try using SsoHashMap instead

Author: lcnr

compiler/rustc_type_ir/src/search_graph/mod.rs

@@ -20,6 +20,7 @@ use std::marker::PhantomData;
 use std::{iter, mem};
 
 use derive_where::derive_where;
+use rustc_data_structures::sso::SsoHashMap;
 #[cfg(feature = "nightly")]
 use rustc_macros::{Decodable_NoContext, Encodable_NoContext, HashStable_NoContext};
 use rustc_type_ir::data_structures::HashMap;
@@ -229,7 +230,7 @@ impl Usages {
 
 #[derive(Debug, Default)]
 pub struct CandidateUsages {
-    usages: HashMap<StackDepth, Usages>,
+    usages: SsoHashMap<StackDepth, Usages>,
 }
 impl CandidateUsages {
     pub fn add_usages(&mut self, mut other: CandidateUsages) {