I think most assemblers know what functions are. There are usually directives to indicate this. They help with emitting symbols (you need the function name to b

I think most assemblers know what functions are. There are usually directives to indicate this. They help with emitting symbols (you need the function name to be emitted or no-one can call it), stack unwind information, and other information (some of which may also be required by the ABI). Here's some relevant documentation for MASM https://learn.microsoft.com/en-us/cpp/assembler/masm/proc?view=msvc-170 https://learn.microsoft.com/en-us/cpp/assembler/masm/proc?vi... The short version of it is that assemblers these days are rarely - if ever - just a zero-context stream of machine instructions. There is far more, some of it actually required.