James Molloy wrote:
Hi,
I've noticed behaviour which doesn't match that described in the GCC
manual for the __sync_bool_compare_and_swap builtin, when operating on
objects of type 'bool'.
Take the following test program as an example, tested on a PowerPC
ibook with GCC 4.3.0:
int main(int argc, char **argv)
{
bool a = true;
// Swap the value 'true' with 'false' and return true on success.
bool b = __sync_bool_compare_and_swap(&a, true, false);
return (b) 2 : 1;
}
This returns '1' - that is, the compare and swap failed - even there
is no reason for it to fail. Interesting to note is that this
behaviour is /not/ exhibited on x86, x86_64 or mips32 (the only other
platforms I was able to test on), and neither is it exhibited if
swapping false with true, for example:
It sounds like a bug. Please file a bug report as indicated here:
http://gcc.gnu.org/bugs.html
Thanks,
David Daney
