Auto merge of #108020 - nnethercote:opt-mk_region, r=compiler-errors

Optimize `mk_region`

PR #107869 avoiding some interning under `mk_ty` by special-casing `Ty` variants with simple (integer) bodies. This PR does something similar for regions.

r? `@compiler-errors`

40 files changed, 254 insertions, 186 deletions

diff --git a/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs b/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs
index 1550958ab8e..d51cc652bfd 100644
--- a/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs
@@ -180,20 +180,20 @@ trait TypeOpInfo<'tcx> {
             return;
         };
 
-        let placeholder_region = tcx.mk_region(ty::RePlaceholder(ty::Placeholder {
+        let placeholder_region = tcx.mk_re_placeholder(ty::Placeholder {
             name: placeholder.name,
             universe: adjusted_universe.into(),
-        }));
+        });
 
         let error_region =
             if let RegionElement::PlaceholderRegion(error_placeholder) = error_element {
                 let adjusted_universe =
                     error_placeholder.universe.as_u32().checked_sub(base_universe.as_u32());
                 adjusted_universe.map(|adjusted| {
-                    tcx.mk_region(ty::RePlaceholder(ty::Placeholder {
+                    tcx.mk_re_placeholder(ty::Placeholder {
                         name: error_placeholder.name,
                         universe: adjusted.into(),
-                    }))
+                    })
                 })
             } else {
                 None
@@ -390,7 +390,7 @@ fn try_extract_error_from_fulfill_cx<'tcx>(
         error_region,
         &region_constraints,
         |vid| ocx.infcx.region_var_origin(vid),
-        |vid| ocx.infcx.universe_of_region(ocx.infcx.tcx.mk_region(ty::ReVar(vid))),
+        |vid| ocx.infcx.universe_of_region(ocx.infcx.tcx.mk_re_var(vid)),
     )
 }
 
@@ -411,7 +411,7 @@ fn try_extract_error_from_region_constraints<'tcx>(
                 }
                 // FIXME: Should this check the universe of the var?
                 Constraint::VarSubReg(vid, sup) if sup == placeholder_region => {
-                    Some((infcx.tcx.mk_region(ty::ReVar(vid)), cause.clone()))
+                    Some((infcx.tcx.mk_re_var(vid), cause.clone()))
                 }
                 _ => None,
             }
diff --git a/compiler/rustc_borrowck/src/region_infer/mod.rs b/compiler/rustc_borrowck/src/region_infer/mod.rs
index f2693bded59..83fdb6066c6 100644
--- a/compiler/rustc_borrowck/src/region_infer/mod.rs
+++ b/compiler/rustc_borrowck/src/region_infer/mod.rs
@@ -1297,7 +1297,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             let vid = self.to_region_vid(r);
             let scc = self.constraint_sccs.scc(vid);
             let repr = self.scc_representatives[scc];
-            tcx.mk_region(ty::ReVar(repr))
+            tcx.mk_re_var(repr)
         })
     }
 
@@ -1719,7 +1719,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             }
 
             // If not, report an error.
-            let member_region = infcx.tcx.mk_region(ty::ReVar(member_region_vid));
+            let member_region = infcx.tcx.mk_re_var(member_region_vid);
             errors_buffer.push(RegionErrorKind::UnexpectedHiddenRegion {
                 span: m_c.definition_span,
                 hidden_ty: m_c.hidden_ty,
diff --git a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
index c7b22d5f2e6..bb42301828d 100644
--- a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
+++ b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
@@ -91,7 +91,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                     }
                     None => {
                         subst_regions.push(vid);
-                        infcx.tcx.re_error_with_message(
+                        infcx.tcx.mk_re_error_with_message(
                             concrete_type.span,
                             "opaque type with non-universal region substs",
                         )
diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs
index 5b7adae66ac..7a05fde47fc 100644
--- a/compiler/rustc_borrowck/src/type_check/mod.rs
+++ b/compiler/rustc_borrowck/src/type_check/mod.rs
@@ -137,7 +137,7 @@ pub(crate) fn type_check<'mir, 'tcx>(
     upvars: &[Upvar<'tcx>],
     use_polonius: bool,
 ) -> MirTypeckResults<'tcx> {
-    let implicit_region_bound = infcx.tcx.mk_region(ty::ReVar(universal_regions.fr_fn_body));
+    let implicit_region_bound = infcx.tcx.mk_re_var(universal_regions.fr_fn_body);
     let mut constraints = MirTypeckRegionConstraints {
         placeholder_indices: PlaceholderIndices::default(),
         placeholder_index_to_region: IndexVec::default(),
diff --git a/compiler/rustc_borrowck/src/universal_regions.rs b/compiler/rustc_borrowck/src/universal_regions.rs
index 56930c89b2c..3f254a6b7b6 100644
--- a/compiler/rustc_borrowck/src/universal_regions.rs
+++ b/compiler/rustc_borrowck/src/universal_regions.rs
@@ -480,10 +480,8 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
                     LangItem::VaList,
                     Some(self.infcx.tcx.def_span(self.mir_def.did)),
                 );
-                let region = self
-                    .infcx
-                    .tcx
-                    .mk_region(ty::ReVar(self.infcx.next_nll_region_var(FR).to_region_vid()));
+                let region =
+                    self.infcx.tcx.mk_re_var(self.infcx.next_nll_region_var(FR).to_region_vid());
                 let va_list_ty = self
                     .infcx
                     .tcx
@@ -636,7 +634,7 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
                     var: ty::BoundVar::from_usize(bound_vars.len() - 1),
                     kind: ty::BrEnv,
                 };
-                let env_region = ty::ReLateBound(ty::INNERMOST, br);
+                let env_region = tcx.mk_re_late_bound(ty::INNERMOST, br);
                 let closure_ty = tcx.closure_env_ty(def_id, substs, env_region).unwrap();
 
                 // The "inputs" of the closure in the
@@ -748,10 +746,7 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
     {
         let (value, _map) = self.tcx.replace_late_bound_regions(value, |br| {
             debug!(?br);
-            let liberated_region = self.tcx.mk_region(ty::ReFree(ty::FreeRegion {
-                scope: all_outlive_scope.to_def_id(),
-                bound_region: br.kind,
-            }));
+            let liberated_region = self.tcx.mk_re_free(all_outlive_scope.to_def_id(), br.kind);
             let region_vid = self.next_nll_region_var(origin);
             indices.insert_late_bound_region(liberated_region, region_vid.to_region_vid());
             debug!(?liberated_region, ?region_vid);
@@ -843,7 +838,7 @@ impl<'tcx> UniversalRegionIndices<'tcx> {
     where
         T: TypeFoldable<'tcx>,
     {
-        tcx.fold_regions(value, |region, _| tcx.mk_region(ty::ReVar(self.to_region_vid(region))))
+        tcx.fold_regions(value, |region, _| tcx.mk_re_var(self.to_region_vid(region)))
     }
 }
 
