<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/65734>65734</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [AArch64] StringSaver::save(StringRef S) Segmentation fault
        </td>
    </tr>

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

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

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

<pre>
    I ran into a problem using the llvm15 version of `lld`.
It reports a segmentation fault in the function `StringRef StringSaver::save(StringRef S)`.
More specifically, the error was reported inside memcpy.
```
StringRef StringSaver::save(StringRef S) {
  char *P = Alloc.Allocate<char>(S.size() + 1);
  if (!S.empty())
 memcpy(P, S.data(), S.size());
  P[S.size()] = '\0';
  return StringRef(P, S.size());
}
```
Through debugging, I found that it was trying to write to an unwritable memory.

This is that crashing instruction. It is writing the value of `w2` to the position of `x19+w0`. 

This is the register information at the time:

This is the memory data pointed to by the `x19` register:

0xffff7c07eff8 is the memory allocated by Alloc.Allocate. It actually allocates 13 bytes. But

0xffff7c07eff8 ~ 0xffff7c07efff is writeable.
0xffff7c07f000 ~ ... is unwriteable.

This is a probabilistic question, could it be an memory allocation problem in `Alloc.Allocate`?



</pre>
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