<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/111794>111794</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            With -Oz Clang should emit xchg instruction
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang
      </td>
    </tr>

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

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

<pre>
    For example, doing a bitwise not operation LLVM emits `mov` instruction instead of `xchg` when `-Oz` (optimize for size is enabled). `xchg` r32/32 requires 1 byte, where `mov` r32/32 2 bytes to encode.

Clang generated (with -Oz) https://godbolt.org/z/sPrTbx9sb
```asm
f:
        mov     eax, edi
        not     eax
        ret
```

With -Oz first `mov` instruction should be replaced with a `xchg`.
</pre>
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