<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 mflr/mtlr (link register save/restore) when using inline asm w/ "lr" clobber"
   href="https://bugs.llvm.org/show_bug.cgi?id=50147">50147</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>missing mflr/mtlr (link register save/restore) when using inline asm w/ "lr" clobber
          </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>All
          </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>Backend: PowerPC
          </td>
        </tr>

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

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

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org, natechancellor@gmail.com, nemanja.i.ibm@gmail.com, srhines@google.com, ulrich.weigand@de.ibm.com, uweigand@de.ibm.com
          </td>
        </tr>

        <tr>
          <th>Blocks</th>
          <td>4068
          </td>
        </tr></table>
      <p>
        <div>
        <pre>example:
void foo (void) {
    asm ("":::"lr");
}

powerpc64le-linux-gnu-gcc -O2:
foo:
        mflr 0
        std 0,16(1)
        ld 0,16(1)
        mtlr 0
        blr

clang --target=powerpc64le-linux-gnu -O2:
foo:
        blr

This is causing ppc32 Linux kernels to hang when powering down, resulting in CI
failures, as reported by Nathan Chancellor and debugged by Christophe Leroy in
<a href="https://lists.ozlabs.org/pipermail/linuxppc-dev/2021-April/228246.html">https://lists.ozlabs.org/pipermail/linuxppc-dev/2021-April/228246.html</a>.</pre>
        </div>
      </p>

        <div id="referenced">
          <hr style="border: 1px dashed #969696">
          <b>Referenced Bugs:</b>
          <ul>
              <li>
                [<a class="bz_bug_link 
          bz_status_CONFIRMED "
   title="CONFIRMED - [Meta] Compiling the Linux kernel with clang"
   href="https://bugs.llvm.org/show_bug.cgi?id=4068">Bug 4068</a>] [Meta] Compiling the Linux kernel with clang
              </li>
          </ul>
        </div>
        <br>

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