That would involve a 100x slowdown in most cases, without dynamic code generation. It's much better to compile multiple versions of the code or multiple binari

That would involve a 100x slowdown in most cases, without dynamic code generation. It's much better to compile multiple versions of the code or multiple binaries. Also, any OS kernel could do transparent emulation like that with no need for CPU assistance (beyond trapping on unsupported instructions, which all modern ISAs of course already do), so it's more of a Linux/Windows ABI issue. You can also write an LD_PRELOAD library that does the emulation.