Landing: d782390469b7
Project / Subsystem
gcc / arm
Date
2026-07-29
Author
Richard Earnshaw
Commit
d782390469b7555f6cf4d8ff29777c941717c5d2
Source
github
Perf win
Yes
Breaking
No
All attributes
- project
- gcc
- subsystem
- arm
- patch_id
- —
- commit_hash
- d782390469b7555f6cf4d8ff29777c941717c5d2
- source_type
- github
- headline
- arm: Thumb2 register preferencing for VFP movsi variant
- tldr
- Improves register allocation for Thumb2 VFP movsi operations, reducing spills.
- author
- Richard Earnshaw
- outcome
- committed
- performance_win
- true
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • arm
- • thumb2
- • vfp
- • register-allocation
- • optimization
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-07-29T00:00:00.000Z
This commit refines register preferencing for the Thumb2 variant of the movsi instruction when using VFP registers. It addresses an issue where the compiler previously hid alternatives from the register allocator, potentially leading to unnecessary spills and reloads between core and VFP registers. The changes aim to align Thumb2 behavior more closely with ARM (A32) mode to improve register utilization.