While this may be a bug in gcc, reporting here per https://gcc.gnu.org/bugs/.
https://github.com/anarkiwi/atomgccpuzzle based on Ubuntu 20.04, reproduces a difference in behaviour when the gcc frontend runs on an atom-based CPU via qemu (the same issue occurs outside Docker, and/or when run on an Intel Celeron J series CPU).
$ docker build -f Dockerfile .
[...]
---> Running in cf6eac22eacf
Scanning dependencies of target srsenb_mac
[100%] Building CXX object srsenb/src/stack/mac/CMakeFiles/srsenb_mac.dir/scheduler.cc.o
[100%] Building CXX object srsenb/src/stack/mac/CMakeFiles/srsenb_mac.dir/scheduler_carrier.cc.o
[100%] Building CXX object srsenb/src/stack/mac/CMakeFiles/srsenb_mac.dir/mac.cc.o
[100%] Building CXX object srsenb/src/stack/mac/CMakeFiles/srsenb_mac.dir/ue.cc.o
[100%] Building CXX object srsenb/src/stack/mac/CMakeFiles/srsenb_mac.dir/scheduler_grid.cc.o
[100%] Building CXX object srsenb/src/stack/mac/CMakeFiles/srsenb_mac.dir/scheduler_harq.cc.o
[100%] Building CXX object srsenb/src/stack/mac/CMakeFiles/srsenb_mac.dir/scheduler_metric.cc.o
[100%] Building CXX object srsenb/src/stack/mac/CMakeFiles/srsenb_mac.dir/scheduler_ue.cc.o
In file included from /root/srsLTE/srsenb/hdr/stack/mac/scheduler_common.h:25,
from /root/srsLTE/srsenb/hdr/stack/mac/scheduler_ue.h:25,
from /root/srsLTE/srsenb/hdr/stack/mac/scheduler_grid.h:26,
from /root/srsLTE/srsenb/src/stack/mac/scheduler_grid.cc:22:
/root/srsLTE/lib/include/srslte/adt/bounded_bitset.h: In member function 'srsenb::alloc_outcome_t srsenb::sf_grid_t::alloc_ul_data(srsenb::sched_ue*, srsenb::prb_interval, bool)':
/root/srsLTE/lib/include/srslte/adt/bounded_bitset.h:219:32: error: 'newmask.srslte::bounded_bitset<100, true>::buffer[<unknown>]' may be used uninitialized in this function [-Werror=maybe-uninitialized]
219 | buffer[i] &= other.buffer[i];
| ~~~~~~~~~~~~^
cc1plus: all warnings being treated as errors
make[3]: *** [srsenb/src/stack/mac/CMakeFiles/srsenb_mac.dir/build.make:115: srsenb/src/stack/mac/CMakeFiles/srsenb_mac.dir/scheduler_grid.cc.o] Error 1
make[3]: *** Waiting for unfinished jobs....
make[2]: *** [CMakeFiles/Makefile2:8921: srsenb/src/stack/mac/CMakeFiles/srsenb_mac.dir/all] Error 2
make[1]: *** [CMakeFiles/Makefile2:8928: srsenb/src/stack/mac/CMakeFiles/srsenb_mac.dir/rule] Error 2
make: *** [Makefile:3265: srsenb_mac] Error 2
The command '/bin/sh -c make -j srsenb_mac' returned a non-zero code: 2
However, a docker build without qemu with the exact same source code, installed packages, base image succeeds.
$ docker build -f Dockerfile.ok .
[...]
---> Running in e43b65fff3d1
Scanning dependencies of target srsenb_mac
[100%] Building CXX object srsenb/src/stack/mac/CMakeFiles/srsenb_mac.dir/scheduler_grid.cc.o
[100%] Building CXX object srsenb/src/stack/mac/CMakeFiles/srsenb_mac.dir/scheduler_carrier.cc.o
[100%] Building CXX object srsenb/src/stack/mac/CMakeFiles/srsenb_mac.dir/mac.cc.o
[100%] Building CXX object srsenb/src/stack/mac/CMakeFiles/srsenb_mac.dir/ue.cc.o
[100%] Building CXX object srsenb/src/stack/mac/CMakeFiles/srsenb_mac.dir/scheduler_harq.cc.o
[100%] Building CXX object srsenb/src/stack/mac/CMakeFiles/srsenb_mac.dir/scheduler_metric.cc.o
[100%] Building CXX object srsenb/src/stack/mac/CMakeFiles/srsenb_mac.dir/scheduler.cc.o
[100%] Building CXX object srsenb/src/stack/mac/CMakeFiles/srsenb_mac.dir/scheduler_ue.cc.o
[100%] Linking CXX static library libsrsenb_mac.a
[100%] Built target srsenb_mac
Removing intermediate container e43b65fff3d1
---> b8f0322dc5f2
Step 14/14 : ENTRYPOINT ["/bin/sh"]
---> Running in 46d14114fafc
Removing intermediate container 46d14114fafc
---> 3f781ac8f8bb
Successfully built 3f781ac8f8bb
$ lsb_release -d
Description: Ubuntu 20.04.2 LTS
$ gcc -version
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/9/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:hsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 9.3.0-17ubuntu1~20.04' --with-bugurl=file:///usr/share/doc/gcc-9/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++,gm2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-9 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib --with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none=/build/gcc-9-HskZEa/gcc-9-9.3.0/debian/tmp-nvptx/usr,hsa --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 9.3.0 (Ubuntu 9.3.0-17ubuntu1~20.04)
$ apt-cache policy gcc-9
gcc-9:
Installed: 9.3.0-17ubuntu1~20.04
Candidate: 9.3.0-17ubuntu1~20.04
Version table:
*** 9.3.0-17ubuntu1~20.04 500
500 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 Packages
500 http://security.ubuntu.com/ubuntu focal-security/main amd64 Packages
100 /var/lib/dpkg/status
9.3.0-10ubuntu2 500
500 http://archive.ubuntu.com/ubuntu focal/main amd64 Packages
please recheck with the recent gcc-9 version in 20.04 LTS, and with the default compiler in 22.04 LTS