Getting results of _mm256_cmpeq_epi8 - c++

Question

I need to count the number of spaces in a string this way.
There's code:
std::size_t simd256_count_of_spaces(std::string& text) noexcept
{
std::size_t spaces = 0;
for (std::uint64_t i = 0; i < text.length(); i += 32)
{
__m256i __32 =
_mm256_set_epi8(
text[i ], text[i + 1],
text[i + 2], text[i + 3],
text[i + 4], text[i + 5],
text[i + 6], text[i + 7],
text[i + 8], text[i + 9],
text[i + 10], text[i + 11],
text[i + 12], text[i + 13],
text[i + 14], text[i + 15],
text[i + 16], text[i + 17],
text[i + 18], text[i + 19],
text[i + 20], text[i + 21],
text[i + 22], text[i + 23],
text[i + 24], text[i + 25],
text[i + 26], text[i + 27],
text[i + 28], text[i + 29],
text[i + 30], text[i + 31]
);
__m256i __cmp_mask =
_mm256_set_epi8(
32, 32, 32, 32, 32, 32, 32, 32,
32, 32, 32, 32, 32, 32, 32, 32,
32, 32, 32, 32, 32, 32, 32, 32,
32, 32, 32, 32, 32, 32, 32, 32
);
__m256i __cmp_result = _mm256_cmpeq_epi8(__32, __cmp_mask);
// ...
}
}
And i have vector at output like this:
255 255 0 0 0 0 255 0
255 0 0 255 255 0 255 0
255 255 255 0 0 255 255 0
255 255 0 0 0 0 255 0
But, after that, i can get count of count of 255's or 0's in this way:
std::uint8_t* cmp_res = reinterpret_cast<std::uint8_t*>(&__cmp_result);
for (int i = 0; i < 32; i++)
{
if (cmp_res[i] == 255) spaces++;
}
Is it possible to do the same thing(get count of 255's or 0's), but without additional loops?
UPDATE
This code solved my problem:
std::size_t spaces = 0;
const __m256i
__cmp = _mm256_set1_epi8(32);
__m256i __eq = _mm256_cmpeq_epi8(__32, __cmp);
spaces += _popcnt32(_mm256_movemask_epi8(__eq));

Answer 1

Just use for loop, compiler will optimize it for you