Pre-intern name when searching module children

This avoids a good deal of work, since each module child can now just be
compared via u32 comparison, rather than fetching the raw &str
(requiring locking and indexing into the interner) and then comparing
the two strings (also relatively expensive).

Author: Mark-Simulacrum

src/tools/miri/src/helpers.rs

@@ -38,9 +38,10 @@ fn try_resolve_did(tcx: TyCtxt<'_>, path: &[&str], namespace: Option<Namespace>)
         item: DefId,
         name: &'a str,
     ) -> impl Iterator<Item = DefId> + 'a {
+        let name = Symbol::intern(name);
         tcx.module_children(item)
             .iter()
-            .filter(move |item| item.ident.name.as_str() == name)
+            .filter(move |item| item.ident.name == name)
             .map(move |item| item.res.def_id())
     }