<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/108109>108109</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [WPD] SPEC 2006 xalancbmk fails with Whole Program Devirtualization turned on.
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang,
            llvm:optimizations
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
            aeubanks,
            teresajohnson
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          UsmanNadeem
      </td>
    </tr>
</table>

<pre>
    Minimal flags to reproduce the issue: `-flto -O0 -fvisibility=hidden -fwhole-program-vtables`
Flag to enable verification trap: `-Wl,-mllvm,-wholeprogramdevirt-check=trap`
I have reproduced the issue with other optimization levels as well. 

With the trap enabled we hit the trap, otherwise we crash with a segmentation fault (failure might be flaky). Execution on QEMU-aarch64 fails more consistently but it can be reproduced on physical devices as well.

We hit the trap in function: `xercesc_2_5::SchemaValidator::preContentValidation(bool, bool)` or `_ZN11xercesc_2_515SchemaValidator20preContentValidationEbb` this function is in `SchemaValidator.cpp`

The devirtualized call is to: `xercesc_2_5::SchemaGrammar::getGrammarType() const` or `_ZNK11xercesc_2_513SchemaGrammar14getGrammarTypeEv`

Debugging reveals that the actual pointer is for: `xercesc_2_5::DTDGrammar::getGrammarType() const` or `_ZNK11xercesc_2_510DTDGrammar14getGrammarTypeEv`
</pre>
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