Re: [PATCH 1/2] gcc_qsort: source code changes

[David Malcolm <dmalcolm@redhat.com>]

On Thu, 2018-05-10 at 18:56 +0300, Alexander Monakov wrote:
> 	* sort.cc: New file.
>         * system.h [!CHECKING_P] (qsort): Redirect to gcc_qsort.
>         * vec.c (qsort_chk): Use gcc_qsort.

[...snip...]

I'm not a reviewer for this, but there's a lot of fiddly implementation
logic here, so maybe this code could use the selftest framework?

Maybe, in pseudo-code, something like this:

template <typename T>
static void
test_gcc_sort ()
{
   for (creation_strategy in {in-order, backwards}: // and anything else?
     for (int n = 0; n < some_limit; n++)
       {
          make_a_list_of_t (n, creation_strategy)
          gcc_sort (the_list);
          assert that the list is sorted;
	  assert that the number of calls to the callback was sane
     }
}

void
test_gcc_sort_cc ()
{
   test_gcc_sort<int, int_comparator> ();
   test_gcc_sort<long, long_comparator> ();
   // etc; maybe some custom structs to exercise the deterministic property???
}

...or some such, to quickly get coverage of the various list sizes
(which the implementation seems to rely on heavily), in a non-release
build.



Hope this is constructive
Dave