Landing: 0621cf67366f
Project / Subsystem
gcc / middle-end
Date
2026-08-09
Author
Kael Andrew Alonzo Franco
Commit
0621cf67366ffa2215cdd081b1ca1c3c577e8b70
Source
github
Perf win
No
Breaking
No
All attributes
- project
- gcc
- subsystem
- middle-end
- patch_id
- —
- commit_hash
- 0621cf67366ffa2215cdd081b1ca1c3c577e8b70
- source_type
- github
- headline
- middle-end: Wrong code for a != b | (a|b) != 0. [PR126742]
- tldr
- Fixes incorrect optimization of bitwise operations involving inequality checks.
- author
- Kael Andrew Alonzo Franco
- outcome
- committed
- performance_win
- false
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • optimization
- • bugfix
- • middle-end
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-08-09T00:00:00.000Z
This commit corrects a flawed optimization in GCC’s middle-end related to bitwise operations. The compiler was incorrectly simplifying expressions like (a != b) | ((a|b) != 0) to ((a|b) == 0). The correct logical equivalence is (a != b) | ((a|b) != 0) simplifies to ((a|b) != 0). A test case was updated to more rigorously check the generated code for this specific pattern.