Improve h-sum in dot_avx calculation #7002
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JojiiOfficial
commented
Aug 8, 2025
| let hsum = _mm_hadd_ps(lr_sum, lr_sum); | ||
| let p1 = _mm_extract_ps(hsum, 0); | ||
| let p2 = _mm_extract_ps(hsum, 1); | ||
| f32::from_bits(p1 as u32) + f32::from_bits(p2 as u32) |
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The new implementation uses 1 instruction less: https://godbolt.org/z/5no3W3s9K
IvanPleshkov
approved these changes
Aug 13, 2025
timvisee
approved these changes
Aug 13, 2025
| /// Calculates the hsum (horizontal sum) of four 32 byte registers. | ||
| #[target_feature(enable = "avx")] | ||
| #[allow(clippy::missing_safety_doc)] | ||
| pub unsafe fn four_way_hsum(a: __m256, b: __m256, c: __m256, d: __m256) -> f32 { |
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Does adding #[inline] here make any difference? (I expect not)
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timvisee
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Aug 14, 2025
* Reduce amount of h-sum calculations in dot_avx * Improve HSUM calculation and apply 4way-hsum to other places
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