@@ -883,8 +878,7 @@ fn for_each_late_bound_region_in_item<'tcx>(
 
     for bound_var in tcx.late_bound_vars(tcx.hir().local_def_id_to_hir_id(mir_def_id)) {
         let ty::BoundVariableKind::Region(bound_region) = bound_var else { continue; };
-        let liberated_region = tcx
-            .mk_region(ty::ReFree(ty::FreeRegion { scope: mir_def_id.to_def_id(), bound_region }));
+        let liberated_region = tcx.mk_re_free(mir_def_id.to_def_id(), bound_region);
         f(liberated_region);
     }
 }
diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index 46dc4141e66..e5c176f19ea 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -234,7 +234,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                     var: ty::BoundVar::from_u32(index),
                     kind: ty::BrNamed(def_id, name),
                 };
-                tcx.mk_region(ty::ReLateBound(debruijn, br))
+                tcx.mk_re_late_bound(debruijn, br)
             }
 
             Some(rl::Region::EarlyBound(def_id)) => {
@@ -242,15 +242,12 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 let item_def_id = tcx.hir().ty_param_owner(def_id.expect_local());
                 let generics = tcx.generics_of(item_def_id);
                 let index = generics.param_def_id_to_index[&def_id];
-                tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion { def_id, index, name }))
+                tcx.mk_re_early_bound(ty::EarlyBoundRegion { def_id, index, name })
             }
 
             Some(rl::Region::Free(scope, id)) => {
                 let name = lifetime_name(id.expect_local());
-                tcx.mk_region(ty::ReFree(ty::FreeRegion {
-                    scope,
-                    bound_region: ty::BrNamed(id, name),
-                }))
+                tcx.mk_re_free(scope, ty::BrNamed(id, name))
 
                 // (*) -- not late-bound, won't change
             }
@@ -263,7 +260,10 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                     // elision. `resolve_lifetime` should have
                     // reported an error in this case -- but if
                     // not, let's error out.
-                    tcx.re_error_with_message(lifetime.ident.span, "unelided lifetime in signature")
+                    tcx.mk_re_error_with_message(
+                        lifetime.ident.span,
+                        "unelided lifetime in signature",
+                    )
                 })
             }
         }
@@ -477,7 +477,10 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                             debug!(?param, "unelided lifetime in signature");
 
                             // This indicates an illegal lifetime in a non-assoc-trait position
-                            tcx.re_error_with_message(self.span, "unelided lifetime in signature")
+                            tcx.mk_re_error_with_message(
+                                self.span,
+                                "unelided lifetime in signature",
+                            )
                         })
                         .into(),
                     GenericParamDefKind::Type { has_default, .. } => {
@@ -1622,7 +1625,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                         } else {
                             err.emit()
                         };
-                        tcx.re_error(e)
+                        tcx.mk_re_error(e)
                     })
                 }
             })
diff --git a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
index 6b0eade2d32..94e1fcebccd 100644
--- a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
+++ b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
@@ -464,14 +464,10 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for RemapLateBound<'_, 'tcx> {
 
     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
         if let ty::ReFree(fr) = *r {
-            self.tcx.mk_region(ty::ReFree(ty::FreeRegion {
-                bound_region: self
-                    .mapping
-                    .get(&fr.bound_region)
-                    .copied()
-                    .unwrap_or(fr.bound_region),
-                ..fr
-            }))
+            self.tcx.mk_re_free(
+                fr.scope,
+                self.mapping.get(&fr.bound_region).copied().unwrap_or(fr.bound_region),
+            )
         } else {
             r
         }
@@ -777,13 +773,13 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>(
                     }
                     let Some(ty::ReEarlyBound(e)) = map.get(&region.into()).map(|r| r.expect_region().kind())
                     else {
-                        return tcx.re_error_with_message(return_span, "expected ReFree to map to ReEarlyBound")
+                        return tcx.mk_re_error_with_message(return_span, "expected ReFree to map to ReEarlyBound")
                     };
-                    tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
+                    tcx.mk_re_early_bound(ty::EarlyBoundRegion {
                         def_id: e.def_id,
                         name: e.name,
                         index: (e.index as usize - num_trait_substs + num_impl_substs) as u32,
-                    }))
+                    })
                 });
                 debug!(%ty);
                 collected_tys.insert(def_id, ty);
@@ -1920,10 +1916,10 @@ pub(super) fn check_type_bounds<'tcx>(
             let kind = ty::BoundRegionKind::BrNamed(param.def_id, param.name);
             let bound_var = ty::BoundVariableKind::Region(kind);
             bound_vars.push(bound_var);
-            tcx.mk_region(ty::ReLateBound(
+            tcx.mk_re_late_bound(
                 ty::INNERMOST,
                 ty::BoundRegion { var: ty::BoundVar::from_usize(bound_vars.len() - 1), kind },
-            ))
+            )
             .into()
         }
         GenericParamDefKind::Const { .. } => {
diff --git a/compiler/rustc_hir_analysis/src/check/intrinsic.rs b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
index 955cacf03b1..4fc37856dfc 100644
--- a/compiler/rustc_hir_analysis/src/check/intrinsic.rs
+++ b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
@@ -149,14 +149,14 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
     );
     let mk_va_list_ty = |mutbl| {
         tcx.lang_items().va_list().map(|did| {
-            let region = tcx.mk_region(ty::ReLateBound(
+            let region = tcx.mk_re_late_bound(
                 ty::INNERMOST,
                 ty::BoundRegion { var: ty::BoundVar::from_u32(0), kind: ty::BrAnon(0, None) },
-            ));
-            let env_region = tcx.mk_region(ty::ReLateBound(
+            );
+            let env_region = tcx.mk_re_late_bound(
                 ty::INNERMOST,
                 ty::BoundRegion { var: ty::BoundVar::from_u32(1), kind: ty::BrEnv },
-            ));
+            );
             let va_list_ty = tcx.bound_type_of(did).subst(tcx, &[region.into()]);
             (tcx.mk_ref(env_region, ty::TypeAndMut { ty: va_list_ty, mutbl }), va_list_ty)
         })
@@ -377,9 +377,7 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
                     ty::BoundRegion { var: ty::BoundVar::from_u32(0), kind: ty::BrAnon(0, None) };
                 (
                     1,
-                    vec![
-                        tcx.mk_imm_ref(tcx.mk_region(ty::ReLateBound(ty::INNERMOST, br)), param(0)),
-                    ],
+                    vec![tcx.mk_imm_ref(tcx.mk_re_late_bound(ty::INNERMOST, br), param(0))],
                     tcx.mk_projection(discriminant_def_id, tcx.mk_substs([param(0).into()].iter())),
                 )
             }
@@ -430,8 +428,7 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
             sym::raw_eq => {
                 let br =
                     ty::BoundRegion { var: ty::BoundVar::from_u32(0), kind: ty::BrAnon(0, None) };
-                let param_ty =
-                    tcx.mk_imm_ref(tcx.mk_region(ty::ReLateBound(ty::INNERMOST, br)), param(0));
+                let param_ty = tcx.mk_imm_ref(tcx.mk_re_late_bound(ty::INNERMOST, br), param(0));
                 (1, vec![param_ty; 2], tcx.types.bool)
             }
 
diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
index c64d507f828..ee39fde1dcb 100644
--- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs
+++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -607,12 +607,11 @@ fn gather_gat_bounds<'tcx, T: TypeFoldable<'tcx>>(
                 // Same for the region. In our example, 'a corresponds
                 // to the 'me parameter.
                 let region_param = gat_generics.param_at(*region_a_idx, tcx);
-                let region_param =
-                    tcx.mk_region(ty::RegionKind::ReEarlyBound(ty::EarlyBoundRegion {
-                        def_id: region_param.def_id,
-                        index: region_param.index,
-                        name: region_param.name,
-                    }));
+                let region_param = tcx.mk_re_early_bound(ty::EarlyBoundRegion {
+                    def_id: region_param.def_id,
+                    index: region_param.index,
+                    name: region_param.name,
+                });
                 // The predicate we expect to see. (In our example,
                 // `Self: 'me`.)
                 let clause = ty::PredicateKind::Clause(ty::Clause::TypeOutlives(
@@ -645,20 +644,18 @@ fn gather_gat_bounds<'tcx, T: TypeFoldable<'tcx>>(
                 debug!("required clause: {region_a} must outlive {region_b}");
                 // Translate into the generic parameters of the GAT.
                 let region_a_param = gat_generics.param_at(*region_a_idx, tcx);
-                let region_a_param =
-                    tcx.mk_region(ty::RegionKind::ReEarlyBound(ty::EarlyBoundRegion {
-                        def_id: region_a_param.def_id,
-                        index: region_a_param.index,
-                        name: region_a_param.name,
-                    }));
+                let region_a_param = tcx.mk_re_early_bound(ty::EarlyBoundRegion {
+                    def_id: region_a_param.def_id,
+                    index: region_a_param.index,
+                    name: region_a_param.name,
+                });
                 // Same for the region.
                 let region_b_param = gat_generics.param_at(*region_b_idx, tcx);
-                let region_b_param =
-                    tcx.mk_region(ty::RegionKind::ReEarlyBound(ty::EarlyBoundRegion {
-                        def_id: region_b_param.def_id,
-                        index: region_b_param.index,
-                        name: region_b_param.name,
-                    }));
+                let region_b_param = tcx.mk_re_early_bound(ty::EarlyBoundRegion {
+                    def_id: region_b_param.def_id,
+                    index: region_b_param.index,
+                    name: region_b_param.name,
+                });
                 // The predicate we expect to see.
                 let clause = ty::PredicateKind::Clause(ty::Clause::RegionOutlives(
                     ty::OutlivesPredicate(region_a_param, region_b_param),
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
index 9f33d84ab52..456c5bc99b7 100644
--- a/compiler/rustc_hir_analysis/src/collect.rs
+++ b/compiler/rustc_hir_analysis/src/collect.rs
@@ -458,13 +458,11 @@ impl<'tcx> AstConv<'tcx> for ItemCtxt<'tcx> {
                                         self.tcx.replace_late_bound_regions_uncached(
                                             poly_trait_ref,
                                             |_| {
-                                                self.tcx.mk_region(ty::ReEarlyBound(
-                                                    ty::EarlyBoundRegion {
-                                                        def_id: item_def_id,
-                                                        index: 0,
-                                                        name: Symbol::intern(&lt_name),
-                                                    },
-                                                ))
+                                                self.tcx.mk_re_early_bound(ty::EarlyBoundRegion {
+                                                    def_id: item_def_id,
+                                                    index: 0,
+                                                    name: Symbol::intern(&lt_name),
+                                                })
                                             }
                                         ),
                                     ),
diff --git a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
index d0d67ae9257..5ac9003556d 100644
--- a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
@@ -284,11 +284,11 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericP
 
             let Some(dup_index) = generics.param_def_id_to_index(tcx, dup_def) else { bug!() };
 
-            let dup_region = tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
+            let dup_region = tcx.mk_re_early_bound(ty::EarlyBoundRegion {
                 def_id: dup_def,
                 index: dup_index,
                 name: duplicate.name.ident().name,
-            }));
+            });
             predicates.push((
                 ty::Binder::dummy(ty::PredicateKind::Clause(ty::Clause::RegionOutlives(
                     ty::OutlivesPredicate(orig_region, dup_region),
diff --git a/compiler/rustc_hir_typeck/src/demand.rs b/compiler/rustc_hir_typeck/src/demand.rs
index 76e87a9e566..de7819e3c6a 100644
--- a/compiler/rustc_hir_typeck/src/demand.rs
+++ b/compiler/rustc_hir_typeck/src/demand.rs
@@ -1269,10 +1269,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 // ```
                 let ref_ty = match mutability {
                     hir::Mutability::Mut => {
-                        self.tcx.mk_mut_ref(self.tcx.mk_region(ty::ReStatic), checked_ty)
+                        self.tcx.mk_mut_ref(self.tcx.lifetimes.re_static, checked_ty)
                     }
                     hir::Mutability::Not => {
-                        self.tcx.mk_imm_ref(self.tcx.mk_region(ty::ReStatic), checked_ty)
+                        self.tcx.mk_imm_ref(self.tcx.lifetimes.re_static, checked_ty)
                     }
                 };
                 if self.can_coerce(ref_ty, expected) {
diff --git a/compiler/rustc_hir_typeck/src/generator_interior/mod.rs b/compiler/rustc_hir_typeck/src/generator_interior/mod.rs
index 29ed9a24ecf..0e9e698e829 100644
--- a/compiler/rustc_hir_typeck/src/generator_interior/mod.rs
+++ b/compiler/rustc_hir_typeck/src/generator_interior/mod.rs
@@ -271,7 +271,7 @@ pub fn resolve_interior<'a, 'tcx>(
                     },
                     _ => mk_bound_region(None),
                 };
-                let r = fcx.tcx.mk_region(ty::ReLateBound(current_depth, br));
+                let r = fcx.tcx.mk_re_late_bound(current_depth, br);
                 r
             });
             if captured_tys.insert(ty) {
@@ -302,7 +302,7 @@ pub fn resolve_interior<'a, 'tcx>(
                     let var = ty::BoundVar::from_usize(bound_vars.len());
                     bound_vars.push(ty::BoundVariableKind::Region(kind));
                     counter += 1;
-                    fcx.tcx.mk_region(ty::ReLateBound(ty::INNERMOST, ty::BoundRegion { var, kind }))
+                    fcx.tcx.mk_re_late_bound(ty::INNERMOST, ty::BoundRegion { var, kind })
                 },
                 types: &mut |b| bug!("unexpected bound ty in binder: {b:?}"),
                 consts: &mut |b, ty| bug!("unexpected bound ct in binder: {b:?} {ty}"),
@@ -364,7 +364,7 @@ impl<'a, 'tcx> Visitor<'tcx> for InteriorVisitor<'a, 'tcx> {
                             let ty = tcx.mk_ref(
                                 // Use `ReErased` as `resolve_interior` is going to replace all the
                                 // regions anyway.
-                                tcx.mk_region(ty::ReErased),
+                                tcx.lifetimes.re_erased,
                                 ty::TypeAndMut { ty, mutbl: hir::Mutability::Not },
                             );
                             self.interior_visitor.record(
diff --git a/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs b/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs
index 6bfdeda3a24..2b33d31994f 100644
--- a/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs
+++ b/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs
@@ -363,7 +363,7 @@ impl<'cx, 'tcx> TypeFolder<TyCtxt<'tcx>> for Canonicalizer<'cx, 'tcx> {
                      opportunistically resolved to {:?}",
                     vid, resolved_vid
                 );
-                let r = self.tcx.reuse_or_mk_region(r, ty::ReVar(resolved_vid));
+                let r = self.tcx.mk_re_var(resolved_vid);
                 self.canonicalize_mode.canonicalize_free_region(self, r)
             }
 
