title: 64-bit mode does not support 32-bit PUSH and POP instructions
body: <p>NASM returns an error like: &quot;instruction not supported in 64-bit mode&quot;<br />
  (Or with YASM, <code>invalid size for operand 1</code>)</p>
  <p>The subject instructions are <code>pop ecx</code> and <code>push ecx</code>.<br />
  What can I use instead of them or is there an other way to fix this issue?</p>