<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/107854>107854</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            LoopVectorize/VPlan asserts "underlying instruction may write to memory" (via PoCL's work-group generation from an OpenCL C code)
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

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

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

<pre>
    I cannot reproduce this one from C/C++, but only via PoCL-generated work-group functions which can sometimes be a bit ... involved. Attached is a reproducer .ll, which produces the crash. It originates from an OpenCL C kernel which has a volatile int as the loop iteration variable, which PoCL (currently, this is a WiP to clean up) converts to per-WI variables. It somehow sneaks the loop down to the assert point and then fails because the load is a volatile.  I'll try to minimize the test case.

```
opt --passes=loop-vectorize vplan-crash.ll -S -o -  
opt: /home/pjaaskel/src/chipStar/llvm-project/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp:80: bool llvm::VPRecipeBase::mayWriteToMemory() const: Assertion `(!I || !I->mayWriteToMemory()) && "underlying instruction may write to memory"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
...
```

[vplan-crash.ll.gz](https://github.com/user-attachments/files/16930255/vplan-crash.ll.gz)
 
</pre>
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