Neville Dipale created ARROW-5303:
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Summary: [Rust] Add SIMD vectorization of numeric casts
Key: ARROW-5303
URL: https://issues.apache.org/jira/browse/ARROW-5303
Project: Apache Arrow
Issue Type: Improvement
Components: Rust
Affects Versions: 0.13.0
Reporter: Neville Dipale
To improve the performance of cast kernels, we need SIMD support in numeric
casts.
An initial exploration shows that we can't trivially add SIMD casts between our
Arrow T::Simd types, because `packed_simd` only supports a cast between T::Simd
types that have the same number of lanes.
This means that adding casts from f64 to i64 (same lane length) satisfies the
bound trait `where TO::Simd : packed_simd::FromCast<FROM::Simd>`, but f64 to
i32 (different lane length) doesn't.
We would benefit from investigating work-arounds to this limitation. Please see
[github::nevi_me::arrow/\{branch:simd-cast}/../kernels/cast.rs|[https://github.com/nevi-me/arrow/blob/simd-cast/rust/arrow/src/compute/kernels/cast.rs#L601]]
for an example implementation that's limited by the differences in lane length.
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