<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 - [ARM64] assert unimplemented reg-to-reg copy"
   href="https://bugs.llvm.org/show_bug.cgi?id=40693">40693</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>[ARM64] assert unimplemented reg-to-reg copy
          </td>
        </tr>

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

        <tr>
          <th>Version</th>
          <td>8.0
          </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>LLVM Codegen
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>al.grant@arm.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Fails on 8.0.0-rc2 at -O1 or higher (-O0 is ok).

clang -O2 --target=aarch64-linux-gnu -march=armv8.1a

void inc128(__int128 *p)
{
        __int128 n, nn;
        do {
                __atomic_load(p, &n, __ATOMIC_RELAXED);
                n = n + 1;
        } while (!__sync_bool_compare_and_swap(p, n, nn));
}</pre>
        </div>
      </p>


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