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gh-161127: Let compilers vectorize v_complement() - #161128
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The two's complement of a digit vector is ~a + 1, and the +1 only carries through the trailing zero digits: they stay zero, the first nonzero digit is negated, and the digits above it are just inverted. Written that way no carry is passed between loop iterations, so the loop can be vectorized. v_complement() runs for every bitwise operation with a negative multi-digit operand, up to three times per operation. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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The two's complement of a digit vector is ~a + 1, and the +1 only carries through the trailing zero digits: they stay zero, the first nonzero digit is negated, and the digits above it are just inverted. See corresponding issue for benchmarks.