From 8327a035f0b72d2662f53a294680928809408ea9 Mon Sep 17 00:00:00 2001
From: Markus Westerlind <marwes91@gmail.com>
Date: Fri, 25 Jan 2019 20:40:49 +0100
Subject: [PATCH] perf(base): Remove an indirection in aliases

---
 base/src/serialization.rs | 13 ++++++++-----
 base/src/types/mod.rs     | 18 +++++++++---------
 check/src/typ.rs          | 23 ++++++++++++++++-------
 3 files changed, 33 insertions(+), 21 deletions(-)

diff --git a/base/src/serialization.rs b/base/src/serialization.rs
index aa01ebebe3..2bb71d7e3e 100644
--- a/base/src/serialization.rs
+++ b/base/src/serialization.rs
@@ -76,7 +76,7 @@ impl<Id, T> Clone for Seed<Id, T> {
 pub fn deserialize_group<'de, Id, T, D>(
     seed: &mut Seed<Id, T>,
     deserializer: D,
-) -> Result<Arc<Vec<AliasData<Id, T>>>, D::Error>
+) -> Result<Arc<[AliasData<Id, T>]>, D::Error>
 where
     D: crate::serde::Deserializer<'de>,
     T: Clone + From<Type<Id, T>> + ::std::any::Any + DeserializeState<'de, Seed<Id, T>>,
@@ -87,7 +87,7 @@ where
 {
     use crate::serialization::SharedSeed;
     let seed = SharedSeed::new(seed);
-    DeserializeSeed::deserialize(seed, deserializer)
+    DeserializeSeed::deserialize(seed, deserializer).map(|vec: Vec<_>| Arc::from(vec))
 }
 
 impl<'a, T> Shared for &'a T {
@@ -110,7 +110,10 @@ impl Shared for crate::kind::ArcKind {
     }
 }
 
-impl<T> Shared for Arc<T> {
+impl<T> Shared for Arc<T>
+where
+    T: ?Sized,
+{
     fn unique(&self) -> bool {
         Arc::strong_count(self) == 1
     }
@@ -255,7 +258,7 @@ enum Lookup {
 
 fn node_to_id<T>(map: &NodeToId, node: &T) -> Lookup
 where
-    T: Shared,
+    T: ?Sized + Shared,
 {
     if Shared::unique(node) {
         return Lookup::Unique;
@@ -326,7 +329,7 @@ pub mod shared {
     pub fn serialize<S, T, Seed>(self_: &T, serializer: S, seed: &Seed) -> Result<S::Ok, S::Error>
     where
         S: Serializer,
-        T: Shared + Deref,
+        T: ?Sized + Shared + Deref,
         T::Target: SerializeState<Seed>,
         Seed: AsRef<NodeToId>,
     {
diff --git a/base/src/types/mod.rs b/base/src/types/mod.rs
index 990a4df474..0b49d1af91 100644
--- a/base/src/types/mod.rs
+++ b/base/src/types/mod.rs
@@ -423,7 +423,7 @@ where
     }
 
     pub fn group(group: Vec<AliasData<Id, T>>) -> Vec<Alias<Id, T>> {
-        let group = Arc::new(group);
+        let group = Arc::<[_]>::from(group);
         (0..group.len())
             .map(|index| Alias {
                 _typ: T::from(Type::Alias(AliasRef {
@@ -500,7 +500,7 @@ pub struct AliasRef<Id, T> {
         serde(serialize_state_with = "crate::serialization::shared::serialize")
     )]
     /// The other aliases defined in this group
-    pub group: Arc<Vec<AliasData<Id, T>>>,
+    pub group: Arc<[AliasData<Id, T>]>,
 }
 
 impl<Id, T> Eq for AliasRef<Id, T> where AliasData<Id, T>: Eq {}
@@ -535,7 +535,7 @@ impl<Id, T> AliasRef<Id, T> {
     }
 
     #[doc(hidden)]
-    pub fn new(index: usize, group: Arc<Vec<AliasData<Id, T>>>) -> Self {
+    pub fn new(index: usize, group: Arc<[AliasData<Id, T>]>) -> Self {
         AliasRef { index, group }
     }
 
@@ -985,7 +985,7 @@ where
     pub fn alias(name: Id, args: Vec<Generic<Id>>, typ: T) -> T {
         T::from(Type::Alias(AliasRef {
             index: 0,
-            group: Arc::new(vec![AliasData { name, args, typ }]),
+            group: Arc::from(vec![AliasData { name, args, typ }]),
         }))
     }
 
