miscompilation with conditional operator side effects (ARM64)

[Роман Донченко]

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 15.04
Release: 15.04
Codename: vivid

$ gcc --version
gcc (Ubuntu/Linaro 4.9.2-10ubuntu13) 4.9.2
Copyright (C) 2014 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ gcc -dumpmachine
aarch64-linux-gnu

$ gcc -O0 -std=c11 repro.c ; ./a.out ; echo $? # repro.c attached
0

$ gcc -O2 -std=c11 repro.c ; ./a.out ; echo $?
1

I don't think this program triggers any undefined behavior, so the optimized version is miscompiled.

I wasn't able to reproduce this with with vanilla 4.9.2.