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    <head>
      <base href="https://bugs.llvm.org/">
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - __builtin_shuffle parsing bug"
   href="https://bugs.llvm.org/show_bug.cgi?id=37870">37870</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>__builtin_shuffle parsing bug
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>clang
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>unspecified
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Linux
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>enhancement
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>C++
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedclangbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>zhonghao@pku.org.cn
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>dgregor@apple.com, llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>The code is as follow:

typedef int V __attribute__((vector_size (16)));
V a, b, c;

int
foo ()
{
 return __builtin_shuffle (a, b, c)[3];
}

int
main ()
{
 a = (V) { 1, 2, 3, 4 };
 b = (V) { 5, 6, 7, 8 };
 c = (V) { 7, 2, 5, 6 };
 if (foo () != 7)
 __builtin_abort ();
 return 0;
}

clang++ rejects the code with an error message:

error: use of undeclared identifier '__builtin_shuffle'
     return __builtin_shuffle (a, b, c)[3];
            ^
    1 error generated.

The code comes from a gcc bug report:
<a href="https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78089">https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78089</a>

 Jakub Jelinek explained why it is a bug.</pre>
        </div>
      </p>


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