title: Assembly mov instruction is not recognized
body: <p>I was taught that I could use this instruction:</p>
  
  <pre><code>movl (arr,%r8,4),%eax
  </code></pre>
  
  <p>in case I wanted to do: </p>
  
  <pre><code>%eax=Mem[arr+4*%r8]
  </code></pre>
  
  <p>However this command doesn't seem to be recognized at all and I am getting an error:</p>
  
  <pre><code>Error: Found ',', expected ')'
  Error: junk ',%r8,4)' after expression
  </code></pre>
  
  <p>I can't understand. Is this a real instruction or not?</p>