https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92462
--- Comment #15 from Richard Biener <rguenth at gcc dot gnu.org> --- I can't find PRE doing anything wrong and on 32bit x86_64 the testcase executes correctly with GCC 7.3 and GCC 9 (when I add the missing return to Bar::cmpxchg). So -ftree-pre, if it triggers a bug, triggers it elsewhere, the bug isn't in PRE itself AFAICS.
