<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/136746>136746</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            fshr-related miscompile by AArch64 backend
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            backend:AArch64,
            llvm:codegen,
            miscompilation
      </td>
    </tr>

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

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

<pre>
    here's a function:
```llvm
; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
declare i64 @llvm.fshr.i64(i64, i64, i64) #0

define i1 @f(i64 %0) {
  %2 = or i64 1, %0
  %3 = call i64 @llvm.fshr.i64(i64 %2, i64 %0, i64 0)
  %4 = icmp uge i64 0, %3
  ret i1 %4
}

attributes #0 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }
```
the AArch64 backend lowers it as follows:
```
_f:
        mov     w0, wzr
        ret
```
but `f(0)` should evaluate to 1 (and it does when compiled using Apple's latest clang)

(test case generated by @dtcxzyw's mutator)

</pre>
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