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Performance/betterflatten #3

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Performance/betterflatten #3

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b2a6f9e
Better...
lemire May 14, 2019
a76b812
A bit better.
lemire May 14, 2019
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49 changes: 26 additions & 23 deletions src/main.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -100,53 +100,56 @@ really_inline uint64_t find_quote_mask(simd_input in, uint64_t &prev_iter_inside
// needs to be large enough to handle this
really_inline void flatten_bits(uint32_t *base_ptr, uint32_t &base,
uint32_t idx, uint64_t bits) {
if (bits != 0u) {
// This next line could cost you in some context as it may
// become unpredictable. In other cases, it can be super predictable
// and beneficial.
if (bits == 0) return;
uint32_t cnt = hamming(bits);
uint32_t next_base = base + cnt;
base_ptr[base + 0] = static_cast<uint32_t>(idx) + trailingzeroes(bits);
base_ptr += base;
base_ptr[0] = idx + trailingzeroes(bits);
bits = bits & (bits - 1);
base_ptr[base + 1] = static_cast<uint32_t>(idx) + trailingzeroes(bits);
base_ptr[1] = idx + trailingzeroes(bits);
bits = bits & (bits - 1);
base_ptr[base + 2] = static_cast<uint32_t>(idx) + trailingzeroes(bits);
base_ptr[2] = idx + trailingzeroes(bits);
bits = bits & (bits - 1);
base_ptr[base + 3] = static_cast<uint32_t>(idx) + trailingzeroes(bits);
base_ptr[3] = idx + trailingzeroes(bits);
bits = bits & (bits - 1);
base_ptr[base + 4] = static_cast<uint32_t>(idx) + trailingzeroes(bits);
base_ptr[4] = idx + trailingzeroes(bits);
bits = bits & (bits - 1);
base_ptr[base + 5] = static_cast<uint32_t>(idx) + trailingzeroes(bits);
base_ptr[5] = idx + trailingzeroes(bits);
bits = bits & (bits - 1);
base_ptr[base + 6] = static_cast<uint32_t>(idx) + trailingzeroes(bits);
base_ptr[6] = idx + trailingzeroes(bits);
bits = bits & (bits - 1);
base_ptr[base + 7] = static_cast<uint32_t>(idx) + trailingzeroes(bits);
base_ptr[7] = idx + trailingzeroes(bits);
bits = bits & (bits - 1);
if (cnt > 8) {
base_ptr[base + 8] = static_cast<uint32_t>(idx) + trailingzeroes(bits);
if (cnt > 8) { // hopefully predictable
base_ptr[8] = idx + trailingzeroes(bits);
bits = bits & (bits - 1);
base_ptr[base + 9] = static_cast<uint32_t>(idx) + trailingzeroes(bits);
base_ptr[9] = idx + trailingzeroes(bits);
bits = bits & (bits - 1);
base_ptr[base + 10] = static_cast<uint32_t>(idx) + trailingzeroes(bits);
base_ptr[10] = idx + trailingzeroes(bits);
bits = bits & (bits - 1);
base_ptr[base + 11] = static_cast<uint32_t>(idx) + trailingzeroes(bits);
base_ptr[11] = idx + trailingzeroes(bits);
bits = bits & (bits - 1);
base_ptr[base + 12] = static_cast<uint32_t>(idx) + trailingzeroes(bits);
base_ptr[12] = idx + trailingzeroes(bits);
bits = bits & (bits - 1);
base_ptr[base + 13] = static_cast<uint32_t>(idx) + trailingzeroes(bits);
base_ptr[13] = idx + trailingzeroes(bits);
bits = bits & (bits - 1);
base_ptr[base + 14] = static_cast<uint32_t>(idx) + trailingzeroes(bits);
base_ptr[14] = idx + trailingzeroes(bits);
bits = bits & (bits - 1);
base_ptr[base + 15] = static_cast<uint32_t>(idx) + trailingzeroes(bits);
base_ptr[15] = idx + trailingzeroes(bits);
bits = bits & (bits - 1);
}
if (cnt > 16) {
base += 16;
if (cnt > 16) { // this should never happen
base_ptr += 16;
do {
base_ptr[base] = static_cast<uint32_t>(idx) + trailingzeroes(bits);
base_ptr[base] = idx + trailingzeroes(bits);
bits = bits & (bits - 1);
base++;
base_ptr++;
} while (bits != 0);
}
base = next_base;
}
}

//
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