Only call generics_of query in should_encode_mir when necessary

Author: bjorn3

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1113,11 +1113,10 @@ fn should_encode_mir(
         DefKind::SyntheticCoroutineBody => (false, true),
         // Full-fledged functions + closures
         DefKind::AssocFn | DefKind::Fn | DefKind::Closure => {
-            let generics = tcx.generics_of(def_id);
             let opt = tcx.sess.opts.unstable_opts.always_encode_mir
                 || (tcx.sess.opts.output_types.should_codegen()
                     && reachable_set.contains(&def_id)
-                    && (generics.requires_monomorphization(tcx)
+                    && (tcx.generics_of(def_id).requires_monomorphization(tcx)
                         || tcx.cross_crate_inlinable(def_id)));
             // The function has a `const` modifier or is in a `const trait`.
             let is_const_fn = tcx.is_const_fn(def_id.to_def_id());