Avoid some query invocations, they are unnecessary and cause performa…

…nce regressions

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -11,6 +11,7 @@ use rustc_hir::lang_items::LangItem;
 use rustc_hir::ItemKind;
 use rustc_infer::infer::outlives::env::OutlivesEnvironment;
 use rustc_infer::infer::{self, InferCtxt, TyCtxtInferExt};
+use rustc_middle::mir::interpret::GlobalId;
 use rustc_middle::query::Providers;
 use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::trait_def::TraitSpecializationKind;
@@ -294,8 +295,13 @@ fn check_item<'tcx>(tcx: TyCtxt<'tcx>, item: &'tcx hir::Item<'tcx>) -> Result<()
             tcx.ensure().eval_static_initializer(def_id);
             check_item_type(tcx, def_id, ty.span, UnsizedHandling::Forbid)
         }
-        hir::ItemKind::Const(ty, ..) => {
-            tcx.ensure().const_eval_poly(def_id.into());
+        hir::ItemKind::Const(ty, ast_generics, _) => {
+            if ast_generics.params.is_empty() {
+                let instance = ty::Instance::new(def_id.into(), ty::GenericArgs::empty());
+                let cid = GlobalId { instance, promoted: None };
+                let param_env = ty::ParamEnv::reveal_all();
+                tcx.ensure().eval_to_const_value_raw(param_env.and(cid));
+            }
             check_item_type(tcx, def_id, ty.span, UnsizedHandling::Forbid)
         }
         hir::ItemKind::Struct(_, ast_generics) => {