Landing: 4b9034d6b240

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Project / Subsystem

gcc / aarch64

Date

2026-09-10

Author

Dominic P

Commit

4b9034d6b240aa2bac3152703c3961b76e30a187

Source

github

Perf win

Yes

Breaking

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All attributes

project: gcc
subsystem: aarch64
patch_id: —
commit_hash: 4b9034d6b240aa2bac3152703c3961b76e30a187
source_type: github
headline: AArch64 sqxtun instructions expressed as unsigned truncate of smax.
tldr: Simplifies AArch64 SIMD saturate and narrow instructions for better pattern matching.
author: Dominic P
outcome: committed
performance_win: true
breaking_change: false
series_id: —
series_parts: []
tags: • aarch64
• optimization
• SIMD
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/4b9034d6b240aa2bac3152703c3961b76e30a187
date: 2026-09-10T00:00:00.000Z

The AArch64 sqxtun and related instructions are now represented using a simpler RTL structure: an unsigned truncate of a signed maximum against zero. This change allows the vectorizer to directly match these patterns, eliminating intermediate instructions and improving code generation efficiency for SIMD operations involving saturation and narrowing.