<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/118085>118085</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [AArch64][GlobalISel] ABD operations and combines
        </td>
    </tr>

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

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

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

<pre>
    SDAG, via these nodes can pattern-recognise and optimise abd nodes. We should add the same operations for global isel.

```
  /// ABDS/ABDU - Absolute difference - Return the absolute difference between
  /// two numbers interpreted as signed/unsigned.
  /// i.e trunc(abs(sext(Op0) - sext(Op1))) becomes abds(Op0, Op1)
  ///  or trunc(abs(zext(Op0) - zext(Op1))) becomes abdu(Op0, Op1)
  ABDS,
  ABDU,
```

There are tests in, for example, llvm/test/CodeGen/AArch64/abd-combine.ll.
https://godbolt.org/z/71PGjf486
</pre>
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