https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103699
Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|WAITING |RESOLVED Resolution|--- |INVALID --- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Basically you have an aliasing violation. You are writing as an uint64_t but then reading as uint32_t. Use either -fno-strict-aliasing or add may_alias attribute to UnalignedUInt32 and UnalignedUInt64.