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      <base href="https://bugs.llvm.org/">
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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - GlobalDCE.cpp / isEmptyFunction doesn't skip debug intrinsics"
   href="https://bugs.llvm.org/show_bug.cgi?id=39669">39669</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>GlobalDCE.cpp / isEmptyFunction doesn't skip debug intrinsics
          </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>DebugInfo
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>aprantl@apple.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>jdevlieghere@apple.com, keith.walker@arm.com, llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>GlobalDCE.cpp / isEmptyFunction is defined as follows:

/// Returns true if F contains only a single "ret" instruction.
static bool isEmptyFunction(Function *F) {
  BasicBlock &Entry = F->getEntryBlock();
  if (Entry.size() != 1 || !isa<ReturnInst>(Entry.front()))
    return false;
  ReturnInst &RI = cast<ReturnInst>(Entry.front());
  return RI.getReturnValue() == nullptr;
}

used thusly:

  // Remove empty functions from the global ctors list.
  Changed |= optimizeGlobalCtorsList(M, isEmptyFunction);


If I'm reading this correctly, this means that the presence of debug info could
change the behavior of the optimization, which would be a bug.</pre>
        </div>
      </p>


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