Landing: 6833708b4eaf
Project / Subsystem
gcc / match-sat-alu.pd
Date
2026-07-30
Author
Kyrylo Tkachov
Commit
6833708b4eaf3ce1c22313bc173ff4253becc86b
Source
github
Perf win
Yes
Breaking
No
All attributes
- project
- gcc
- subsystem
- match-sat-alu.pd
- patch_id
- —
- commit_hash
- 6833708b4eaf3ce1c22313bc173ff4253becc86b
- source_type
- github
- headline
- match-sat-alu.pd: Recognize strict widened unsigned saturation clamps
- tldr
- GCC optimizes unsigned saturating additions where the clamp uses a strict inequality.
- author
- Kyrylo Tkachov
- outcome
- committed
- performance_win
- true
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • optimization
- • gcc
- • aarch64
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-07-30T00:00:00.000Z
GCC’s match-sat-alu.pd pattern matcher now recognizes unsigned saturating additions where the clamping condition uses a strict inequality (< MAX instead of <= MAX). This strict form is equivalent to clamping at MAX - 1 and is now correctly handled, enabling more efficient code generation. An AArch64 example shows a simplification from multiple instructions to a single csinv with a condition code.