<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/63559>63559</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [GVN] Incorrect non-local load elimination
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            miscompilation,
            llvm:GVN
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

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

<pre>
    Attached test case demonstrates incorrect 'non-local' load elimination.
Basically, test does following:
```
for (i = ... ) {
  array[2] += i;
 array[3] += i;
  array[3] *= -1802;
  array[2] += i;
  array[3] += i;
}
```
but with fancy CFG (and this fancy CFG is required to reproduce issue).
LLVM vectorizes increments of array[2:3] and then GVN removes second vector load not noticing that array[3] element was 
updated between two loads. 
(See BB `latch` where load `%val.array.2_3.3` is eliminated)
[gvn_nonlocal_dep.txt](https://github.com/llvm/llvm-project/files/11885737/gvn_nonlocal_dep.txt)
Attached test renamed to .txt from .ll

Also [Compiler explorer link](https://godbolt.org/z/MbzP6WY38)
</pre>
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