http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46031
Summary: Atomic Builtins page should indicate that 16-byte compare-and-swap is available with -mcex16 Product: gcc Version: unknown Status: UNCONFIRMED Severity: normal Priority: P3 Component: web AssignedTo: unassig...@gcc.gnu.org ReportedBy: justin.lebar+...@gmail.com The atomic builtins page doesn't indicate that gcc supports 16-byte compare-and-swap instructions. But gcc does in fact support this instruction, so the page should indicate that the functionality can be enabled with -mcex16 (or, presumably, with the appropriate -march flag). http://gcc.gnu.org/onlinedocs/gcc/Atomic-Builtins.html