@@ -2932,7 +2932,7 @@ pub trait TypeInterner<Id, T> {
     fn alias(&mut self, name: Id, args: Vec<Generic<Id>>, typ: T) -> T {
         self.intern(Type::Alias(AliasRef {
             index: 0,
-            group: Arc::new(vec![AliasData { name, args, typ }]),
+            group: Arc::from(vec![AliasData { name, args, typ }]),
         }))
     }
 
@@ -2995,14 +2995,14 @@ pub trait TypeInterner<Id, T> {
         Alias {
             _typ: self.intern(Type::Alias(AliasRef {
                 index: 0,
-                group: Arc::new(vec![data]),
+                group: Arc::from(vec![data]),
             })),
             _marker: PhantomData,
         }
     }
 
     fn alias_group(&mut self, group: Vec<AliasData<Id, T>>) -> Vec<Alias<Id, T>> {
-        let group = Arc::new(group);
+        let group = Arc::<[_]>::from(group);
         (0..group.len())
             .map(|index| Alias {
                 _typ: self.intern(Type::Alias(AliasRef {
@@ -3533,7 +3533,7 @@ where
         Type::Ident(ref id) => interner.ident(id.clone()),
         Type::Projection(ref ids) => interner.projection(ids.clone()),
         Type::Alias(ref alias) => {
-            let group = alias
+            let group: Vec<_> = alias
                 .group
                 .iter()
                 .map(|alias_data| translate_alias(alias_data, |a| translate(interner, a)))
@@ -3541,7 +3541,7 @@ where
 
             interner.intern(Type::Alias(AliasRef {
                 index: alias.index,
-                group: Arc::new(group),
+                group: Arc::from(group),
             }))
         }
         Type::EmptyRow => interner.empty_row(),
diff --git a/check/src/typ.rs b/check/src/typ.rs
index 75a52390d0..9dd9b863a5 100644
--- a/check/src/typ.rs
+++ b/check/src/typ.rs
@@ -231,11 +231,14 @@ where
 
 #[doc(hidden)]
 pub trait Ptr {
-    type Target;
+    type Target: ?Sized;
     fn as_ptr(&self) -> &Self::Target;
 }
 
-impl<T> Ptr for Arc<T> {
+impl<T> Ptr for Arc<T>
+where
+    T: ?Sized,
+{
     type Target = T;
     fn as_ptr(&self) -> &Self::Target {
         self
@@ -264,9 +267,12 @@ impl<Id, T> Ptr for Type<Id, T> {
 }
 
 #[repr(transparent)]
-pub struct PtrEq<T>(pub T);
+pub struct PtrEq<T: ?Sized>(pub T);
 
-impl<T> PtrEq<T> {
+impl<T> PtrEq<T>
+where
+    T: ?Sized,
+{
     pub fn new(t: &T) -> &Self {
         unsafe { mem::transmute(t) }
     }
@@ -297,7 +303,10 @@ where
     }
 }
 
-impl<T> Borrow<PtrEq<T>> for PtrEq<Arc<T>> {
+impl<T> Borrow<PtrEq<T>> for PtrEq<Arc<T>>
+where
+    T: ?Sized,
+{
     #[inline(always)]
     fn borrow(&self) -> &PtrEq<T> {
         PtrEq::new(self.0.as_ptr())
@@ -335,7 +344,7 @@ impl TypeInternerAlloc for RcType {
 
 pub struct TranslateInterner<T, U> {
     pub type_map: FnvMap<PtrEq<T>, U>,
-    pub alias_map: FnvMap<PtrEq<Arc<Vec<AliasData<Symbol, T>>>>, Arc<Vec<AliasData<Symbol, U>>>>,
+    pub alias_map: FnvMap<PtrEq<Arc<[AliasData<Symbol, T>]>>, Arc<[AliasData<Symbol, U>]>>,
 }
 
 impl<T, U> Default for TranslateInterner<T, U>
@@ -390,7 +399,7 @@ where
             let group = match type_interner.alias_map.get(PtrEq::new(&alias.group)) {
                 Some(group) => group.clone(),
                 None => {
-                    let group = Arc::new(
+                    let group: Arc<[_]> = Arc::from(
                         alias
                             .group
                             .iter()