It does not compile on i386. Error message is:

In file included from src/halfutils.c:3:
src/halfutils.h:27:9: error: controlling expression type '_Float16' not compatible with any generic association type
        return isnan(num);
               ^~~~~~~~~~
/usr/include/math.h:103:2: note: expanded from macro 'isnan'
        __fp_type_select(x, __inline_isnanf, __inline_isnan, __inline_isnanl)
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/math.h:80:62: note: expanded from macro '__fp_type_select'
#define __fp_type_select(x, f, d, ld) __extension__ _Generic((x),       \
                                                             ^~~
1 error generated.
gmake: *** [<builtin>: src/halfutils.o] Error 1
*** Error code 1