<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/81270>81270</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Missing `__prefetch` builtin on clang-cl for Windwos on Arm
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          everton1984
      </td>
    </tr>
</table>

<pre>
    Looking at the list of intrinsice for ARM64 platform https://learn.microsoft.com/en-us/cpp/intrinsics/arm64-intrinsics?view=msvc-170 in the list we see the `__prefetch()` builtin. I have tried the following code with clang 17.0.6 on my Windows on Arm machine

```
#include <intrin.h>

int main(int argc, char* argv[])
{
        void *address = (void *)0xF11F11;
        __prefetch((void*) address);
        return 0;
}
```
which results in 

```
.\test.cpp(6,2): error: use of undeclared identifier '__prefetch'
    6 | __prefetch((void*) address);
      |         ^
1 error generated.
```

This code compiles perfectly fine with normal `cl`. 
</pre>
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