https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59448
--- Comment #19 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- On Tue, 28 Oct 2014, torvald at gcc dot gnu.org wrote: > Alternatively, we could try to be conservative and add an acquire barrier > before the function body if any parameter of the function has > carries_dependency; and, likewise, add an acquire barrier after every call to > a > function which has carries_dependency. > > I don't have more input from the ISO C side, but I would guess that the > situation there is similar. As previously noted: * ISO C does not have carries_dependency (or attributes at all). * carries_dependency is about increasing optimization, not decreasing it. If it affects when barriers are added, it does so by allowing some barriers to be omitted that would otherwise be required.