<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/138819>138819</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            InstSimplify: incorrect frexp(frexp(x)) -> frexp(x) fold
        </td>
    </tr>

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

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

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

<pre>
    It's not ok to fold `frexp(frexp(x))` to `frexp(x)`:

```llvm
; Transforms/InstSimplify/frexp.ll

define {float, i32} @frexp_frexp(float %x) {
  %frexp0 = frexp float %x
  %frexp0.0 = extractvalue {float, i32} %frexp0, 0
  %frexp1 = frexp float %frexp0.0
 ret {float, i32} %frexp1
}
=>
define {float, i32} @frexp_frexp(float %x) {
  %frexp0 = frexp float %x
  ret {float, i32} %frexp0
}
Transformation doesn't verify!

ERROR: Value mismatch

Example:
float %x = #x0000000a (0.000000000000?)

Source:
{float, i32} %frexp0 = { #x3f200000 (0.625), #xffffff6f (4294967151, -145) }
float %frexp0.0 = #x3f200000 (0.625)
{float, i32} %frexp1 = { #x3f200000 (0.625), #x00000000 (0) }

Target:
{float, i32} %frexp0 = { #x3f200000 (0.625), #xffffff6f (4294967151, -145) }
Source value: { #x3f200000 (0.625), #x00000000 (0) }
Target value: { #x3f200000 (0.625), #xffffff6f (4294967151, -145) }
```

cc @arsenm
</pre>
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