What really happens when I constify and tweak? ;)

[Paolo Carlini <pcarlini at suse dot de>]

Hi,

today, I wanted to start investigating what really happens
when I tweak something here and there...

Indeed, some changes are obviously correct but often, I
realized, I don't know /quantitatively/ the effect.

Consider this instantiation of the __verify_grouping for
chars we had 'til a few days ago:

#include <string>

bool
__verify_grouping(const std::string& __grouping,
                 std::string& __grouping_tmp)
{        
 size_t __i = 0;
 size_t __j = 0;
 const size_t __len = __grouping.size();
 const size_t __n = __grouping_tmp.size();
 bool __test = true;

 while (__test && __i < __n - 1)
   for (__j = 0; __test && __j < __len && __i < __n - 1; ++__j, ++__i)
     __test &= __grouping[__j] == __grouping_tmp[__n - __i - 1];

 __j == __len ? __j = 0 : __j;
 __test &= __grouping[__j] >= __grouping_tmp[__n - __i - 1];
 return __test;
}

Let us begin with a very simple statistic, object file size. So let
us compile it with current mainline on i686-linux, -O2, then strip:

   Size: 1028 bytes.

Then, let us remove the redundant '&' in the loop, as I did recently:

   Size: 984 bytes.

Then, let us constify the second parameter, as I will do later today:

   Size: 656 bytes.

Pretty impressive, isn't it? ;)

Cheers,
Paolo.