@@ -737,8 +737,7 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
     ) -> ty::Region<'tcx> {
         let var = self.canonical_var(info, r.into());
         let br = ty::BoundRegion { var, kind: ty::BrAnon(var.as_u32(), None) };
-        let region = ty::ReLateBound(self.binder_index, br);
-        self.interner().mk_region(region)
+        self.interner().mk_re_late_bound(self.binder_index, br)
     }
 
     /// Given a type variable `ty_var` of the given kind, first check
diff --git a/compiler/rustc_infer/src/infer/canonical/mod.rs b/compiler/rustc_infer/src/infer/canonical/mod.rs
index d5cb3fb2498..4552256545b 100644
--- a/compiler/rustc_infer/src/infer/canonical/mod.rs
+++ b/compiler/rustc_infer/src/infer/canonical/mod.rs
@@ -137,7 +137,7 @@ impl<'tcx> InferCtxt<'tcx> {
             CanonicalVarKind::PlaceholderRegion(ty::PlaceholderRegion { universe, name }) => {
                 let universe_mapped = universe_map(universe);
                 let placeholder_mapped = ty::PlaceholderRegion { universe: universe_mapped, name };
-                self.tcx.mk_region(ty::RePlaceholder(placeholder_mapped)).into()
+                self.tcx.mk_re_placeholder(placeholder_mapped).into()
             }
 
             CanonicalVarKind::Const(ui, ty) => self
diff --git a/compiler/rustc_infer/src/infer/canonical/query_response.rs b/compiler/rustc_infer/src/infer/canonical/query_response.rs
index 0c97217bd6a..b9cb9732ca3 100644
--- a/compiler/rustc_infer/src/infer/canonical/query_response.rs
+++ b/compiler/rustc_infer/src/infer/canonical/query_response.rs
@@ -642,15 +642,14 @@ pub fn make_query_region_constraints<'tcx>(
             let constraint = match *k {
                 // Swap regions because we are going from sub (<=) to outlives
                 // (>=).
-                Constraint::VarSubVar(v1, v2) => ty::OutlivesPredicate(
-                    tcx.mk_region(ty::ReVar(v2)).into(),
-                    tcx.mk_region(ty::ReVar(v1)),
-                ),
+                Constraint::VarSubVar(v1, v2) => {
+                    ty::OutlivesPredicate(tcx.mk_re_var(v2).into(), tcx.mk_re_var(v1))
+                }
                 Constraint::VarSubReg(v1, r2) => {
-                    ty::OutlivesPredicate(r2.into(), tcx.mk_region(ty::ReVar(v1)))
+                    ty::OutlivesPredicate(r2.into(), tcx.mk_re_var(v1))
                 }
                 Constraint::RegSubVar(r1, v2) => {
-                    ty::OutlivesPredicate(tcx.mk_region(ty::ReVar(v2)).into(), r1)
+                    ty::OutlivesPredicate(tcx.mk_re_var(v2).into(), r1)
                 }
                 Constraint::RegSubReg(r1, r2) => ty::OutlivesPredicate(r2.into(), r1),
             };
@@ -690,7 +689,7 @@ impl<'tcx> TypeRelatingDelegate<'tcx> for QueryTypeRelatingDelegate<'_, 'tcx> {
     }
 
     fn next_placeholder_region(&mut self, placeholder: ty::PlaceholderRegion) -> ty::Region<'tcx> {
-        self.infcx.tcx.mk_region(ty::RePlaceholder(placeholder))
+        self.infcx.tcx.mk_re_placeholder(placeholder)
     }
 
     fn generalize_existential(&mut self, universe: ty::UniverseIndex) -> ty::Region<'tcx> {
diff --git a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/placeholder_error.rs b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/placeholder_error.rs
index 99431567eda..c1ea0a0d95e 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/placeholder_error.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/placeholder_error.rs
@@ -14,7 +14,7 @@ use rustc_hir::def_id::DefId;
 use rustc_middle::ty::error::ExpectedFound;
 use rustc_middle::ty::print::{FmtPrinter, Print, RegionHighlightMode};
 use rustc_middle::ty::subst::SubstsRef;
-use rustc_middle::ty::{self, RePlaceholder, ReVar, Region, TyCtxt};
+use rustc_middle::ty::{self, RePlaceholder, Region, TyCtxt};
 
 use std::fmt;
 
@@ -79,7 +79,7 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
                 sup_placeholder @ Region(Interned(RePlaceholder(_), _)),
                 _,
             )) => self.try_report_trait_placeholder_mismatch(
-                Some(self.tcx().mk_region(ReVar(*vid))),
+                Some(self.tcx().mk_re_var(*vid)),
                 cause,
                 Some(*sub_placeholder),
                 Some(*sup_placeholder),
@@ -95,7 +95,7 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
                 _,
                 _,
             )) => self.try_report_trait_placeholder_mismatch(
-                Some(self.tcx().mk_region(ReVar(*vid))),
+                Some(self.tcx().mk_re_var(*vid)),
                 cause,
                 Some(*sub_placeholder),
                 None,
@@ -111,7 +111,7 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
                 sup_placeholder @ Region(Interned(RePlaceholder(_), _)),
                 _,
             )) => self.try_report_trait_placeholder_mismatch(
-                Some(self.tcx().mk_region(ReVar(*vid))),
+                Some(self.tcx().mk_re_var(*vid)),
                 cause,
                 None,
                 Some(*sup_placeholder),
@@ -127,7 +127,7 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
                 sup_placeholder @ Region(Interned(RePlaceholder(_), _)),
                 _,
             )) => self.try_report_trait_placeholder_mismatch(
-                Some(self.tcx().mk_region(ReVar(*vid))),
+                Some(self.tcx().mk_re_var(*vid)),
                 cause,
                 None,
                 Some(*sup_placeholder),
@@ -141,7 +141,7 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
                 SubregionOrigin::Subtype(box TypeTrace { cause, values }),
                 sup_placeholder @ Region(Interned(RePlaceholder(_), _)),
             )) => self.try_report_trait_placeholder_mismatch(
-                Some(self.tcx().mk_region(ReVar(*vid))),
+                Some(self.tcx().mk_re_var(*vid)),
                 cause,
                 None,
                 Some(*sup_placeholder),
diff --git a/compiler/rustc_infer/src/infer/higher_ranked/mod.rs b/compiler/rustc_infer/src/infer/higher_ranked/mod.rs
index 39940f4592d..82a1bb1fd16 100644
--- a/compiler/rustc_infer/src/infer/higher_ranked/mod.rs
+++ b/compiler/rustc_infer/src/infer/higher_ranked/mod.rs
@@ -82,10 +82,10 @@ impl<'tcx> InferCtxt<'tcx> {
 
