get rustc_hash from external crate

src/librustc_data_structures/Cargo.toml

@@ -17,6 +17,7 @@ cfg-if = "0.1.2"
 stable_deref_trait = "1.0.0"
 parking_lot_core = "0.2.8"
 rustc-rayon = "0.1.0"
+rustc-hash = "1.0.0"
 
 [dependencies.parking_lot]
 version = "0.5"

src/librustc_data_structures/fx.rs

@@ -10,11 +10,11 @@
 
 use std::collections::{HashMap, HashSet};
 use std::default::Default;
-use std::hash::{Hasher, Hash, BuildHasherDefault};
-use std::ops::BitXor;
+use std::hash::Hash;
 
-pub type FxHashMap<K, V> = HashMap<K, V, BuildHasherDefault<FxHasher>>;
-pub type FxHashSet<V> = HashSet<V, BuildHasherDefault<FxHasher>>;
+pub use rustc_hash::FxHashMap;
+pub use rustc_hash::FxHashSet;
+pub use rustc_hash::FxHasher;
 
 #[allow(non_snake_case)]
 pub fn FxHashMap<K: Hash + Eq, V>() -> FxHashMap<K, V> {
@@ -26,84 +26,3 @@ pub fn FxHashSet<V: Hash + Eq>() -> FxHashSet<V> {
     HashSet::default()
 }
 
-/// A speedy hash algorithm for use within rustc. The hashmap in liballoc
-/// by default uses SipHash which isn't quite as speedy as we want. In the
-/// compiler we're not really worried about DOS attempts, so we use a fast
-/// non-cryptographic hash.
-///
-/// This is the same as the algorithm used by Firefox -- which is a homespun
-/// one not based on any widely-known algorithm -- though modified to produce
-/// 64-bit hash values instead of 32-bit hash values. It consistently
-/// out-performs an FNV-based hash within rustc itself -- the collision rate is
-/// similar or slightly worse than FNV, but the speed of the hash function
-/// itself is much higher because it works on up to 8 bytes at a time.
-pub struct FxHasher {
-    hash: usize
-}
-
-#[cfg(target_pointer_width = "32")]
-const K: usize = 0x9e3779b9;
-#[cfg(target_pointer_width = "64")]
-const K: usize = 0x517cc1b727220a95;
-
-impl Default for FxHasher {
-    #[inline]
-    fn default() -> FxHasher {
-        FxHasher { hash: 0 }
-    }
-}
-
-impl FxHasher {
-    #[inline]
-    fn add_to_hash(&mut self, i: usize) {
-        self.hash = self.hash.rotate_left(5).bitxor(i).wrapping_mul(K);
-    }
-}
-
-impl Hasher for FxHasher {
-    #[inline]
-    fn write(&mut self, bytes: &[u8]) {
-        for byte in bytes {
-            let i = *byte;
-            self.add_to_hash(i as usize);
-        }
-    }
-
-    #[inline]
-    fn write_u8(&mut self, i: u8) {
-        self.add_to_hash(i as usize);
-    }
-
-    #[inline]
-    fn write_u16(&mut self, i: u16) {
-        self.add_to_hash(i as usize);
-    }
-
-    #[inline]
-    fn write_u32(&mut self, i: u32) {
-        self.add_to_hash(i as usize);
-    }
-
-    #[cfg(target_pointer_width = "32")]
-    #[inline]
-    fn write_u64(&mut self, i: u64) {
-        self.add_to_hash(i as usize);
-        self.add_to_hash((i >> 32) as usize);
-    }
-
-    #[cfg(target_pointer_width = "64")]
-    #[inline]
-    fn write_u64(&mut self, i: u64) {
-        self.add_to_hash(i as usize);
-    }
-
-    #[inline]
-    fn write_usize(&mut self, i: usize) {
-        self.add_to_hash(i);
-    }
-
-    #[inline]
-    fn finish(&self) -> u64 {
-        self.hash as u64
-    }
-}

src/librustc_data_structures/lib.rs

@@ -44,6 +44,7 @@ extern crate parking_lot;
 extern crate cfg_if;
 extern crate stable_deref_trait;
 extern crate rustc_rayon as rayon;
+extern crate rustc_hash;
 
 // See librustc_cratesio_shim/Cargo.toml for a comment explaining this.
 #[allow(unused_extern_crates)]