<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/79822>79822</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [AArch64] Using inout h0 with i16 in inline asm asserts with GlobalISel
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            backend:AArch64
      </td>
    </tr>

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

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

<pre>
    ```llvm
target triple = "aarch64-unknown-linux-gnu"

define i16 @test(i16 %x) {
 %ret = call i16 asm "", "=&{h0},0"(i16 %x)
  ret i16 %ret
}
```
Running this through `llc -O0`  results in:
```
H0 = COPY W8
unimplemented reg-to-reg copy
UNREACHABLE executed at /home/npopov/repos/llvm-project/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp:4739!
```
It works fine if `-O0` is not used.
</pre>
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