         let delegate = FnMutDelegate {
             regions: &mut |br: ty::BoundRegion| {
-                self.tcx.mk_region(ty::RePlaceholder(ty::PlaceholderRegion {
+                self.tcx.mk_re_placeholder(ty::PlaceholderRegion {
                     universe: next_universe,
                     name: br.kind,
-                }))
+                })
             },
             types: &mut |bound_ty: ty::BoundTy| {
                 self.tcx.mk_placeholder(ty::PlaceholderType {
diff --git a/compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs b/compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs
index 4a2210bdb68..ac203c4eb0b 100644
--- a/compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs
+++ b/compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs
@@ -382,7 +382,7 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
                     // name the placeholder, then the placeholder is
                     // larger; otherwise, the only ancestor is `'static`.
                     Err(placeholder) if empty_ui.can_name(placeholder.universe) => {
-                        self.tcx().mk_region(RePlaceholder(placeholder))
+                        self.tcx().mk_re_placeholder(placeholder)
                     }
                     Err(_) => self.tcx().lifetimes.re_static,
                 };
@@ -1046,7 +1046,7 @@ impl<'tcx> LexicalRegionResolutions<'tcx> {
             ty::ReVar(rid) => match self.values[rid] {
                 VarValue::Empty(_) => r,
                 VarValue::Value(r) => r,
-                VarValue::ErrorValue => tcx.re_error_misc(),
+                VarValue::ErrorValue => tcx.mk_re_error_misc(),
             },
             _ => r,
         };
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index 17e734f0700..bb734ccb20e 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -1093,7 +1093,7 @@ impl<'tcx> InferCtxt<'tcx> {
     ) -> ty::Region<'tcx> {
         let region_var =
             self.inner.borrow_mut().unwrap_region_constraints().new_region_var(universe, origin);
-        self.tcx.mk_region(ty::ReVar(region_var))
+        self.tcx.mk_re_var(region_var)
     }
 
     /// Return the universe that the region `r` was created in. For
diff --git a/compiler/rustc_infer/src/infer/region_constraints/leak_check.rs b/compiler/rustc_infer/src/infer/region_constraints/leak_check.rs
index c46edc33ff4..e413b2bb570 100644
--- a/compiler/rustc_infer/src/infer/region_constraints/leak_check.rs
+++ b/compiler/rustc_infer/src/infer/region_constraints/leak_check.rs
@@ -280,7 +280,7 @@ impl<'me, 'tcx> LeakCheck<'me, 'tcx> {
         placeholder1: ty::PlaceholderRegion,
         placeholder2: ty::PlaceholderRegion,
     ) -> TypeError<'tcx> {
-        self.error(placeholder1, self.tcx.mk_region(ty::RePlaceholder(placeholder2)))
+        self.error(placeholder1, self.tcx.mk_re_placeholder(placeholder2))
     }
 
     fn error(
@@ -413,19 +413,19 @@ impl<'tcx> MiniGraph<'tcx> {
         for undo_entry in undo_log {
             match undo_entry {
                 &AddConstraint(Constraint::VarSubVar(a, b)) => {
-                    each_edge(tcx.mk_region(ReVar(a)), tcx.mk_region(ReVar(b)));
+                    each_edge(tcx.mk_re_var(a), tcx.mk_re_var(b));
                 }
                 &AddConstraint(Constraint::RegSubVar(a, b)) => {
-                    each_edge(a, tcx.mk_region(ReVar(b)));
+                    each_edge(a, tcx.mk_re_var(b));
                 }
                 &AddConstraint(Constraint::VarSubReg(a, b)) => {
-                    each_edge(tcx.mk_region(ReVar(a)), b);
+                    each_edge(tcx.mk_re_var(a), b);
                 }
                 &AddConstraint(Constraint::RegSubReg(a, b)) => {
                     each_edge(a, b);
                 }
                 &AddGiven(a, b) => {
-                    each_edge(a, tcx.mk_region(ReVar(b)));
+                    each_edge(a, tcx.mk_re_var(b));
                 }
                 &AddVerify(i) => span_bug!(
                     verifys[i].origin.span(),
diff --git a/compiler/rustc_infer/src/infer/region_constraints/mod.rs b/compiler/rustc_infer/src/infer/region_constraints/mod.rs
index cb24375c7a3..33514eedfc3 100644
--- a/compiler/rustc_infer/src/infer/region_constraints/mod.rs
+++ b/compiler/rustc_infer/src/infer/region_constraints/mod.rs
@@ -651,7 +651,7 @@ impl<'tcx> RegionConstraintCollector<'_, 'tcx> {
                 let unified_region = self.unification_table().probe_value(rid);
                 unified_region.0.unwrap_or_else(|| {
                     let root = self.unification_table().find(rid).vid;
-                    tcx.reuse_or_mk_region(region, ty::ReVar(root))
+                    tcx.mk_re_var(root)
                 })
             }
             _ => region,
@@ -675,7 +675,7 @@ impl<'tcx> RegionConstraintCollector<'_, 'tcx> {
     ) -> Region<'tcx> {
         let vars = TwoRegions { a, b };
         if let Some(&c) = self.combine_map(t).get(&vars) {
-            return tcx.mk_region(ReVar(c));
+            return tcx.mk_re_var(c);
         }
         let a_universe = self.universe(a);
         let b_universe = self.universe(b);
@@ -683,7 +683,7 @@ impl<'tcx> RegionConstraintCollector<'_, 'tcx> {
         let c = self.new_region_var(c_universe, MiscVariable(origin.span()));
         self.combine_map(t).insert(vars, c);
         self.undo_log.push(AddCombination(t, vars));
-        let new_r = tcx.mk_region(ReVar(c));
+        let new_r = tcx.mk_re_var(c);
         for old_r in [a, b] {
             match t {
                 Glb => self.make_subregion(origin.clone(), new_r, old_r),
diff --git a/compiler/rustc_infer/src/infer/resolve.rs b/compiler/rustc_infer/src/infer/resolve.rs
index 008bf1e9c5d..2c246a5787c 100644
--- a/compiler/rustc_infer/src/infer/resolve.rs
+++ b/compiler/rustc_infer/src/infer/resolve.rs
@@ -95,7 +95,7 @@ impl<'a, 'tcx> TypeFolder<TyCtxt<'tcx>> for OpportunisticRegionResolver<'a, 'tcx
                     .borrow_mut()
                     .unwrap_region_constraints()
                     .opportunistic_resolve_var(rid);
-                TypeFolder::interner(self).reuse_or_mk_region(r, ty::ReVar(resolved))
+                TypeFolder::interner(self).mk_re_var(resolved)
             }
             _ => r,
         }
diff --git a/compiler/rustc_middle/src/infer/canonical.rs b/compiler/rustc_middle/src/infer/canonical.rs
index ada516aa032..bb617e692cc 100644
--- a/compiler/rustc_middle/src/infer/canonical.rs
+++ b/compiler/rustc_middle/src/infer/canonical.rs
@@ -353,7 +353,7 @@ impl<'tcx> CanonicalVarValues<'tcx> {
                                 var: ty::BoundVar::from_usize(i),
                                 kind: ty::BrAnon(i as u32, None),
                             };
-                            tcx.mk_region(ty::ReLateBound(ty::INNERMOST, br)).into()
+                            tcx.mk_re_late_bound(ty::INNERMOST, br).into()
                         }
                         CanonicalVarKind::Const(_, ty)
                         | CanonicalVarKind::PlaceholderConst(_, ty) => tcx
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 4aef071cd98..b47996ffba2 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -243,11 +243,20 @@ impl<'tcx> CtxtInterners<'tcx> {
     }
 }
 
