2c691af95b
## Proposed Changes Modify the SHA256 implementation in `eth2_hashing` so that it switches between `ring` and `sha2` to take advantage of [x86_64 SHA extensions](https://en.wikipedia.org/wiki/Intel_SHA_extensions). The extensions are available on modern Intel and AMD CPUs, and seem to provide a considerable speed-up: on my Ryzen 5950X it dropped state tree hashing times by about 30% from 35ms to 25ms (on Prater). ## Additional Info The extensions became available in the `sha2` crate [last year](https://www.reddit.com/r/rust/comments/hf2vcx/ann_rustcryptos_sha1_and_sha2_now_support/), and are not available in Ring, which uses a [pure Rust implementation of sha2](https://github.com/briansmith/ring/blob/main/src/digest/sha2.rs). Ring is faster on CPUs that lack the extensions so I've implemented a runtime switch to use `sha2` only when the extensions are available. The runtime switching seems to impose a miniscule penalty (see the benchmarks linked below). |
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| .. | ||
| cached_tree_hash | ||
| fork_choice | ||
| int_to_bytes | ||
| merkle_proof | ||
| proto_array | ||
| safe_arith | ||
| serde_utils | ||
| ssz | ||
| ssz_derive | ||
| ssz_types | ||
| state_processing | ||
| swap_or_not_shuffle | ||
| tree_hash | ||
| tree_hash_derive | ||
| types | ||