https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127492
Bug ID: 127492
Summary: wrong code with __atomic_add_fetch
Product: gcc
Version: 17.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: kyuwoncho18 at gmail dot com
Target Milestone: ---
### Reproducer
#include <stdio.h>
#include <stdatomic.h>
__int128 v = 1;
int
main (void)
{
__int128 r = __atomic_add_fetch (&v, v, __ATOMIC_RELAXED);
printf ("r=%llu v=%llu\n",
(unsigned long long) r, (unsigned long long) v);
return 0;
}
Output:
$ gcc -O0 -latomic
$ ./a.out
r=2 v=2
$ gcc -O1 -latomic
r=3 v=2
Reproduced with any optimization level, any GCC version, even in 4.9.0, which
is the oldest version I can test.
