Re: [PATCH] AArch64: Optimize ADD relocations that resolve to zero
Project / Subsystem
binutils / aarch64
Date
2026-08-13
Proposer
Alice Carlotti <alice.carlotti@arm.com>
Source type
public_inbox
Consensus
Proposed
Sentiment
—/10
Technical tradeoffs
- • Performing the optimization improves code density and potentially performance but risks correctness if relocations are still active.
- • Adding checks for relocation status increases complexity in the linker.
All attributes
- project
- binutils
- subsystem
- aarch64
- patch_id
- —
- discussion_id
- cc2a28f2-e71d-9054-4e42-c61a8b772668@e124511.cambridge.arm.com
- source_type
- public_inbox
- title
- Re: [PATCH] AArch64: Optimize ADD relocations that resolve to zero
- headline
- AArch64 ADD relocation optimization invalid with pending relocations
- tldr
- Reviewer flags that optimizing ADD instructions to MOV/NOP when relocations resolve to zero is invalid if the linker still emits relocations, as it breaks idem…
- proposer
- Alice Carlotti <alice.carlotti@arm.com>
- consensus
- Proposed
- outcome
- needs_revision
- sentiment_score
- —
- technical_tradeoffs
-
- • Performing the optimization improves code density and potentially performance but risks correctness if relocations are still active.
- • Adding checks for relocation status increases complexity in the linker.
- series_id
- —
- series_role
- standalone
- series_parts
- []
- tags
-
- • ld
- • aarch64
- • optimization
- • relocation
- • review
- url
- https://inbox.sourceware.org/binutils/cc2a28f2-e71d-9054-4e42-c61a8b772668@e124511.cambridge.arm.com
- bugzilla_url
- —
- date
- 2026-08-13T00:00:00.000Z
Re: [PATCH] AArch64: Optimize ADD relocations that resolve to zero
A reviewer has raised a concern regarding a proposed optimization for AArch64 ADD instructions. The optimization replaces ADD instructions whose immediate value becomes zero after relocation with MOV or NOP instructions. The reviewer argues this is invalid if the linker continues to emit relocations for these instructions, as it breaks idempotency. Further clarification from maintainers is requested on how to check for this condition.