Rust supports cold code tagging https://doc.rust-lang.org/reference/attributes/codegen.html#the-cold-attribute Also inline and target_feature (SIMD).

• What guidance should we put in the documentation as to when developers should tag code paths as cold, inline, or how to write clean SIMD implementations?
• Do we need to modify the main cargo file and Readme.md for building/testing/benchmarking SIMD specialized code paths?

'cargo bench' currently builds but doesn't seem to run any benchmarks.

`cargo bench --all' runs the gcd benchmark with Criterion output. It runs with text output but gives a warning:

WARNING: HTML report generation will become a non-default optional feature in Criterion.rs 0.4.0.
This feature is being moved to cargo-criterion (https://github.com/bheisler/cargo-criterion) and will be optional in a future version of Criterion.rs. To silence this warning, either switch to cargo-criterion or enable the 'html_reports' feature in your Cargo.toml.