src/vendor/rustc-hash/README.md

   1 # rustc-hash
   2
   3 A speedy hash algorithm used within rustc. The hashmap in liballoc by
   4 default uses SipHash which isn't quite as speedy as we want. In the
   5 compiler we're not really worried about DOS attempts, so we use a fast
   6 non-cryptographic hash.
   7
   8 This is the same as the algorithm used by Firefox -- which is a
   9 homespun one not based on any widely-known algorithm -- though
  10 modified to produce 64-bit hash values instead of 32-bit hash
  11 values. It consistently out-performs an FNV-based hash within rustc
  12 itself -- the collision rate is similar or slightly worse than FNV,
  13 but the speed of the hash function itself is much higher because it
  14 works on up to 8 bytes at a time.
  15
  16 ## Usage
  17
  18 ```
  19 use rustc_hash::FxHashMap;
  20 let map: FxHashMap<u32, u32> = FxHashMap::default();
  21 ```