<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/75730>75730</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Clang-18 crash: Assertion `LC != RTLIB::UNKNOWN_LIBCALL && "Don't know how to expand this XINT_TO_FP!"' failed.
        </td>
    </tr>

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

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

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

<pre>
    Clang-18 with -frounding-math crashes on the test case.
Compiler explorer(assertion trunck): https://godbolt.org/z/MsY6YbGE5
```
$cat mutant.c
float a (void)
{
  return 0x353eab28b46b03ea99b84f9736cd8dbe5e986915a0383c3cb381c0da41e31b3621c75fd53262bfcb1b0e6251dbf00f3988784e29b08b65640c263e4d0959832a20e2ff5245be1e60uwb;
}

$clang-18 -frounding-math mutant.c
mutant.c:3:10: warning: '_BitInt' suffix for literals is a C23 extension [-Wc23-extensions]
    3 |   return 0x353eab28b46b03ea99b84f9736cd8dbe5e986915a0383c3cb381c0da41e31b3621c75fd53262bfcb1b0e6251dbf00f3988784e29b08b65640c263e4d0959832a20e2ff5245be1e60uwb;
 |          ^
fatal error: error in backend: Unsupported library call operation!
clang-18: error: clang frontend command failed with exit code 70 (use -v to see invocation)
Ubuntu clang version 18.0.0 (++20231018091808+48a53509e851-1~exp1~20231018091910.1571)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
clang-18: note: diagnostic msg: 
********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang-18: note: diagnostic msg: /tmp/mutant-31d0f6.c
clang-18: note: diagnostic msg: /tmp/mutant-31d0f6.sh
clang-18: note: diagnostic msg: 

********************
```
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzUVU1vGzcQ_TXUZSCBSy7346CDZFuJUNUOEhlpTgY_ZiU2K3JBcm2lh_z2gpKspOmlaHqpIGBnZ4dD8r03MzJGu3OIcyKWRNxO5Jj2PsytPEjn3ZeDH6OOE-XNl_lNL91uWjTwYtMepl3wozPW7aYHmfagg4x7jOAdpD1CwphAy4gzQm8JXdz4w2B7DIDHofcBA2GNjBFDsnlFGJ3-TFhL-AL2KQ2R8AVhK8JWO2-U79PMhx1hqz8IW_0aP1Wf1Js7cc5MKnr5n19ZqWWCw5ikSzN9dna9lwkkENY8e2vyRufgenk2AAKmMTigRy44SsUaVVaKcpRtq5qya2teadMYhQLbpmoLISlvuOZa8abQ1MiyQF4oXrFC16IzgrOKqU6rQlGsmCiM6ijteNs0dVMiaxVtVCWqkmpWcSwNbUXbcCYZRdZ1gpVCYYEVHV8U4cvX895ejOtdX0n5kY-_AnB94wtO-KKgGegXGZx1u2wSVj8tbVq7RFgNcew6e4TOB-htwiD7CDaChBvGAY8JXcysEbGcftSMT6-uSMTtK6AAHEh9A_8TaC9nvfyIuLsoRybZA4bgQ8bpZIB1oKT-jM5k36OL4zD4kNBAb1WQ4Qto2ffgBwwy65uw4pztla1rqmycnNAF7xI6A9ofDtIZ6KTt0ZyLDY82gfYGoaZZxGNEmD5D8hARwbpnry8bXYT9qEaXxkvqZwwnvopmRmen9YQtCVsyynhBi4a2RUOzr2yk4IK22IhiWnzF41B8_S6oLeisEHVx3WUrww5TvsOxqZ6qcjroaW_deJzu3HgJ2QeUBg7eYJ8DBx_t8fxp7WKSfY_m1oazBldjDIStlHV_h8v5hPlprNw5H5PVcIhn7V5q4Sf-39XUu83d4sMdLLbbxc1b2L69g9XDZvPwcX3_Blbrzd0H2D6c3MvHN_D-7t3D-23uVee1AYfgNcaIBqIfg0bCmkhYC5lRGaPXVmadhNFB1MEO6RoQEPpMIxqQ6ZryH0LAVukwELY61_mUF4Z21Wvx_1SOuP8XXPxXjLy29omZc9PyVk5wXtSU1U1dCDHZzxuhTKUkai5ZY6RRnS5kTWuUhVSypRM7PwmYFTUtmRBiVjFaclFVumiZqFVJSooHaftZ3z8f8pSZ2BhHnNei5nTSS4V9PA1Hxhy-wOkjYSzPyjDPa6Zq3EVS0t7GFL9lSTb1-G1mnsZjRmhxHXqkopsbyL2B38L77Wa9zKzzxeP9L_cPH--fNuvlzWKzAcIqwiogjN3mCq8TfHb-Bfb-JTcAPA5ZW2lvI_y2vt8-bR-eVu9yVsZyLz-3kdlkDP38h8lq035UM-0PhK3yuS-P6RD876gTYavTbSNhqxMafwYAAP__py5jTg">