Landing: 68e0c7bfa12a
Project / Subsystem
gcc / x86
Date
2026-04-15
Author
H.J. Lu
Commit
68e0c7bfa12ab1c7188ac7d8f0d92c22e899a323
Source
github
Perf win
No
Breaking
No
All attributes
- project
- gcc
- subsystem
- x86
- patch_id
- —
- commit_hash
- 68e0c7bfa12ab1c7188ac7d8f0d92c22e899a323
- source_type
- github
- headline
- x86: Remove DI/SI registers from x86_64 integer return registers
- tldr
- The x86-64 ABI only uses AX/DX and XMM0/XMM1 for function returns, so GCC now reflects that.
- author
- H.J. Lu
- outcome
- committed
- performance_win
- false
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • x86-64
- • ABI
- • register allocation
- • calling convention
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-04-15T00:00:00.000Z
GCC now limits the number of registers used for function return values to 2 in 64-bit mode, aligning with the x86-64 ABI. The DI and SI registers were removed from the x86_64_int_return_registers list. This change simplifies register allocation for return values and makes the code more maintainable by adhering to the ABI.