[PATCH] x86: emit warnings to avoid potential encoding surprises
Project / Subsystem
binutils / x86
Date
2026-08-14
Proposer
Jan Beulich <jbeulich@suse.com>
Source type
public_inbox
Consensus
Proposed
Sentiment
—/10
Technical tradeoffs
- • Improves safety by warning users about potential unintended instruction encodings.
- • Adds complexity to the assembler's instruction selection logic.
All attributes
- project
- binutils
- subsystem
- x86
- patch_id
- —
- discussion_id
- dcc5f9ab-6f1f-465f-8c55-5643f740b372@suse.com
- source_type
- public_inbox
- title
- [PATCH] x86: emit warnings to avoid potential encoding surprises
- headline
- x86: emit warnings to avoid potential encoding surprises
- tldr
- Adds warnings for x86 instructions that might silently fall back to unintended encodings (e.g., AVX512VL) when specific features are disabled.
- proposer
- Jan Beulich <jbeulich@suse.com>
- consensus
- Proposed
- outcome
- proposed
- sentiment_score
- —
- technical_tradeoffs
-
- • Improves safety by warning users about potential unintended instruction encodings.
- • Adds complexity to the assembler's instruction selection logic.
- series_id
- —
- series_role
- standalone
- series_parts
- []
- tags
-
- • x86
- • assembler
- • AVX512
- • warnings
- • instruction encoding
- bugzilla_url
- —
- date
- 2026-08-14T00:00:00.000Z
[PATCH] x86: emit warnings to avoid potential encoding surprises
This patch introduces warnings in the x86 assembler to alert users when certain instructions might silently fall back to less-specific or unintended encodings. This occurs when newer ISA extensions (like AVX512VL for FMA and F16C, or VNNI and CRC32 variants) are implicitly selected due to feature flags, potentially leading to unexpected behavior if the user’s code is not aware of these extensions. The changes ensure that users are notified of these potential encoding surprises, particularly when using .arch .no* directives or when newer ISA extensions are not explicitly enabled.