Landing: e6c1179fd40d
Project / Subsystem
gcc / aarch64
Date
2026-05-21
Author
Wilco Dijkstra
Commit
e6c1179fd40d1c22755530d3ae54d4cca8b660f0
Source
github
Perf win
Yes
Breaking
No
All attributes
- project
- gcc
- subsystem
- aarch64
- patch_id
- —
- commit_hash
- e6c1179fd40d1c22755530d3ae54d4cca8b660f0
- source_type
- github
- headline
- AArch64: Prefer w-regs for 32-Bit Move Immediate
- tldr
- GCC now uses w-registers for 32-bit immediate moves on AArch64, potentially improving code density and performance.
- author
- Wilco Dijkstra
- outcome
- committed
- performance_win
- true
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • aarch64
- • code generation
- • optimization
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-05-21T00:00:00.000Z
GCC now prefers using w-registers instead of x-registers for 32-bit immediate move instructions on AArch64. This change can lead to better code density and potentially improved performance, as w-registers are the 32-bit counterparts of the 64-bit x-registers. A new function aarch64_output_move_imm() was added to select w-registers when the immediate value is a 32-bit unsigned integer.