title: GCC highest set of instructions compatible with multiple architectures
body: <p>I am running jobs on a cluster composed of machines with different architectures:
  <code>gcc -march=native -Q --help=target | grep -- '-march=' | cut -f3</code> gives me one of these: <code>broadwell</code>, <code>haswell</code>, <code>ivybridge</code>, <code>sandybridge</code> or <code>skylake</code>.</p>
  
  <p>The executable needs to be the same, so I cannot use <code>-march=native</code> but at the same time the architectures have things in common (I think they all support AVX?).</p>
  
  <p>I am aware that <code>gcc</code> (contrary to Intel <code>icc</code>) does not allow for multiple archictures in a single executable. What I would like to know is if there is a way to ask <code>gcc</code> for the highest set of instructions compatible with all the architectures listed above.</p>
  
  <p>gcc version: 8.1.1</p>