Landing: 49e640dc4675
Project / Subsystem
gcc / match-sat-alu.pd
Date
2026-08-21
Author
Kyrylo Tkachov
Commit
49e640dc4675de1f48166906a11950cb6698e77f
Source
github
Perf win
Yes
Breaking
No
All attributes
- project
- gcc
- subsystem
- match-sat-alu.pd
- patch_id
- —
- commit_hash
- 49e640dc4675de1f48166906a11950cb6698e77f
- source_type
- github
- headline
- match-sat-alu.pd: Recognize signed saturating truncation after a shift
- tldr
- GCC now optimizes signed saturating truncation that follows an arithmetic right shift, simplifying code.
- 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
- 2026-08-21T00:00:00.000Z
GCC’s match-sat-alu.pd pattern matcher can now recognize and optimize signed saturating truncation that occurs after an arithmetic right shift. This optimization allows the saturation value to use the original input while the shift operates on the already shifted value. This can simplify complex code sequences, such as an AArch64 example that reduces to a single SQSHRN instruction.