nx_x86_64_call_test.nx

nx_x86_64_call_test.nx -- session 5 smoke for call / return. Builds a program with two functions: func writer(): write(1, "K", 1) ; emits 'K' to stdout (side effect) return 7 ; returns 7 in rax func main(): call writer ; rax = 7 after return rax += 0x30 ; rax = 0x37 ('7') write(1, &rax_byte, 1) ; emits '7' ret 0 Expected stdout: "K7" (hex 4B 37) -- proves: - call dispatches to writer - writer's write side effect happens - writer's return value (7) propagates via rax - main consumes the return value and uses it