Landing: bb1344be44e3
Project / Subsystem
gcc / tree-vectorizer
Date
2026-08-19
Author
Richard Biener
Commit
bb1344be44e364da8377603697933a668b651c4e
Source
github
Perf win
Yes
Breaking
No
All attributes
- project
- gcc
- subsystem
- tree-vectorizer
- patch_id
- —
- commit_hash
- bb1344be44e364da8377603697933a668b651c4e
- source_type
- github
- headline
- Decide vectorization factor (VF) independently of externals/constants.
- tldr
- Improves vectorization by basing the vectorization factor on assigned types, not external/constant node properties.
- author
- Richard Biener
- outcome
- committed
- performance_win
- true
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • tree-vectorizer
- • optimization
- • SLP
- • performance
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-08-19T00:00:00.000Z
This commit refactors the SLP vectorizer to determine the vectorization factor (VF) based on the assigned SLP_TREE_VECTYPE rather than relying on max_nunits in the SLP graph, which previously included external and constant nodes. These external/constant nodes could artificially inflate the VF, leading to missed optimizations. By decoupling VF calculation from these nodes, the vectorizer can now select a more appropriate VF, resolving issues like ICEs in vect_get_num_copies and improving vectorization efficiency, particularly for code involving invariant data.