<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/121279>121279</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            MemorySSAUpdater segfaults in deep recursion
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            crash-on-valid
      </td>
    </tr>

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

    <tr>
      <th>Reporter</th>
      <td>
          JonPsson1
      </td>
    </tr>
</table>

<pre>
    clang -cc1 -triple s390x-unknown-linux-gnu -target-cpu z15 -O3 -w -vectorize-loops -vectorize-slp -mllvm -unroll-allow-remainder=false -mllvm -unroll-count=4 -o /dev/null -emit-llvm -x ir crash1_aftercreduce.bugpoint-reduced-simplified.bc

[tc_memssa.tar.gz](https://github.com/user-attachments/files/18268197/tc_memssa.tar.gz)

```
...
#253 0x000002aa3fa2ac9e llvm::MemorySSAUpdater::getPreviousDefFromEnd(llvm::BasicBlock*, llvm::DenseMap<llvm::BasicBlock*, llvm::TrackingVH<llvm::MemoryAccess>, llvm::DenseMapInfo<llvm::BasicBlock*, void>, llvm::detail::DenseMapPair<llvm::BasicBlock*, llvm::TrackingVH<llvm::MemoryAccess>>>&) (/home/ijonpan/llvm-project/install/bin/clang-20+0x102ac9e)
#254 0x000002aa3fa29552 llvm::MemorySSAUpdater::getPreviousDefRecursive(llvm::BasicBlock*, llvm::DenseMap<llvm::BasicBlock*, llvm::TrackingVH<llvm::MemoryAccess>, llvm::DenseMapInfo<llvm::BasicBlock*, void>, llvm::detail::DenseMapPair<llvm::BasicBlock*, llvm::TrackingVH<llvm::MemoryAccess>>>&) (/home/ijonpan/llvm-project/install/bin/clang-20+0x1029552)
#255 0x000002aa3fa2ac9e llvm::MemorySSAUpdater::getPreviousDefFromEnd(llvm::BasicBlock*, llvm::DenseMap<llvm::BasicBlock*, llvm::TrackingVH<llvm::MemoryAccess>, llvm::DenseMapInfo<llvm::BasicBlock*, void>, llvm::detail::DenseMapPair<llvm::BasicBlock*, llvm::TrackingVH<llvm::MemoryAccess>>>&) (/home/ijonpan/llvm-project/install/bin/clang-20+0x102ac9e)
Segmentation fault (core dumped)
```
@nikic @DianQK @whitneywhtsang 
</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJzsll2L4zYXgH-NciNk5GM7iS98kWzWvG_L0mmn7e0iS8eOdmTJ6CPJzK8vSgZmdqYsLRQKZY3AtqTzIT0650iEoCeL2JFmT5rDSqR4dL77wdm7EJwtV4NTj500wk6USVlSFr1eDNJQtfzCkn2w7myZ0TZd2GQTZVH4CSOTS6JPZUPZTxVlZ8pOKKPz-gmZcW4JrzuCWSibjTnNlCXrnTFMGOPOzOMstFXoSXUYhQn4dpp0yUZSHWrKHCXQKzwR6G0yhjKcdWS32ReqPZVehGP5WYwRvfSoksRiSNPitI3s9q9Y0PNi9KhRFYMkfJdbs4_y84xzCKKIwhfTE2kOBLbHGJdAqh2BnkA_6XhMQyHdTKBPAT0TMQp5nNHGQKAftcH8Lrew3pbthkD_Ti20zybX_LnxXVEUuQcqaCrKLzw_IEQ1ChCyRZpXmJ2odp9wdv7x_n7326JEzJuWeyeMdx5P2qVwwLH3bv5oFYHti9xeBC33xskHAjsCH16pPKAN-EkspPrwl-b_6oV80Hb6_X9fSdw820mJIZDq45_b-L8d3bftnJxW78QVRqHN16ruhPb_sMu3BmsCLSWwJdAf3YwEev3F2UVYAn0WZot3X1DGPGBDFMYQ6Aedh68xxIAT2PNLya_0nolnuPUbuG3TwN-E-wvK5IM-4Xe8_z7ezO8V3uZ77P6H4L7E7j1OOcOLqJ2lo0gmZhPSeaQqzQuq5zPwKqOTmlv9oCUlNT9oYX_-MX-djzpafDwfY8i1dqW6SrVVK1bYlZuqqasNr8vVscOBIxd8bLZju-ZjieutaDdCDlU9VM12s9IdcKhLgJaXDa_LohxQqrUacOSNEA2Qmue6aoq86ML5aaVDSNiVUMKmXRkxoAnX-wDAtWgyZ9lJGK0IQL4j-O66XUOaAqm50SGGF11RR4Pd2_NMA07X3QlUW6oQF-pv2crZVfKm-0YxvYJ9jyj7fC2oN7dPHfwRAAD__8lYxTc">