Landing: 253c4edd1d5d
Project / Subsystem
gcc / bitintlower
Date
2026-10-01
Author
Jakub Jelinek
Commit
253c4edd1d5d20d562ca89329d9664812538f0a5
Source
github
Perf win
No
Breaking
No
All attributes
- project
- gcc
- subsystem
- bitintlower
- patch_id
- —
- commit_hash
- 253c4edd1d5d20d562ca89329d9664812538f0a5
- source_type
- github
- headline
- Fix lowering of bswapg/bitreverseg for _BitInt types
- tldr
- GCC fixes miscompilation of _BitInt types in bswapg/bitreverseg operations by correcting how partial limbs are handled.
- author
- Jakub Jelinek
- outcome
- committed
- performance_win
- false
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • optimization
- • compiler bug
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-10-01T00:00:00.000Z
This commit addresses a miscompilation issue in GCC related to the lowering of bswapg and bitreverseg operations for _BitInt types. The problem stemmed from incorrect handling of partial limbs during the lowering process, where optimizations intended for constant indices failed to account for the full bit-reversal logic. The fix ensures that all necessary bits, including those in partial limbs, are correctly processed, preventing incorrect results.