Memory ordering annotations for binary emulation

During source code compilation to a first processor instruction set architecture (ISA), a compiler encounters a memory ordering constraint specified in the source code. The compiler generates binary emulation metadata that is usable during emulation of emitted machine code instructions of the first ISA, in order to enforce the memory ordering constraint within corresponding machine code instructions of a second ISA. An emulator utilizes this binary emulation metadata during emulation of a resulting executable image at a processor implementing the second ISA. When the emulator encounters a machine code instruction in the image that performs a memory operation, it identifies an instruction memory address corresponding to the instruction. The emulator determines whether the binary emulation metadata identifies the instruction memory address as being associated with a memory ordering constraint. If so, the emulator emits machine code instruction(s) in the second ISA that perform the memory operation using a memory barrier.