+// For these preinterned values, an alternative would be to have
+// variable-length vectors that grow as needed. But that turned out to be
+// slightly more complex and no faster.
+
 const NUM_PREINTERNED_TY_VARS: u32 = 100;
 const NUM_PREINTERNED_FRESH_TYS: u32 = 20;
 const NUM_PREINTERNED_FRESH_INT_TYS: u32 = 3;
 const NUM_PREINTERNED_FRESH_FLOAT_TYS: u32 = 3;
 
+// This number may seem high, but it is reached in all but the smallest crates.
+const NUM_PREINTERNED_RE_VARS: u32 = 500;
+const NUM_PREINTERNED_RE_LATE_BOUNDS_I: u32 = 2;
+const NUM_PREINTERNED_RE_LATE_BOUNDS_V: u32 = 20;
+
 pub struct CommonTypes<'tcx> {
     pub unit: Ty<'tcx>,
     pub bool: Ty<'tcx>,
@@ -295,6 +304,14 @@ pub struct CommonLifetimes<'tcx> {
 
     /// Erased region, used outside of type inference.
     pub re_erased: Region<'tcx>,
+
+    /// Pre-interned `ReVar(ty::RegionVar(n))` for small values of `n`.
+    pub re_vars: Vec<Region<'tcx>>,
+
+    /// Pre-interned values of the form:
+    /// `ReLateBound(DebruijnIndex(i), BoundRegion { var: v, kind: BrAnon(v, None) })
+    /// for small values of `i` and `v`.
+    pub re_late_bounds: Vec<Vec<Region<'tcx>>>,
 }
 
 pub struct CommonConsts<'tcx> {
@@ -358,7 +375,31 @@ impl<'tcx> CommonLifetimes<'tcx> {
             ))
         };
 
-        CommonLifetimes { re_static: mk(ty::ReStatic), re_erased: mk(ty::ReErased) }
+        let re_vars =
+            (0..NUM_PREINTERNED_RE_VARS).map(|n| mk(ty::ReVar(ty::RegionVid::from(n)))).collect();
+
+        let re_late_bounds = (0..NUM_PREINTERNED_RE_LATE_BOUNDS_I)
+            .map(|i| {
+                (0..NUM_PREINTERNED_RE_LATE_BOUNDS_V)
+                    .map(|v| {
+                        mk(ty::ReLateBound(
+                            ty::DebruijnIndex::from(i),
+                            ty::BoundRegion {
+                                var: ty::BoundVar::from(v),
+                                kind: ty::BrAnon(v, None),
+                            },
+                        ))
+                    })
+                    .collect()
+            })
+            .collect();
+
+        CommonLifetimes {
+            re_static: mk(ty::ReStatic),
+            re_erased: mk(ty::ReErased),
+            re_vars,
+            re_late_bounds,
+        }
     }
 }
 
@@ -697,15 +738,15 @@ impl<'tcx> TyCtxt<'tcx> {
 
     /// Constructs a `RegionKind::ReError` lifetime.
     #[track_caller]
-    pub fn re_error(self, reported: ErrorGuaranteed) -> Region<'tcx> {
-        self.mk_region(ty::ReError(reported))
+    pub fn mk_re_error(self, reported: ErrorGuaranteed) -> Region<'tcx> {
+        self.intern_region(ty::ReError(reported))
     }
 
     /// Constructs a `RegionKind::ReError` lifetime and registers a `delay_span_bug` to ensure it
     /// gets used.
     #[track_caller]
-    pub fn re_error_misc(self) -> Region<'tcx> {
-        self.re_error_with_message(
+    pub fn mk_re_error_misc(self) -> Region<'tcx> {
+        self.mk_re_error_with_message(
             DUMMY_SP,
             "RegionKind::ReError constructed but no error reported",
         )
@@ -714,9 +755,9 @@ impl<'tcx> TyCtxt<'tcx> {
     /// Constructs a `RegionKind::ReError` lifetime and registers a `delay_span_bug` with the given
     /// `msg` to ensure it gets used.
     #[track_caller]
-    pub fn re_error_with_message<S: Into<MultiSpan>>(self, span: S, msg: &str) -> Region<'tcx> {
+    pub fn mk_re_error_with_message<S: Into<MultiSpan>>(self, span: S, msg: &str) -> Region<'tcx> {
         let reported = self.sess.delay_span_bug(span, msg);
-        self.re_error(reported)
+        self.mk_re_error(reported)
     }
 
     /// Like [TyCtxt::ty_error] but for constants, with current `ErrorGuaranteed`
@@ -1517,7 +1558,7 @@ macro_rules! direct_interners {
 }
 
 direct_interners! {
-    region: mk_region(RegionKind<'tcx>): Region -> Region<'tcx>,
+    region: intern_region(RegionKind<'tcx>): Region -> Region<'tcx>,
     const_: mk_const_internal(ConstData<'tcx>): Const -> Const<'tcx>,
     const_allocation: intern_const_alloc(Allocation): ConstAllocation -> ConstAllocation<'tcx>,
     layout: intern_layout(LayoutS): Layout -> Layout<'tcx>,
@@ -1631,13 +1672,6 @@ impl<'tcx> TyCtxt<'tcx> {
         })
     }
 
-    /// Same a `self.mk_region(kind)`, but avoids accessing the interners if
-    /// `*r == kind`.
-    #[inline]
-    pub fn reuse_or_mk_region(self, r: Region<'tcx>, kind: RegionKind<'tcx>) -> Region<'tcx> {
-        if *r == kind { r } else { self.mk_region(kind) }
-    }
-
     // Avoid this in favour of more specific `mk_*` methods, where possible.
     #[allow(rustc::usage_of_ty_tykind)]
     #[inline]
@@ -1966,7 +2000,7 @@ impl<'tcx> TyCtxt<'tcx> {
     pub fn mk_param_from_def(self, param: &ty::GenericParamDef) -> GenericArg<'tcx> {
         match param.kind {
             GenericParamDefKind::Lifetime => {
-                self.mk_region(ty::ReEarlyBound(param.to_early_bound_region_data())).into()
+                self.mk_re_early_bound(param.to_early_bound_region_data()).into()
             }
             GenericParamDefKind::Type { .. } => self.mk_ty_param(param.index, param.name).into(),
             GenericParamDefKind::Const { .. } => self
@@ -1998,6 +2032,66 @@ impl<'tcx> TyCtxt<'tcx> {
         self.mk_alias(ty::Opaque, self.mk_alias_ty(def_id, substs))
     }
 
