Re: [PATCH 6/7] stdlib: Optimization qsort{_r} swap implementation

[Paul Eggert <eggert at cs dot ucla dot edu>]

On 01/22/2018 09:48 AM, Adhemerval Zanella wrote:
> One option I have not
> tested, and which will trade code side for performance; would parametrize
> the qsort creation (as for the 7/7 patch in this set) to have qsort_uint32_t,
> qsort_uint64_t, and qsort_generic for instance (which calls the swap inline).
>
> So we will have something as:
>
> void qsort (void *pbase, size_t total_elems, size_t size)
> {
>    if (size == sizeof (uint32_t)
>      && check_alignment (base, sizeof (uint32_t)))
>      return qsort_uint32_t (pbase, total_elems, size);
>    else if (size == sizeof (uint64_t)
>      && check_alignment (base, sizeof (uint64_t)))
>      return qsort_uint64_t (pbase, total_elems, size);
>    return qsort_generic (pbase, total_elems, size);
> }

Yes, that's the option I was thinking of, except I was thinking that the 
first test should be "if (size == sizeof (void *) && check_alignment 
(base, alignof (void *))) return qsort_voidptr (pbase, total_elems, 
size);" because sorting arrays of pointers is the most common. (Also, 
check_alignment's argument should use alignof not sizeof.)