This is probably to the gcc maintainer ... I am running on a processor that has compare/exchange 128-bit (cx16 capability), and I compiler with -mcx16 and -latomic. I'm on the latest release cygwin gcc (9.2.0-3, I believe) and the corresponding libatomic. I have a program with this in it:
__atomic_compare_exchange((__int128 *)&s1, (__int128 *)&z, (__int128 *)&s2, 0, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
This compiles to a call (nice if it would inline, but ...) to __atomic_compare_exchange_16, which uses mutex's, not the CMPXCHG16B instruction I was hoping for. Note I am doing dynamic linking, which on at least one other platform results in dynamic selection of a lib_at implementation of the compare/exchange, which does use the desired instruction. Is this a limitation of cygwin gcc, or should I be doing something different to achieve the desired effect? Obviously it would be best not to going an asm inline if I can avoid it, but I suppose I can dig into the libatomic source to get the right incantation for it if need be ... Regards - Eliot Moss "--Problem reports: http://cygwin.com/problems.htmlFAQ: http://cygwin.com/faq/Documentation: http://cygwin.com/docs.htmlUnsubscribe info: http://cygwin.com/ml/#unsubscribe-simple";
