Landing: a6ffae6d7f0f

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Project / Subsystem

gcc / libstdc++

Date

2026-04-30

Author

Jonathan Wakely

Commit

a6ffae6d7f0fb4515103a5f056b691301988268d

Source

github

Perf win

Yes

Breaking

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All attributes

project: gcc
subsystem: libstdc++
patch_id: —
commit_hash: a6ffae6d7f0fb4515103a5f056b691301988268d
source_type: github
headline: libstdc++: Use hardware_destructive_interference_size in atomic.cc.
tldr: The libstdc++ now uses `std::hardware_destructive_interference_size` for aligning atomic variables to improve performance.
author: Jonathan Wakely
outcome: committed
performance_win: true
breaking_change: false
series_id: —
series_parts: []
tags: • libstdc++
• C++
• atomic
• performance
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/a6ffae6d7f0fb4515103a5f056b691301988268d
date: 2026-04-30T00:00:00.000Z

The libstdc++ now uses std::hardware_destructive_interference_size to align atomic variables in atomic.cc. This improves performance by reducing false sharing between threads. The code was moved from a header into the library, making it possible to use std::hardware_destructive_interference_size directly.