I found my debugging note from/before 2020-06-29: > PGO again via ASLR, filesys, date https://build.opensuse.org/request/show/676711 made it reproducible back then and looking closer at old results, 3.5.2 was the first one marked to differ https://rb.zq1.de/compare.factory-20200303/bison-compare.out Here is the general description of the problem of PGO with reproducibility: https://github.com/bmwiedemann/theunreproduciblepackage/tree/master/pgo Would disabling PGO for bison be an option?