gcc/testsuite/gcc.c-torture/execute/991228-1.c

   1 __extension__ union { double d; int i[2]; } u = { d: -0.25 };
   2
   3 /* This assumes the endianness of words in a long long is the same as
   4    that for doubles, which doesn't hold for a few platforms, but we
   5    can probably special case them here, as appropriate.  */
   6 long long endianness_test = 1;
   7 #define MSW (*(int*)&endianness_test)
   8
   9 int
  10 signbit(double x)
  11 {
  12   __extension__ union { double d; int i[2]; } u = { d: x };
  13   return u.i[MSW] < 0;
  14 }
  15
  16 int main(void)
  17 {
  18   if (2*sizeof(int) != sizeof(double) || u.i[MSW] >= 0)
  19     exit(0);
  20
  21   if (!signbit(-0.25))
  22     abort();
  23
  24   exit(0);
  25 }