: error: call of overloaded 
'abs(long int)' is ambiguous
  /usr/include/c++/4.3/cmath:99: note: candidates are: double std::abs(double)
  /usr/include/c++/4.3/cmath:103: note:                 float std::abs(float)
  /usr/include/c++/4.3/cmath:107: note:                 long double 
std::abs(long double)
  /home/jwe/src/octave/liboctave/oct-inttypes.h:648: error: call of overloaded 
'abs(long int)' is ambiguous
  /usr/include/c++/4.3/cmath:99: note: candidates are: double std::abs(double)
  /usr/include/c++/4.3/cmath:103: note:                 float std::abs(float)
  /usr/include/c++/4.3/cmath:107: note:                 long double 
std::abs(long double)
  /home/jwe/src/octave/liboctave/oct-inttypes.h: At global scope:
  /home/jwe/src/octave/liboctave/oct-inttypes.h: In instantiation of 'static 
bool octave_int_cmp_op::cf::op(T, T) [with T = unsigned int]':
  /home/jwe/src/octave/liboctave/oct-inttypes.h:204:   instantiated from 
'static T octave_int_base<T>::truncate_int(const S&) [with S = unsigned int, T 
= short unsigned int]'
  /home/jwe/src/octave/liboctave/oct-inttypes.h:373:   instantiated from 
'static T octave_int_arith_base<T, false>::mul(T, T) [with T = short unsigned 
int]'
  /home/jwe/src/octave/liboctave/oct-inttypes.h:753:   instantiated from 
'octave_int<T> octave_int<T>::operator*(const octave_int<T>&) const [with T = 
short unsigned int]'
  /home/jwe/src/octave/liboctave/MArray.cc:125:   instantiated from 'MArray<T> 
operator*(const MArray<T>&, const T&) [with T = octave_int<short unsigned int>]'
  /home/jwe/src/octave/liboctave/MArray-i.cc:56:   instantiated from here
  /home/jwe/src/octave/liboctave/oct-inttypes.h:156: warning: unused parameter 
'x'
  /home/jwe/src/octave/liboctave/oct-inttypes.h:156: warning: unused parameter 
'y'
  /home/jwe/src/octave/liboctave/oct-inttypes.h: In instantiation of 'static 
bool octave_int_cmp_op::cf::op(T, T) [with T = long unsigned int]':
  /home/jwe/src/octave/liboctave/oct-inttypes.h:204:   instantiated from 
'static T octave_int_base<T>::truncate_int(const S&) [with S = long unsigned 
int, T = unsigned int]'
  /home/jwe/src/octave/liboctave/oct-inttypes.h:373:   instantiated from 
'static T octave_int_arith_base<T, false>::mul(T, T) [with T = unsigned int]'
  /home/jwe/src/octave/liboctave/oct-inttypes.h:753:   instantiated from 
'octave_int<T> octave_int<T>::operator*(const octave_int<T>&) const [with T = 
unsigned int]'
  /home/jwe/src/octave/liboctave/MArray.cc:125:   instantiated from 'MArray<T> 
operator*(const MArray<T>&, const T&) [with T = octave_int<unsigned int>]'
  /home/jwe/src/octave/liboctave/MArray-i.cc:57:   instantiated from here
  /home/jwe/src/octave/liboctave/oct-inttypes.h:156: warning: unused parameter 
'x'
  /home/jwe/src/octave/liboctave/oct-inttypes.h:156: warning: unused parameter 
'y'
  make[2]: *** [pic/MArray-i.o] Error 1
  make[2]: Leaving directory `/scratch/jwe/build/octave/liboctave'
  make[1]: *** [liboctave] Error 2
  make[1]: Leaving directory `/scratch/jwe/build/octave'
  make: *** [all] Error 2

Any clues?

jwe