Landing: 10f6223d8338
Project / Subsystem
gcc / middle-end
Date
2026-07-13
Author
Dylan Rees
Commit
10f6223d833874199e17226fbb0c562b69a1e72f
Source
github
Perf win
Yes
Breaking
No
All attributes
- project
- gcc
- subsystem
- middle-end
- patch_id
- —
- commit_hash
- 10f6223d833874199e17226fbb0c562b69a1e72f
- source_type
- github
- headline
- CSE eliminates redundant scalar duplication at different vector widths.
- tldr
- CSE pass now matches and optimizes redundant vector duplications of scalars across different vector widths.
- author
- Dylan Rees
- outcome
- committed
- performance_win
- true
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • optimization
- • CSE
- • vectorization
- • middle-end
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-07-13T00:00:00.000Z
GCC’s Common Subexpression Elimination (CSE) pass now eliminates redundant scalar duplication instructions that arise from low-to-highpart builtins. Previously, identical scalars duplicated into vectors of different widths were placed in separate registers, leading to inefficiency. This fix enables CSE to match these duplicates, emit a single wider vector, and use SUBREGs for narrower uses, optimizing instruction count and potentially enabling single load instructions.