+    #[inline]
+    pub fn mk_re_early_bound(self, early_bound_region: ty::EarlyBoundRegion) -> Region<'tcx> {
+        self.intern_region(ty::ReEarlyBound(early_bound_region))
+    }
+
+    #[inline]
+    pub fn mk_re_late_bound(
+        self,
+        debruijn: ty::DebruijnIndex,
+        bound_region: ty::BoundRegion,
+    ) -> Region<'tcx> {
+        // Use a pre-interned one when possible.
+        if let ty::BoundRegion { var, kind: ty::BrAnon(v, None) } = bound_region
+            && var.as_u32() == v
+            && let Some(inner) = self.lifetimes.re_late_bounds.get(debruijn.as_usize())
+            && let Some(re) = inner.get(v as usize).copied()
+        {
+            re
+        } else {
+            self.intern_region(ty::ReLateBound(debruijn, bound_region))
+        }
+    }
+
+    #[inline]
+    pub fn mk_re_free(self, scope: DefId, bound_region: ty::BoundRegionKind) -> Region<'tcx> {
+        self.intern_region(ty::ReFree(ty::FreeRegion { scope, bound_region }))
+    }
+
+    #[inline]
+    pub fn mk_re_var(self, v: ty::RegionVid) -> Region<'tcx> {
+        // Use a pre-interned one when possible.
+        self.lifetimes
+            .re_vars
+            .get(v.as_usize())
+            .copied()
+            .unwrap_or_else(|| self.intern_region(ty::ReVar(v)))
+    }
+
+    #[inline]
+    pub fn mk_re_placeholder(self, placeholder: ty::PlaceholderRegion) -> Region<'tcx> {
+        self.intern_region(ty::RePlaceholder(placeholder))
+    }
+
+    // Avoid this in favour of more specific `mk_re_*` methods, where possible,
+    // to avoid the cost of the `match`.
+    pub fn mk_region(self, kind: ty::RegionKind<'tcx>) -> Region<'tcx> {
+        match kind {
+            ty::ReEarlyBound(region) => self.mk_re_early_bound(region),
+            ty::ReLateBound(debruijn, region) => self.mk_re_late_bound(debruijn, region),
+            ty::ReFree(ty::FreeRegion { scope, bound_region }) => {
+                self.mk_re_free(scope, bound_region)
+            }
+            ty::ReStatic => self.lifetimes.re_static,
+            ty::ReVar(vid) => self.mk_re_var(vid),
+            ty::RePlaceholder(region) => self.mk_re_placeholder(region),
+            ty::ReErased => self.lifetimes.re_erased,
+            ty::ReError(reported) => self.mk_re_error(reported),
+        }
+    }
+
     pub fn mk_place_field(self, place: Place<'tcx>, f: Field, ty: Ty<'tcx>) -> Place<'tcx> {
         self.mk_place_elem(place, PlaceElem::Field(f, ty))
     }
diff --git a/compiler/rustc_middle/src/ty/fold.rs b/compiler/rustc_middle/src/ty/fold.rs
index 352daa8fc29..ee36e60bff1 100644
--- a/compiler/rustc_middle/src/ty/fold.rs
+++ b/compiler/rustc_middle/src/ty/fold.rs
@@ -234,7 +234,7 @@ where
                     // debruijn index. Then we adjust it to the
                     // correct depth.
                     assert_eq!(debruijn1, ty::INNERMOST);
-                    self.tcx.reuse_or_mk_region(region, ty::ReLateBound(debruijn, br))
+                    self.tcx.mk_re_late_bound(debruijn, br)
                 } else {
                     region
                 }
@@ -349,10 +349,7 @@ impl<'tcx> TyCtxt<'tcx> {
         T: TypeFoldable<'tcx>,
     {
         self.replace_late_bound_regions_uncached(value, |br| {
-            self.mk_region(ty::ReFree(ty::FreeRegion {
-                scope: all_outlive_scope,
-                bound_region: br.kind,
-            }))
+            self.mk_re_free(all_outlive_scope, br.kind)
         })
     }
 
@@ -365,10 +362,10 @@ impl<'tcx> TyCtxt<'tcx> {
             value,
             FnMutDelegate {
                 regions: &mut |r: ty::BoundRegion| {
-                    self.mk_region(ty::ReLateBound(
+                    self.mk_re_late_bound(
                         ty::INNERMOST,
                         ty::BoundRegion { var: shift_bv(r.var), kind: r.kind },
-                    ))
+                    )
                 },
                 types: &mut |t: ty::BoundTy| {
                     self.mk_bound(ty::INNERMOST, ty::BoundTy { var: shift_bv(t.var), kind: t.kind })
@@ -409,7 +406,7 @@ impl<'tcx> TyCtxt<'tcx> {
                     })
                     .expect_region();
                 let br = ty::BoundRegion { var, kind };
-                self.tcx.mk_region(ty::ReLateBound(ty::INNERMOST, br))
+                self.tcx.mk_re_late_bound(ty::INNERMOST, br)
             }
             fn replace_ty(&mut self, bt: ty::BoundTy) -> Ty<'tcx> {
                 let entry = self.map.entry(bt.var);
@@ -479,8 +476,7 @@ impl<'tcx> ir::TypeFolder<TyCtxt<'tcx>> for Shifter<'tcx> {
         match *r {
             ty::ReLateBound(debruijn, br) if debruijn >= self.current_index => {
                 let debruijn = debruijn.shifted_in(self.amount);
-                let shifted = ty::ReLateBound(debruijn, br);
-                self.tcx.mk_region(shifted)
+                self.tcx.mk_re_late_bound(debruijn, br)
             }
             _ => r,
         }
@@ -521,7 +517,7 @@ pub fn shift_region<'tcx>(
 ) -> ty::Region<'tcx> {
     match *region {
         ty::ReLateBound(debruijn, br) if amount > 0 => {
-            tcx.mk_region(ty::ReLateBound(debruijn.shifted_in(amount), br))
+            tcx.mk_re_late_bound(debruijn.shifted_in(amount), br)
         }
         _ => region,
     }
diff --git a/compiler/rustc_middle/src/ty/generics.rs b/compiler/rustc_middle/src/ty/generics.rs
index ea95a38f272..c29a94c9714 100644
--- a/compiler/rustc_middle/src/ty/generics.rs
+++ b/compiler/rustc_middle/src/ty/generics.rs
@@ -100,7 +100,7 @@ impl GenericParamDef {
         preceding_substs: &[ty::GenericArg<'tcx>],
     ) -> ty::GenericArg<'tcx> {
         match &self.kind {
-            ty::GenericParamDefKind::Lifetime => tcx.re_error_misc().into(),
+            ty::GenericParamDefKind::Lifetime => tcx.mk_re_error_misc().into(),
             ty::GenericParamDefKind::Type { .. } => tcx.ty_error().into(),
             ty::GenericParamDefKind::Const { .. } => {
                 tcx.const_error(tcx.bound_type_of(self.def_id).subst(tcx, preceding_substs)).into()
diff --git a/compiler/rustc_middle/src/ty/opaque_types.rs b/compiler/rustc_middle/src/ty/opaque_types.rs
index 66c878c8b63..8aeef4684b3 100644
--- a/compiler/rustc_middle/src/ty/opaque_types.rs
+++ b/compiler/rustc_middle/src/ty/opaque_types.rs
@@ -143,7 +143,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for ReverseMapper<'tcx> {
                     )
                     .emit();
 
-                self.interner().re_error(e)
+                self.interner().mk_re_error(e)
             }
         }
     }
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index f50a5d89d3d..1a228e99eff 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -182,7 +182,7 @@ impl<'tcx> RegionHighlightMode<'tcx> {
 
     /// Convenience wrapper for `highlighting_region`.
     pub fn highlighting_region_vid(&mut self, vid: ty::RegionVid, number: usize) {
-        self.highlighting_region(self.tcx.mk_region(ty::ReVar(vid)), number)
+        self.highlighting_region(self.tcx.mk_re_var(vid), number)
     }
 
