Landing: b65eb20e8fff
Project / Subsystem
gcc / avr
Date
2026-09-01
Author
Georg-Johann Lay
Commit
b65eb20e8fff1bc572a49fae254055ccfc7799aa
Source
github
Perf win
No
Breaking
No
All attributes
- project
- gcc
- subsystem
- avr
- patch_id
- —
- commit_hash
- b65eb20e8fff1bc572a49fae254055ccfc7799aa
- source_type
- github
- headline
- AVR: Fix 64-bit signed fixed-point multiply
- tldr
- Corrects a bug in AVR's 64-bit signed fixed-point multiplication that mishandled negative numbers.
- author
- Georg-Johann Lay
- outcome
- committed
- performance_win
- false
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • avr
- • libgcc
- • fixed-point
- • multiplication
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-09-01T00:00:00.000Z
The fixed-point multiply routine for 64-bit signed integers on AVR microcontrollers was incorrect for negative numbers. It failed to restore the original value of the B register after the multiplication when B was negative. This patch ensures that B is properly restored by negating it twice if it was negative, preserving the expected register state for the caller.