Landing: 0876c8b7f4ed
Project / Subsystem
gcc / libstdc++
Date
2026-07-16
Author
Anlai Lu
Commit
0876c8b7f4ed876e2beba17bc91438934543896b
Source
github
Perf win
Yes
Breaking
No
All attributes
- project
- gcc
- subsystem
- libstdc++
- patch_id
- —
- commit_hash
- 0876c8b7f4ed876e2beba17bc91438934543896b
- source_type
- github
- headline
- libstdc++: Specialize _Iter_sink for ostreambuf_iterator
- tldr
- Optimizes formatting to `std::ostreambuf_iterator` by specializing `_Iter_sink` for bulk writes.
- author
- Anlai Lu
- outcome
- committed
- performance_win
- true
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • libstdc++
- • formatting
- • optimization
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-07-16T00:00:00.000Z
This commit optimizes the formatting library in libstdc++ by adding a partial specialization of _Iter_sink for std::ostreambuf_iterator. This specialization leverages bulk sputn writes and zero-copy put-area operations, replacing per-character sputc calls. It ensures that all counting and truncation logic is handled within the specialization, allowing the base _Streambuf_sink to remain a pure I/O layer and enabling accurate calculation of total output length.