[Bug target/92462] [arm32] -ftree-pre makes a variable to be wrongly hoisted out

[rguenth at gcc dot gnu.org]

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.