Am 05.10.2018 um 21:08 schrieb Jeff King:
> On Fri, Oct 05, 2018 at 08:48:27PM +0200, René Scharfe wrote:
>> +#define DEFINE_SORT(name, type, compare) \
>> +static int compare##_void(const void *one, const void *two) \
>> +{ \
>> + return compare(one, two); \
>> +} \
>> +static void name(type base, size_t nmemb) \
>> +{ \
>> + const type dummy = NULL; \
>> + if (nmemb > 1) \
>> + qsort(base, nmemb, sizeof(base[0]), compare##_void); \
>> + else if (0) \
>> + compare(dummy, dummy); \
>> +}
>
> I do like that this removes the need to have the code block aspart of
> the macro.
>
> Did you measure to see if there is any runtime impact?
No, but I wouldn't expect any -- the generated code should be the same
in most cases.
Here's an example: https://godbolt.org/z/gwXENy.
> As an aside, we may need to take a "scope" argument in case somebody
> wants to do this in a non-static way.
Sure. (They could easily wrap the static function, but a macro
parameter is simpler still.)
> It would be nice if we could make
> this "static inline", but I don't think even a clever compiler would be
> able to omit the wrapper call.
It could, if it was to inline qsort(3). Current compilers don't do
that AFAIK, but I wouldn't be too surprised if they started to.
The typed comparison function can be inlined into the one with the void
pointers, though.
René
