Repository navigation
gh-161127: Let compilers vectorize v_complement() - #161128
Merged
Merged
Conversation
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 <[email protected]>
StanFromIreland
self-requested a review
November 1, 2026 20:13
StanFromIreland
approved these changes
Nov 2, 2026
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
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.