Landing: 8b97248edd8f
Project / Subsystem
gcc / gcc/tree-optimization/vect
Date
2026-05-12
Author
Lili Cui
Commit
8b97248edd8f2716d451bfeb369540c0d5338a5d
Source
github
Perf win
Yes
Breaking
No
All attributes
- project
- gcc
- subsystem
- gcc/tree-optimization/vect
- patch_id
- —
- commit_hash
- 8b97248edd8f2716d451bfeb369540c0d5338a5d
- source_type
- github
- headline
- Allow Commutative Operand Swap for IFN in SLP Reduction
- tldr
- GCC can now swap commutative operands in SLP vectorization for internal functions (IFN) like `.COND_ADD`, improving vectorization of code generated by if-conve…
- author
- Lili Cui
- outcome
- committed
- performance_win
- true
- breaking_change
- false
- series_id
- gcc:tree-optimization/vect: allow commutative operand swap for ifn in slp reduction
- series_parts
- []
- tags
-
- • optimization
- • vectorization
- • slp
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-05-12T00:00:00.000Z
GCC’s SLP vectorizer now recognizes commutative operand swaps for internal functions (IFN) generated during if-conversion, such as .COND_ADD. Previously, the vectorizer only recognized commutative swaps for tree_code operations (e.g. PLUS_EXPR), leading to failures when reduction operands appeared in different commutative positions. This change improves performance (7.1% on EMR, 2.48% on Znver5 for 731.astcenc_r with -Ofast).