[Bug c++/63140] wrong code generation probably due to optimization problem

["gcc at boomerangsworld dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63140

--- Comment #11 from Ralf Hoffmann <gcc at boomerangsworld dot de> ---
I managed to create a standalone test program. Attachment "aguix.cc" contains
the stripped down critical code segments. The two other files "aguixtest.cc"
and "aguixtest.hh" are just to make a runnable binary. The attached script
"build" can be used to create the binary.

The expected output is:

wait4mess2 called
waittime2: 5
Worker: msg lock element lost!
Worker: msg lock element lost!
wait4mess2 called

(this is what the binary does with gcc 4.8.1)

while with gcc 4.9.1 it will loop forever:


wait4mess2 called
waittime2: 5
waittime2: 5
waittime2: 5
waittime2: 5
....

Compiled with -O1 instead of -O2 the example program crashes.
Adding -fsanitize=undefined on the other hand will make it work again
regardless of O1 or O2.