From 76452956e4ee3be89a9da69cccadfb980b075049 Mon Sep 17 00:00:00 2001
From: Jonas Schievink <jonasschievink@gmail.com>
Date: Fri, 2 Apr 2021 18:11:08 +0200
Subject: Split `Intern::drop` into hot and cold path

---
 crates/hir_def/src/intern.rs | 39 +++++++++++++++++++++++----------------
 1 file changed, 23 insertions(+), 16 deletions(-)

(limited to 'crates/hir_def/src')

diff --git a/crates/hir_def/src/intern.rs b/crates/hir_def/src/intern.rs
index 18c8ab246..785d9e3c6 100644
--- a/crates/hir_def/src/intern.rs
+++ b/crates/hir_def/src/intern.rs
@@ -53,31 +53,38 @@ impl<T: Internable> Interned<T> {
 }
 
 impl<T: Internable + ?Sized> Drop for Interned<T> {
+    #[inline]
     fn drop(&mut self) {
         // When the last `Ref` is dropped, remove the object from the global map.
         if Arc::strong_count(&self.arc) == 2 {
             // Only `self` and the global map point to the object.
 
-            let storage = T::storage().get();
-            let shard_idx = storage.determine_map(&self.arc);
-            let shard = &storage.shards()[shard_idx];
-            let mut shard = shard.write();
+            self.drop_slow();
+        }
+    }
+}
+
+impl<T: Internable + ?Sized> Interned<T> {
+    #[cold]
+    fn drop_slow(&mut self) {
+        let storage = T::storage().get();
+        let shard_idx = storage.determine_map(&self.arc);
+        let shard = &storage.shards()[shard_idx];
+        let mut shard = shard.write();
 
-            // FIXME: avoid double lookup
-            let (arc, _) =
-                shard.get_key_value(&self.arc).expect("interned value removed prematurely");
+        // FIXME: avoid double lookup
+        let (arc, _) = shard.get_key_value(&self.arc).expect("interned value removed prematurely");
 
-            if Arc::strong_count(arc) != 2 {
-                // Another thread has interned another copy
-                return;
-            }
+        if Arc::strong_count(arc) != 2 {
+            // Another thread has interned another copy
+            return;
+        }
 
-            shard.remove(&self.arc);
+        shard.remove(&self.arc);
 
-            // Shrink the backing storage if the shard is less than 50% occupied.
-            if shard.len() * 2 < shard.capacity() {
-                shard.shrink_to_fit();
-            }
+        // Shrink the backing storage if the shard is less than 50% occupied.
+        if shard.len() * 2 < shard.capacity() {
+            shard.shrink_to_fit();
         }
     }
 }
-- 
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