Ludovic Courtès wrote:
> On `alphaev56-dec-osf5.1b', NaN handling seems to be deeply broken.
> Consider this piece of code:
>
> --8<---------------cut here---------------start------------->8---
> #include <math.h>
>
> extern unsigned int DQNAN[2];
>
> int
> main (int argc, char *argv[])
> {
> return isnan (* (double *) DQNAN);
> }
> --8<---------------cut here---------------end--------------->8---
>
> When compiled with GCC 4.0.2, it bails out with SIGFPE.
What's the result when you compile it with cc?
$ cc foo.c -lm
$ ./a.out
$ echo $?
What's the result for a program that uses a quiet NaN, computed
differently?
#include <math.h>
double zero = 0.0;
int main()
{
return isnan (zero / zero);
};
And finally, what's the hexdump of that DQNAN constant?
#include <math.h>
#include <stdio.h>
int main()
{
printf("%04X%04X\n", DQNAN[1], DQNAN[0]);
return 0;
}
Bruno
