Well, at least with Qt (which declares its own assembly atomics at compile time) this was a real issue. When going through the disassembled bitcode files we saw

Well, at least with Qt (which declares its own assembly atomics at compile time) this was a real issue. When going through the disassembled bitcode files we saw that all calls to q_atomic types went through inlined platform-dependent assembly. Of course anything compiled on x64 failed to link on ARM.