https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63805
Alan Modra <amodra at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |amodra at gmail dot com --- Comment #12 from Alan Modra <amodra at gmail dot com> --- The problem with the both the original testcase and the one in comment #4 is that a 16-byte atomic access is being attempted on an object that is not 16-byte aligned. I'm not sure if that makes the code invalid, or whether it means that powerpc64 should use a locking implementation, but mis-aligned 16-byte atomic loads are not supported by the hardware.