<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/137447>137447</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [AArch64] codegen for vector init
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          k-arrows
      </td>
    </tr>
</table>

<pre>
    Consider the following two functions:
https://godbolt.org/z/a9az3h6oq
```c
#include <arm_neon.h>

int8x16_t f(int8_t x)
{
  return (int8x16_t) { x, 0, x, 1, x, 2, x, 3,
                       x, 4, x, 5, x, 6, x, 7 };
}

int8x16_t g(int8_t x)
{
  return (int8x16_t) { 0, x, 1, x, 2, x, 3, x,
 4, x, 5, x, 6, x, 7, x };
}
```

The difference between functions `f` and `g` is only in the parity of the indices, so the assembler output for both functions should be similar.

This issue is motivated by the program in GCC testsuite:
https://github.com/gcc-mirror/gcc/blob/master/gcc/testsuite/gcc.target/aarch64/vec-init-20.c
</pre>
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