<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/61051>61051</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Serialized PTX constant array with aligned vectors is missing padding
        </td>
    </tr>

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

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

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

<pre>
    The following example fails ([here on godbolt](https://godbolt.org/z/YG3Yxa483)) because the constant array of aligned 3-element vectors doesn't have padding between the array's elements, but at the end.
```
typedef __align__(16) float __attribute((__vector_size__(12))) f3;

__constant__ f3 arr[] = {{1,2,3},{4,5,6},{7,8,9}};

__global__ void foo_kernel()
{
 printf("%f, %f, %f\n", arr[1][0], arr[1][1], arr[1][2]);
}
```
This will print `5,6,7` rather than the expected `4,5,6`.

Loading does take into account the padding, so loading `arr[1]` uses an offset of 16 (see godbolt link above), but the array is padded at the end rather than in-between the array elements:
```
.visible .const .align 16 .b8 arr[48] = {0, 0, 128, 63, 0, 0, 0, 64, 0, 0, 64, 64, 0, 0, 128, 64, 0, 0, 160, 64, 0, 0, 192, 64, 0, 0, 224, 64, 0, 0, 0, 65, 0, 0, 16, 65, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
```

The following patch fixes this issue:
[0001-Add-padding-to-vectors-when-serializing-global-const.patch](https://github.com/llvm/llvm-project/files/10850971/0001-Add-padding-to-vectors-when-serializing-global-const.patch)

</pre>
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