Landing: 1f4cc0f7a14b
Project / Subsystem
gcc / match.pd
Date
2026-07-30
Author
Jakub Jelinek
Commit
1f4cc0f7a14b52fdfbd02ac890cc7aedbdfb1979
Source
github
Perf win
No
Breaking
No
All attributes
- project
- gcc
- subsystem
- match.pd
- patch_id
- —
- commit_hash
- 1f4cc0f7a14b52fdfbd02ac890cc7aedbdfb1979
- source_type
- github
- headline
- match.pd: Correct parity(~x) simplification for odd bit-widths.
- tldr
- Fixes incorrect parity calculation for bitwise NOT on odd-width integers.
- author
- Jakub Jelinek
- outcome
- committed
- performance_win
- false
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • optimization
- • bugfix
- • bit-manipulation
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-07-30T00:00:00.000Z
A simplification rule in match.pd incorrectly assumed that parity(~X) is always equivalent to parity(X). This commit corrects that rule, noting that for integer types with an odd number of bits, parity(~X) is actually equivalent to parity(X) ^ 1. This ensures accurate parity calculations for bitwise NOT operations on types with odd precision, fixing PR126471.