https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65697
--- Comment #10 from Andrew Macleod <amacleod at redhat dot com> --- (In reply to Matthew Wahab from comment #7) > (In reply to torvald from comment #5) > > (In reply to Matthew Wahab from comment #0) > > > > I don't think that's a precise characterization. The difference discussed > > in that thread is that seq-cst fences have a stronger effect than seq-cst > > stores. This is not really a question of MEMMODEL_SEQ_CST but what you > > apply it to. > > Ok, my point was just that an __sync operation has a stronger barrier that > an __atomic operation. > I think that is just an interpretation problem or flaw in my documentation. It was never meant to indicate any difference between __sync and MEMMODEL_SEQ_CST. Have you tried it on a gcc before __atomic and __sync were merged? probably GCC 4.7 and earlier. The code should be identical. Of course, changes to the machine description patterns could result in differences I suppose... but the intent is that SEQ_CST and __sync are the same... hence the code base was merged. The intention was also to deprecate __sync so I wouldn't put too much thought into it.
