Memoize block_item_tree_query

Author: Veykril

crates/hir-def/src/db.rs

@@ -83,9 +83,6 @@ pub trait DefDatabase: InternDatabase + ExpandDatabase + Upcast<dyn ExpandDataba
     fn file_item_tree(&self, file_id: HirFileId) -> Arc<ItemTree>;
 
     #[salsa::invoke(ItemTree::block_item_tree_query)]
-    // FIXME: Investigate memory usage increase if this were not transparent
-    // Also make sure to `shrink_to_fit` if you do
-    #[salsa::transparent]
     fn block_item_tree_query(&self, block_id: BlockId) -> Arc<ItemTree>;
 
     #[salsa::invoke(crate_def_map_wait)]

crates/hir-def/src/item_tree.rs

@@ -148,7 +148,9 @@ impl ItemTree {
         let block = loc.ast_id.to_node(db.upcast());
 
         let ctx = lower::Ctx::new(db, loc.ast_id.file_id);
-        Arc::new(ctx.lower_block(&block))
+        let mut item_tree = ctx.lower_block(&block);
+        item_tree.shrink_to_fit();
+        Arc::new(item_tree)
     }
 
     /// Returns an iterator over all items located at the top level of the `HirFileId` this
@@ -383,7 +385,7 @@ impl TreeId {
 
     pub(crate) fn item_tree(&self, db: &dyn DefDatabase) -> Arc<ItemTree> {
         match self.block {
-            Some(block) => ItemTree::block_item_tree_query(db, block),
+            Some(block) => db.block_item_tree_query(block),
             None => db.file_item_tree(self.file),
         }
     }