>>>>> "Andres" == Andres Freund <andres@anarazel.de> writes:
Andres> Thomas and I are sitting in a cafe and are trying to figure out
Andres> what's going on...
I have a standalone test case:
#include <stdio.h>
#include <math.h>
int main(int argc, char **argv)
{
double d1 = (argc ? 1e180 : 0);
double d2 = (argv ? 1e200 : 0);
int r2 = __builtin_isinf(d1 * d2);
int r1 = isinf(d1 * d2);
printf("r1 = %d, r2 = %d\n", r1, r2);
return 0;
}
Note that swapping the r1 and r2 lines makes the problem disappear (!).
on amd64, clang 3.9.1:
cc -O2 -m32 flttst.c && ./a.out
r1 = 1, r2 = 0
cc -O2 flttst.c && ./a.out
r1 = 1, r2 = 1
Can't reproduce on 32-bit arm.
--
Andrew (irc:RhodiumToad)
