<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/130549>130549</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [X86] `acc -= val < 0` converted to less efficient `acc += (val >> 7) & 1`
        </td>
    </tr>

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

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

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

<pre>
    The code:
```c
#include <immintrin.h>
#include <stdint.h>

__m256i count_negative_values(__m256i* src, size_t n) {
    __m256i acc = _mm256_setzero_si256();

    for (size_t i = 0; i < n; i++) {
 __m256i c = _mm256_loadu_si256(src + i);
        __m256i m = _mm256_cmpgt_epi8(_mm256_setzero_si256(), c);
        acc = _mm256_sub_epi8(acc, m);
    }

    return acc;
}
```

with `-O3 -march=haswell` generates a sequence of `vpand` + `vpaddb` for adding to the accumulator, whereas it could produce just `vpsubb`. (if desired, in the unrolled case, it could, to add e.g. `a`,`b`,`c`,`d` to the accumulator without a long `vpsubb` chain, do `acc -= (a+b)+(c+d)`)

https://godbolt.org/z/Wo7qE8MjG
</pre>
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