Comment by bd01

This is pretty bad. Let's start with the very first instruction:

  mov rax, 1

An actual "mov rax, 1" would assemble to 48 B8 01 00 00 00 00 00 00 00, a whopping TEN bytes.

nasm will optimize this to the equivalent "mov eax, 1", that's 6 bytes, but still:

  xor eax, eax ; 2 bytes
  inc eax      ; 2 bytes

would be much smaller. Second line:

  mov rdi, 1

You already have the value 1 in eax, so a "mov edi, eax" (two bytes) would suffice. Etc. etc.