<html>
    <head>
      <base href="https://bugs.llvm.org/">
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - `mayReadOrWriteMemory` method behaviour in `Instruction` class"
   href="https://bugs.llvm.org/show_bug.cgi?id=37756">37756</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>`mayReadOrWriteMemory` method behaviour in `Instruction` class
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>new-bugs
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>unspecified
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>All
          </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>new bugs
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>osanwevpk@gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Hello,

In the comment to `mayReadOrWriteMemory` method [1] said that it resurns "true
if this instruction may read or write memory".

Unfortunatelly, if we check both `mayWriteToMemory` and `mayReadFromMemory`
methods [2, 3], they do not check opcode Alloca.
But in language reference said that "the `alloca` instruction allocates
sizeof(<type>)*NumElements bytes of memory on the runtime stack" [4]. Thus, it
is possible to say in other words, that `alloca` instruction modifies memory,
as said in the comment to `mayWriteToMemory` method, and I think this should be
checked in that method.

Or do I understand incorrectly the logic behind `mayReadOrWriteMemory` method?

Thank you,
Petr.

[1]
<a href="https://github.com/llvm-mirror/llvm/blob/master/include/llvm/IR/Instruction.h#L496L498">https://github.com/llvm-mirror/llvm/blob/master/include/llvm/IR/Instruction.h#L496L498</a>
[2]
<a href="https://github.com/llvm-mirror/llvm/blob/master/lib/IR/Instruction.cpp#L523L541">https://github.com/llvm-mirror/llvm/blob/master/lib/IR/Instruction.cpp#L523L541</a>
[3]
<a href="https://github.com/llvm-mirror/llvm/blob/master/lib/IR/Instruction.cpp#L503L521">https://github.com/llvm-mirror/llvm/blob/master/lib/IR/Instruction.cpp#L503L521</a>
[4] <a href="https://llvm.org/docs/LangRef.html#alloca-instruction">https://llvm.org/docs/LangRef.html#alloca-instruction</a></pre>
        </div>
      </p>


      <hr>
      <span>You are receiving this mail because:</span>

      <ul>
          <li>You are on the CC list for the bug.</li>
      </ul>
    </body>
</html>