Aligning std::simd and Rust on Arm v7 Neon float behavior
Nobody has claimed this yet.
Assessment
- Difficulty
- 5/5
- Estimated time
- Over a week
- Newbie friendliness
- 25/100
Research direction
Start by examining std::simd's Arm v7 Neon handling for floating-point operations and compare it with scalar Rust behavior around subnormal values. Determine how the project should preserve Rust's no-flushing guarantee while accounting for Neon registers; done means the behavior is specified and the relevant implementation and tests align.
Written by the indexing model from the issue text.
Description
This is going to be a bit grisly: the Arm v7 Neon registers flush subnormals and Rust has defined floats as to deny flushing subnormals to be a valid behavior. If we want std::simd to align here with scalar ops, we will have to unfortunately kinda chuck the vector ops for non-integer operations.
Meta
rustc --version --verbose:
rustc 1.83.0-nightly (0ee7cb5e3 2024-09-10)
binary: rustc
commit-hash: 0ee7cb5e3633502d9a90a85c3c367eccd59a0aba
commit-date: 2024-09-10
host: x86_64-unknown-linux-gnu
release: 1.83.0-nightly
LLVM version: 19.1.0
- Dominant language
- Rust
- Stars
- 1.1k
- Forks
- 108
- Avg merge
- 22h 53m
- Merged PRs (30d)
- 3
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
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