2 files changed, 10 insertions, 25 deletions
diff --git a/compiler/rustc_data_structures/src/base_n.rs b/compiler/rustc_data_structures/src/base_n.rs
index 4567759c004..58704350706 100644
--- a/compiler/rustc_data_structures/src/base_n.rs
+++ b/compiler/rustc_data_structures/src/base_n.rs
@@ -16,22 +16,21 @@ const BASE_64: &[u8; MAX_BASE] =
 pub fn push_str(mut n: u128, base: usize, output: &mut String) {
     debug_assert!(base >= 2 && base <= MAX_BASE);
     let mut s = [0u8; 128];
-    let mut index = 0;
+    let mut index = s.len();
 
     let base = base as u128;
 
     loop {
+        index -= 1;
         s[index] = BASE_64[(n % base) as usize];
-        index += 1;
         n /= base;
 
         if n == 0 {
             break;
         }
     }
-    s[0..index].reverse();
 
-    output.push_str(str::from_utf8(&s[0..index]).unwrap());
+    output.push_str(str::from_utf8(&s[index..]).unwrap());
 }
 
 #[inline]
diff --git a/compiler/rustc_data_structures/src/sync/vec.rs b/compiler/rustc_data_structures/src/sync/vec.rs
index e36dded9e5e..314496ce9f0 100644
--- a/compiler/rustc_data_structures/src/sync/vec.rs
+++ b/compiler/rustc_data_structures/src/sync/vec.rs
@@ -43,37 +43,23 @@ impl<I: Idx, T: Copy> AppendOnlyIndexVec<I, T> {
 
 #[derive(Default)]
 pub struct AppendOnlyVec<T: Copy> {
-    #[cfg(not(parallel_compiler))]
-    vec: elsa::vec::FrozenVec<T>,
-    #[cfg(parallel_compiler)]
-    vec: elsa::sync::LockFreeFrozenVec<T>,
+    vec: parking_lot::RwLock<Vec<T>>,
 }
 
 impl<T: Copy> AppendOnlyVec<T> {
     pub fn new() -> Self {
-        Self {
-            #[cfg(not(parallel_compiler))]
-            vec: elsa::vec::FrozenVec::new(),
-            #[cfg(parallel_compiler)]
-            vec: elsa::sync::LockFreeFrozenVec::new(),
-        }
+        Self { vec: Default::default() }
     }
 
     pub fn push(&self, val: T) -> usize {
-        #[cfg(not(parallel_compiler))]
-        let i = self.vec.len();
-        #[cfg(not(parallel_compiler))]
-        self.vec.push(val);
-        #[cfg(parallel_compiler)]
-        let i = self.vec.push(val);
-        i
+        let mut v = self.vec.write();
+        let n = v.len();
+        v.push(val);
+        n
     }
 
     pub fn get(&self, i: usize) -> Option<T> {
-        #[cfg(not(parallel_compiler))]
-        return self.vec.get_copy(i);
-        #[cfg(parallel_compiler)]
-        return self.vec.get(i);
+        self.vec.read().get(i).copied()
     }
 
     pub fn iter_enumerated(&self) -> impl Iterator<Item = (usize, T)> + '_ {