feat: add per-lane popcount on batch - #1401
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With the appropriate credits, https://github.com/WojciechMula/sse-popcount seems to provide relevant implementation for arch-specifics |
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Good point. I also should have listed that the algorithm I implemented I found it on wikipedia. |
Count the bits set in each element of an integer batch. The common kernel is the SWAR fold; x86 uses the PSHUFB nibble lookup from SSSE3 up, NEON uses CNT with pairwise widening adds, SVE uses svcnt_x, and WASM uses i8x16.popcnt with pairwise widening extends, falling back to the common kernel for 64-bit elements. VSX and VXE use vec_popcnt, which the compiler maps to a single VPOPCNTB/H/W/D or VPOPCT. Assisted-by: Claude Opus 5 <noreply@anthropic.com>
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See also https://github.com/kimwalisch/libpopcnt/tree/master based on the paper above for an AVX2 implementation you could add to this PR (with proper credit of course) |
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Count the bits set in each element of an integer batch. The common kernel is the SWAR fold; NEON uses CNT with pairwise widening adds, SVE uses svcnt_x, and WASM uses i8x16.popcnt with pairwise widening extends, falling back to the common kernel for 64-bit elements.
I will add kernels in the future too when I have more of this. I need the bitwise operation for a Morton transform library I am writing.
Creating a new file because I plan to add more functions in the future:
countl_zero/countr_zero, bit_reverse, multishift, bit_deposit/bit_extract, bit_permute + bit_permute_constant, bit_matmul, GFNI kernels.
Reviewed by: Claude Opus 5 noreply@anthropic.com