Keep a u32 hash rather than u64 in dynamic_atoms_map::Entry, since that’s all we ever use

Author: SimonSapin

src/atom.rs

@@ -222,7 +222,7 @@ impl<Static: StaticAtomSet> Atom<Static> {
             }
             Dynamic(entry) => {
                 let entry = entry as *mut Entry;
-                u64_hash_as_u32(unsafe { (*entry).hash })
+                unsafe { (*entry).hash }
             }
             Inline(..) => u64_hash_as_u32(self.unsafe_data.get()),
         }
@@ -280,8 +280,12 @@ impl<'a, Static: StaticAtomSet> From<Cow<'a, str>> for Atom<Static> {
                 buf[..len].copy_from_slice(string_to_add.as_bytes());
                 Inline(len as u8, buf)
             } else {
-                let hash = (hash.g as u64) << 32 | (hash.f1 as u64);
-                Dynamic(DYNAMIC_SET.lock().unwrap().insert(string_to_add, hash) as *mut ())
+                Dynamic(
+                    DYNAMIC_SET
+                        .lock()
+                        .unwrap()
+                        .insert(string_to_add, hash.g) as *mut (),
+                )
             }
         };
 

src/dynamic_set.rs

@@ -15,15 +15,15 @@ use std::sync::atomic::Ordering::SeqCst;
 use std::sync::Mutex;
 
 const NB_BUCKETS: usize = 1 << 12; // 4096
-const BUCKET_MASK: u64 = (1 << 12) - 1;
+const BUCKET_MASK: u32 = (1 << 12) - 1;
 
 pub(crate) struct Set {
     buckets: Box<[Option<Box<Entry>>; NB_BUCKETS]>,
 }
 
 pub(crate) struct Entry {
     pub(crate) string: Box<str>,
-    pub(crate) hash: u64,
+    pub(crate) hash: u32,
     pub(crate) ref_count: AtomicIsize,
     next_in_bucket: Option<Box<Entry>>,
 }
@@ -49,7 +49,7 @@ lazy_static! {
 }
 
 impl Set {
-    pub(crate) fn insert(&mut self, string: Cow<str>, hash: u64) -> *mut Entry {
+    pub(crate) fn insert(&mut self, string: Cow<str>, hash: u32) -> *mut Entry {
         let bucket_index = (hash & BUCKET_MASK) as usize;
         {
             let mut ptr: Option<&mut Box<Entry>> = self.buckets[bucket_index].as_mut();