Landing: c74d6b12af61
Project / Subsystem
gcc / match.pd
Date
2026-07-29
Author
Kyrylo Tkachov
Commit
c74d6b12af610318980f76b016ace6b4a28ecbcd
Source
github
Perf win
Yes
Breaking
No
All attributes
- project
- gcc
- subsystem
- match.pd
- patch_id
- —
- commit_hash
- c74d6b12af610318980f76b016ace6b4a28ecbcd
- source_type
- github
- headline
- match.pd: Combine pairs of vector reductions into single operations.
- tldr
- Optimizes vector reductions by combining two separate reductions into a single elementwise operation.
- author
- Kyrylo Tkachov
- outcome
- committed
- performance_win
- true
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • optimization
- • vectorization
- • arm
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-07-29T00:00:00.000Z
This optimization in match.pd combines two vector reductions that feed into the same scalar operation into a single reduction of an elementwise operation. This transformation, REDUC(a) op REDUC(b) -> REDUC(a op b), trades a potentially expensive lane-crossing reduction for a cheaper elementwise operation, significantly reducing instruction count for operations like MIN, MAX, AND, IOR, XOR, and floating-point sums.