Landing: 0cfd3de946ce
Project / Subsystem
gcc / gcc/riscv
Date
2026-08-14
Author
Jeff Law
Commit
0cfd3de946cedafc0948fe4fde5a015c63b8993c
Source
github
Perf win
Yes
Breaking
No
All attributes
- project
- gcc
- subsystem
- gcc/riscv
- patch_id
- —
- commit_hash
- 0cfd3de946cedafc0948fe4fde5a015c63b8993c
- source_type
- github
- headline
- RISC-V cost model adjusted for LO_SUM expressions
- tldr
- RISC-V backend increases cost of LO_SUM expressions to improve code generation.
- author
- Jeff Law
- outcome
- committed
- performance_win
- true
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • risc-v
- • optimization
- • cost model
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-08-14T00:00:00.000Z
The RISC-V GCC backend has slightly increased the cost associated with LO_SUM expressions. This adjustment aims to prevent the Common Subexpression Elimination (CSE) pass from unnecessarily preserving LO_SUM forms when alternative, equivalent values exist. By making LO_SUM costlier, the compiler is encouraged to eliminate them along with associated HIGH expressions, potentially leading to more optimized code.