Rollup merge of #53393 - BurntPizza:serialize-inlines, r=alexcrichton

Mark libserialize functions as inline

Got to thinking: "what if that big pile of tiny functions isn't inlining as it should?"
So a few `replace-regex` later the local perf run says this:
<details>

![](https://i.imgur.com/gvdJEgG.png)
</details>
Not huge, but still a win, which is interesting. Want to verify with the real perf run, but I understand there's a backlog.

I didn't notice any increase in compile time or binary sizes for rustc/libs.

src/libserialize/collection_impls.rs

@@ -17,9 +17,7 @@ use std::collections::{LinkedList, VecDeque, BTreeMap, BTreeSet, HashMap, HashSe
 use std::rc::Rc;
 use std::sync::Arc;
 
-impl<
-    T: Encodable
-> Encodable for LinkedList<T> {
+impl<T: Encodable> Encodable for LinkedList<T> {
     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
         s.emit_seq(self.len(), |s| {
             for (i, e) in self.iter().enumerate() {
@@ -65,10 +63,10 @@ impl<T:Decodable> Decodable for VecDeque<T> {
     }
 }
 
-impl<
-    K: Encodable + PartialEq + Ord,
-    V: Encodable
-> Encodable for BTreeMap<K, V> {
+impl<K, V> Encodable for BTreeMap<K, V>
+    where K: Encodable + PartialEq + Ord,
+          V: Encodable
+{
     fn encode<S: Encoder>(&self, e: &mut S) -> Result<(), S::Error> {
         e.emit_map(self.len(), |e| {
             let mut i = 0;
@@ -82,10 +80,10 @@ impl<
     }
 }
 
-impl<
-    K: Decodable + PartialEq + Ord,
-    V: Decodable
-> Decodable for BTreeMap<K, V> {
+impl<K, V> Decodable for BTreeMap<K, V>
+    where K: Decodable + PartialEq + Ord,
+          V: Decodable
+{
     fn decode<D: Decoder>(d: &mut D) -> Result<BTreeMap<K, V>, D::Error> {
         d.read_map(|d, len| {
             let mut map = BTreeMap::new();
@@ -99,9 +97,9 @@ impl<
     }
 }
 
-impl<
-    T: Encodable + PartialEq + Ord
-> Encodable for BTreeSet<T> {
+impl<T> Encodable for BTreeSet<T>
+    where T: Encodable + PartialEq + Ord
+{
     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
         s.emit_seq(self.len(), |s| {
             let mut i = 0;
@@ -114,9 +112,9 @@ impl<
     }
 }
 
-impl<
-    T: Decodable + PartialEq + Ord
-> Decodable for BTreeSet<T> {
+impl<T> Decodable for BTreeSet<T>
+    where T: Decodable + PartialEq + Ord
+{
     fn decode<D: Decoder>(d: &mut D) -> Result<BTreeSet<T>, D::Error> {
         d.read_seq(|d, len| {
             let mut set = BTreeSet::new();

src/libserialize/leb128.rs

@@ -118,6 +118,7 @@ pub fn write_signed_leb128_to<W>(mut value: i128, mut write: W)
     }
 }
 
+#[inline]
 pub fn write_signed_leb128(out: &mut Vec<u8>, value: i128) {
     write_signed_leb128_to(value, |v| write_to_vec(out, v))
 }

src/libserialize/opaque.rs

@@ -31,6 +31,7 @@ impl Encoder {
         self.data
     }
 
+    #[inline]
     pub fn emit_raw_bytes(&mut self, s: &[u8]) {
         self.data.extend_from_slice(s);
     }
@@ -193,6 +194,7 @@ impl<'a> Decoder<'a> {
         self.position += bytes;
     }
 
+    #[inline]
     pub fn read_raw_bytes(&mut self, s: &mut [u8]) -> Result<(), String> {
         let start = self.position;
         let end = start + s.len();
@@ -326,6 +328,7 @@ impl<'a> serialize::Decoder for Decoder<'a> {
         Ok(Cow::Borrowed(s))
     }
 
+    #[inline]
     fn error(&mut self, err: &str) -> Self::Error {
         err.to_string()
     }

src/libserialize/serialize.rs

@@ -119,6 +119,7 @@ pub trait Encoder {
         self.emit_enum("Option", f)
     }
 
+    #[inline]
     fn emit_option_none(&mut self) -> Result<(), Self::Error> {
         self.emit_enum_variant("None", 0, 0, |_| Ok(()))
     }
@@ -560,14 +561,12 @@ impl< T: Decodable> Decodable for Box<[T]> {
 }
 
 impl<T:Encodable> Encodable for Rc<T> {
-    #[inline]
     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
         (**self).encode(s)
     }
 }
 
 impl<T:Decodable> Decodable for Rc<T> {
-    #[inline]
     fn decode<D: Decoder>(d: &mut D) -> Result<Rc<T>, D::Error> {
         Ok(Rc::new(Decodable::decode(d)?))
     }
@@ -618,7 +617,9 @@ impl<'a, T:Encodable> Encodable for Cow<'a, [T]> where [T]: ToOwned<Owned = Vec<
     }
 }
 
-impl<T:Decodable+ToOwned> Decodable for Cow<'static, [T]> where [T]: ToOwned<Owned = Vec<T>> {
+impl<T:Decodable+ToOwned> Decodable for Cow<'static, [T]>
+    where [T]: ToOwned<Owned = Vec<T>>
+{
     fn decode<D: Decoder>(d: &mut D) -> Result<Cow<'static, [T]>, D::Error> {
         d.read_seq(|d, len| {
             let mut v = Vec::with_capacity(len);