rust/compiler/rustc_data_structures
bors daf2204aa4 Auto merge of #91837 - Kobzol:stable-hash-map-avoid-sort, r=the8472
Avoid sorting in hash map stable hashing

Suggested by `@the8472` [here](https://github.com/rust-lang/rust/pull/89404#issuecomment-991813333). I hope that I understood it right, I replaced the sort with modular multiplication, which should be commutative.

Can I ask for a perf. run? However, locally it didn't help at all. Creating the `StableHasher` all over again is probably slowing it down quite a lot. And using `FxHasher` is not straightforward, because the keys and values only implement `HashStable` (and probably they shouldn't be just hashed via `Hash` anyway for it to actually be stable).

Maybe the `StableHash` interface could be changed somehow to better suppor these scenarios where the hasher is short-lived. Or the `StableHasher` implementation could have variants with e.g. a shorter buffer for these scenarios.
2021-12-18 21:23:37 +00:00
..
src Auto merge of #91837 - Kobzol:stable-hash-map-avoid-sort, r=the8472 2021-12-18 21:23:37 +00:00
Cargo.toml Update to measureme v10 2021-10-07 15:08:44 +02:00