Landing: aa65cd8c8d69
Project / Subsystem
gcc / alpha
Date
2026-08-09
Author
Matt Turner
Commit
aa65cd8c8d69a344cffa3c63f21776d458de9914
Source
github
Perf win
No
Breaking
No
All attributes
- project
- gcc
- subsystem
- alpha
- patch_id
- —
- commit_hash
- aa65cd8c8d69a344cffa3c63f21776d458de9914
- source_type
- github
- headline
- alpha: round to odd before narrowing TFmode to SFmode
- tldr
- Fixes incorrect rounding for TFmode to SFmode conversions on Alpha by implementing a round-to-odd strategy.
- author
- Matt Turner
- outcome
- committed
- performance_win
- false
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • alpha
- • floating-point
- • bugfix
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-08-09T00:00:00.000Z
This commit corrects a bug in Alpha’s conversion from TFmode (quad-precision floating-point) to SFmode (single-precision floating-point). Due to the lack of a direct hardware instruction, the conversion passed through DFmode (double-precision) and encountered issues with tie-breaking during the second rounding step. The fix implements a round-to-odd strategy at the last representable fraction bit of DFmode, ensuring correct rounding and preventing underflow flag loss, which resolved issues in glibc’s math test suite.