title: What TARGET_HAS_PRECISE_SMC means?
body: <p>I see only x86 define TARGET_HAS_PRECISE_SMC (target-i386/cpu.h), and the
  comment says,</p>
  
  <pre><code>/* support for self modifying code even if the modified instruction is
     close to the modifying instruction */
  #define TARGET_HAS_PRECISE_SMC
  </code></pre>
  
  <p>I would like to know what it means and want to know more about it, but
  googling doesn't help. Would you mind to shed some light on that? Thanks.</p>