add additional TypeFlags fast paths

compiler/rustc_infer/src/infer/canonical/canonicalizer.rs

@@ -497,6 +497,10 @@ impl<'cx, 'tcx> TypeFolder<TyCtxt<'tcx>> for Canonicalizer<'cx, 'tcx> {
     fn fold_predicate(&mut self, p: ty::Predicate<'tcx>) -> ty::Predicate<'tcx> {
         if p.flags().intersects(self.needs_canonical_flags) { p.super_fold_with(self) } else { p }
     }
+
+    fn fold_clauses(&mut self, c: ty::Clauses<'tcx>) -> ty::Clauses<'tcx> {
+        if c.flags().intersects(self.needs_canonical_flags) { c.super_fold_with(self) } else { c }
+    }
 }
 
 impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {

compiler/rustc_infer/src/infer/resolve.rs

@@ -55,6 +55,14 @@ impl<'a, 'tcx> TypeFolder<TyCtxt<'tcx>> for OpportunisticVarResolver<'a, 'tcx> {
             ct.super_fold_with(self)
         }
     }
+
+    fn fold_predicate(&mut self, p: ty::Predicate<'tcx>) -> ty::Predicate<'tcx> {
+        if !p.has_non_region_infer() { p } else { p.super_fold_with(self) }
+    }
+
+    fn fold_clauses(&mut self, c: ty::Clauses<'tcx>) -> ty::Clauses<'tcx> {
+        if !c.has_non_region_infer() { c } else { c.super_fold_with(self) }
+    }
 }
 
 /// The opportunistic region resolver opportunistically resolves regions