<html>
    <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 - Missing DSE opportunity when second store is done in inline assembly"
   href="https://bugs.llvm.org/show_bug.cgi?id=44913">44913</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Missing DSE opportunity when second store is done in inline assembly
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>libraries
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>trunk
          </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>Scalar Optimizations
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>glider@google.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>florian_hahn@apple.com, llvm-bugs@lists.llvm.org, llvm-bugzilla@jfbastien.com, vitalybuka@google.com
          </td>
        </tr></table>
      <p>
        <div>
        <pre>As reported by Daniel Colascione, Clang fails to remove the dead store in the
following program:

 extern int foo(int* bar);

 int bar()
 {
    int x = 5;
    asm("nop\n\tnop\n\tnop" : "=m" (x));
    return foo(&x);
 }


see <a href="https://gcc.godbolt.org/z/c2fMNH">https://gcc.godbolt.org/z/c2fMNH</a> (bad, clang) vs.
<a href="https://gcc.godbolt.org/z/a_biz5">https://gcc.godbolt.org/z/a_biz5</a> (good, GCC).

This probably prevents it from deleting redundant initialization before
copy_from_user() in the Linux kernel.</pre>
        </div>
      </p>


      <hr>
      <span>You are receiving this mail because:</span>

      <ul>
          <li>You are on the CC list for the bug.</li>
      </ul>
    </body>
</html>