When building jdk11 with gcc8 on linuxs390x, we run into a couple of warnings of the maybe-uninitialized class. For example

/nightly/jdk11u-dev/src/hotspot/cpu/s390/macroAssembler_s390.cpp:1962:26: error: 'inst' may be used uninitialized in this function [-Werror=maybe-uninitialized]
   return get_pcrel_offset(inst);
          ~~~~~~~~~~~~~~~~^~~~~~
/nightly/jdk11u-dev/src/hotspot/cpu/s390/macroAssembler_s390.cpp:1941:17: note: 'inst' was declared here
   unsigned long inst;
                 ^~~~

Those warnings are switched off in jdk/jdk but not in jdk11. The issues seem to show up only on s390x .