<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=http://email.email.llvm.org/c/eJylU0tv2zAM_jX2hZjhd-KDD3nAQA9Dg6WH3QJZom2timRIcor--9Fyi3XAbjMISSTFTx8f7o14b4-LVAK4YnqEN-knYM6h9dJoB6hZr1AkcDL3WSoEPyEMRinzJun6cwbGwiTHCS1E6TlKD1GdfkhQH0YKGJhULsr3Ud5AtDtuHqBPmIXggUX5Cfqo-OK53Zi73260P4xinp6-3QJCTgJRcYD1WJx9sOxZgN6sw2bqybTKJ2q0O_-T4RNB7JQCIXFLnzyhGBtclyQJrUo97t9ma34h9x_qukl6pXthdsTV-nNfb2unDHHW48VI7RM-z4SV1XW9QoaKrJS10e93szjQ7I5uZhwD3QNJd7luh4lpofA6I5dMdRcK-874JDUemZP8qAx_3S5Kj5Z5akaU1xsMHD7buGZEkRkV6EQCRLa7_MBxRXtKSHueKVgL0p-2oq0ocH054-C2wp5JIN3A67XIHyFuKxmnWfGWUbIQVafQg7ABZ1obD-aBVrF5uywCKrVoFwaDpov4xaItRFM0LGaLn4xtWW8pU_TxYlU7eT-7NdG8IxkJZekTbu5fOvF3f6RzC9IrXVUUTRZP7ZBnu11TlvuyrnnZlM2-EMUu5ZVoGt43ZaxYj8q1UXUkbhrfIECsPKtz_P8MZJuneZ5meZnneZaVSVFVJQ7Yl83A9pnAqEzxTuVIVpzE2DG2bYDsl9GRU0nn3R8n_aNy1IiBMDH00qugbKNbnb-031s5zyhAaqDZhO4CV8_4qxwk2jjwbAPJ31iVOTI>53391</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [clang] Assertion tripped in X86 FP Stackifier
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          abrachet
      </td>
    </tr>
</table>

<pre>
    Build clang with assertions enabled. Compile the following O1 or higher 
```
void fails() {
    double a, b;
    __asm__ __volatile__("" : "=t"(a) : "f"(b));
}
```
It'll die with `clang: /.../llvm-project/llvm/lib/Target/X86/X86FloatingPoint.cpp:1666: void (anonymous namespace)::FPS::handleSpecialFP(MachineBasicBlock::iterator &): Assertion `(1 << getFPReg(MI.getOperand(I)) & STDefs) == 0 && "Operands with constraint \"f\" cannot overlap with defs"' failed.`
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJxtU8lu3DAM_Rr7QtTwOsvBh1lgIIcig04OvQ1ki7bVaCRDkifI35eSEjQFYhBaSOnp8ZHuNX9vj6uQHAbJ1ARvws3ArEXjhFYWULFeIs_gpO-LkAhuRhi1lPpN0PHnArSBWUwzGkjyc5Ifkk3-YWH70ILDyIS0SblLyj0k22OMAH1crwQPLClP0CfVl8jtxuz9dqP5oSVz9PTtFhBKMkiqA_hldXbBs2MBOnrH6OrJ5e0TNdmev2X4RBBbKYELjOlTJIgR4bosy2iU8nH_sRj9Bwf3sfWToFe6F2Ym9N7fu00cO6mJs5ouWiiXDctCWMVms_GQQRFPWWn1fterBcXuaBc2YKB7IOsu17iYmeISrwsOgsnuQtd-smEWCo_MiuEo9fAaDwqHhjkqRlJuIgwcPsvoM6KbBQl0IgMi211-4eTRnjLaPS90WXHaP0XRPApcX8442ijsmQzyCL7xIn9csVGygXrFGUbJQtKcQg3CBANTSjvQDzSSLfEwD6hUom1oDOou4pfytuL7as9SJ5zENmmOsQjN-UsizohlQQ5CAakM3QWujg2vYhRo0tXIdnZusV6RsiOb6Lm1zwZ9_1Ky_wsprF2R6HRNVe2LdG7ziuOe70dErHMc-dAjbodiV5d1U9S8TiXrUVpPkJJQ-AYBwifUnFPRlnlZ5kVZl2VZFHVWNU2NI_b1fmS7gmNCoHfKOvM8Mm2m1LSBUr9OloJSWGf_BelXFJPCoIfHZ6ubtWlZb6gN0KXh7TZw_wv2XCVQ">