Landing: aaa0f6b1e87b
Project / Subsystem
gcc / match.pd
Date
2026-08-24
Author
Kyrylo Tkachov
Commit
aaa0f6b1e87bc62ea15da6eab431af6dcebf6414
Source
github
Perf win
Yes
Breaking
No
All attributes
- project
- gcc
- subsystem
- match.pd
- patch_id
- —
- commit_hash
- aaa0f6b1e87bc62ea15da6eab431af6dcebf6414
- source_type
- github
- headline
- Fold reductions of vector duplicates and repeats [PR127039]
- tldr
- Optimizes vector reductions by folding idempotent operations on duplicate vectors.
- author
- Kyrylo Tkachov
- outcome
- committed
- performance_win
- true
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • optimization
- • vectorization
- • arm
- • sve
- • pr127039
- discussion_id_link
- github:gcc-mirror/gcc#127039
- bugzilla_pr
- —
- date
- 2026-08-24T00:00:00.000Z
This commit enables GCC to fold vector reductions like REDUC_MAX, REDUC_MIN, REDUC_AND, and REDUC_IOR when applied to duplicate vectors. For example, a REDUC_MAX of a vector [x, x, x] now simplifies to x. It also handles XOR reductions on duplicate vectors, folding them to zero if the lane count is provably even, and correctly processes scalable vectors.