Landing: d9e21f7c4d16
Project / Subsystem
gcc / x86-64
Date
2026-07-17
Author
H.J. Lu
Commit
d9e21f7c4d1666baec96398f07ac500d1c912a12
Source
github
Perf win
Yes
Breaking
No
All attributes
- project
- gcc
- subsystem
- x86-64
- patch_id
- —
- commit_hash
- d9e21f7c4d1666baec96398f07ac500d1c912a12
- source_type
- github
- headline
- x86-64: Enable 128-bit atomic operations by default
- tldr
- Adds -m128bit-atomic flag and enables it by default on compatible x86-64 CPUs to improve performance of 128-bit atomic loads/stores.
- author
- H.J. Lu
- outcome
- committed
- performance_win
- true
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • x86-64
- • atomic
- • performance
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-07-17T00:00:00.000Z
This commit introduces the -m128bit-atomic compiler option, allowing the generation of inline 128-bit atomic loads and stores. This avoids the overhead of calling into the libatomic library for platforms that support these operations. The option is now enabled by default in 64-bit mode for processors supporting x86-64-v3 or later, or AVX-capable processors from major vendors, simplifying the use of efficient atomic operations for developers targeting compatible hardware.