<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/65250>65250</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            CUDA __popc __popcll parameter has wrong signedness
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
      </td>
    </tr>

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

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

<pre>
    According to [CUDA doc](https://docs.nvidia.com/cuda/cuda-math-api/group__CUDA__MATH__INTRINSIC__INT.html#group__CUDA__MATH__INTRINSIC__INT_1g43c9c7d2b9ebf202ff1ef5769989be46), `__popc` and `__popcll` accept unsigned arguments

```cuda
 __device__ ​ int __popc ( unsigned int  x );
 __device__ ​ int __popcll ( unsigned long long int x );
```

but Clang's version is signed

https://github.com/llvm/llvm-project/blob/6098d7d5f6533edb1b873107ddc1acde23b9235b/clang/lib/Headers/__clang_cuda_device_functions.h#L505-L506

While this is mostly harmless, it causes a lot of "narrowing conversion from unsigned to signed is implementation defined" warnings when I was trying to check existing CUDA code with clang-tidy.
</pre>
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