     /// Returns `Some(n)` with the number to use for the given region, if any.
@@ -2271,7 +2271,7 @@ impl<'a, 'tcx> ty::ir::TypeFolder<TyCtxt<'tcx>> for RegionFolder<'a, 'tcx> {
         };
         if let ty::ReLateBound(debruijn1, br) = *region {
             assert_eq!(debruijn1, ty::INNERMOST);
-            self.tcx.mk_region(ty::ReLateBound(self.current_index, br))
+            self.tcx.mk_re_late_bound(self.current_index, br)
         } else {
             region
         }
@@ -2383,10 +2383,10 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
                         if let Some(lt_idx) = lifetime_idx {
                             if lt_idx > binder_level_idx {
                                 let kind = ty::BrNamed(CRATE_DEF_ID.to_def_id(), name);
-                                return tcx.mk_region(ty::ReLateBound(
+                                return tcx.mk_re_late_bound(
                                     ty::INNERMOST,
                                     ty::BoundRegion { var: br.var, kind },
-                                ));
+                                );
                             }
                         }
 
@@ -2398,10 +2398,10 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
                         if let Some(lt_idx) = lifetime_idx {
                             if lt_idx > binder_level_idx {
                                 let kind = ty::BrNamed(def_id, name);
-                                return tcx.mk_region(ty::ReLateBound(
+                                return tcx.mk_re_late_bound(
                                     ty::INNERMOST,
                                     ty::BoundRegion { var: br.var, kind },
-                                ));
+                                );
                             }
                         }
 
@@ -2411,10 +2411,10 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
                         if let Some(lt_idx) = lifetime_idx {
                             if lt_idx > binder_level_idx {
                                 let kind = br.kind;
-                                return tcx.mk_region(ty::ReLateBound(
+                                return tcx.mk_re_late_bound(
                                     ty::INNERMOST,
                                     ty::BoundRegion { var: br.var, kind },
-                                ));
+                                );
                             }
                         }
 
@@ -2426,7 +2426,7 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
                     start_or_continue(&mut self, "for<", ", ");
                     do_continue(&mut self, name);
                 }
-                tcx.mk_region(ty::ReLateBound(ty::INNERMOST, ty::BoundRegion { var: br.var, kind }))
+                tcx.mk_re_late_bound(ty::INNERMOST, ty::BoundRegion { var: br.var, kind })
             };
             let mut folder = RegionFolder {
                 tcx,
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index c613b3627f2..85c63131bff 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -1187,7 +1187,7 @@ impl<'tcx> FallibleTypeFolder<TyCtxt<'tcx>> for SkipBindersAt<'tcx> {
             if index == self.index {
                 Err(())
             } else {
-                Ok(self.interner().mk_region(ty::ReLateBound(index.shifted_out(1), bv)))
+                Ok(self.interner().mk_re_late_bound(index.shifted_out(1), bv))
             }
         } else {
             r.try_super_fold_with(self)
diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs
index 35831ff8706..7f5ffe6f27a 100644
--- a/compiler/rustc_middle/src/ty/util.rs
+++ b/compiler/rustc_middle/src/ty/util.rs
@@ -564,14 +564,14 @@ impl<'tcx> TyCtxt<'tcx> {
         self,
         closure_def_id: DefId,
         closure_substs: SubstsRef<'tcx>,
-        env_region: ty::RegionKind<'tcx>,
+        env_region: ty::Region<'tcx>,
     ) -> Option<Ty<'tcx>> {
         let closure_ty = self.mk_closure(closure_def_id, closure_substs);
         let closure_kind_ty = closure_substs.as_closure().kind_ty();
         let closure_kind = closure_kind_ty.to_opt_closure_kind()?;
         let env_ty = match closure_kind {
-            ty::ClosureKind::Fn => self.mk_imm_ref(self.mk_region(env_region), closure_ty),
-            ty::ClosureKind::FnMut => self.mk_mut_ref(self.mk_region(env_region), closure_ty),
+            ty::ClosureKind::Fn => self.mk_imm_ref(env_region, closure_ty),
+            ty::ClosureKind::FnMut => self.mk_mut_ref(env_region, closure_ty),
             ty::ClosureKind::FnOnce => closure_ty,
         };
         Some(env_ty)
diff --git a/compiler/rustc_mir_build/src/thir/cx/mod.rs b/compiler/rustc_mir_build/src/thir/cx/mod.rs
index 10df4b22952..c9fa599f52d 100644
--- a/compiler/rustc_mir_build/src/thir/cx/mod.rs
+++ b/compiler/rustc_mir_build/src/thir/cx/mod.rs
@@ -140,7 +140,7 @@ impl<'tcx> Cx<'tcx> {
                     var: ty::BoundVar::from_usize(bound_vars.len() - 1),
                     kind: ty::BrEnv,
                 };
-                let env_region = ty::ReLateBound(ty::INNERMOST, br);
+                let env_region = self.tcx.mk_re_late_bound(ty::INNERMOST, br);
                 let closure_env_ty =
                     self.tcx.closure_env_ty(closure_def_id, closure_substs, env_region).unwrap();
                 let liberated_closure_env_ty = self.tcx.erase_late_bound_regions(
diff --git a/compiler/rustc_mir_transform/src/large_enums.rs b/compiler/rustc_mir_transform/src/large_enums.rs
index 194c41c6ba1..2ca33a624e2 100644
--- a/compiler/rustc_mir_transform/src/large_enums.rs
+++ b/compiler/rustc_mir_transform/src/large_enums.rs
@@ -3,7 +3,7 @@ use crate::MirPass;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_middle::mir::interpret::AllocId;
 use rustc_middle::mir::*;
-use rustc_middle::ty::{self, AdtDef, Const, ParamEnv, Ty, TyCtxt};
+use rustc_middle::ty::{self, AdtDef, ParamEnv, Ty, TyCtxt};
 use rustc_session::Session;
 use rustc_target::abi::{HasDataLayout, Size, TagEncoding, Variants};
 
@@ -141,10 +141,7 @@ impl EnumSizeOpt {
                         self.candidate(tcx, param_env, ty, &mut alloc_cache)?;
                     let alloc = tcx.global_alloc(alloc_id).unwrap_memory();
 
-                    let tmp_ty = tcx.mk_ty(ty::Array(
-                        tcx.types.usize,
-                        Const::from_target_usize(tcx, num_variants as u64),
-                    ));
+                    let tmp_ty = tcx.mk_array(tcx.types.usize, num_variants as u64);
 
                     let size_array_local = local_decls.push(LocalDecl::new(tmp_ty, span));
                     let store_live = Statement {
diff --git a/compiler/rustc_trait_selection/src/traits/object_safety.rs b/compiler/rustc_trait_selection/src/traits/object_safety.rs
index 7ef39b20107..84c50a3aa8a 100644
--- a/compiler/rustc_trait_selection/src/traits/object_safety.rs
+++ b/compiler/rustc_trait_selection/src/traits/object_safety.rs
@@ -527,8 +527,7 @@ fn virtual_call_violation_for_method<'tcx>(
                 }
             }
 
-            let trait_object_ty =
-                object_ty_for_trait(tcx, trait_def_id, tcx.mk_region(ty::ReStatic));
+            let trait_object_ty = object_ty_for_trait(tcx, trait_def_id, tcx.lifetimes.re_static);
 
             // e.g., `Rc<dyn Trait>`
             let trait_object_receiver =
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs
index a380d4697ea..7ddffe595be 100644
--- a/compiler/rustc_trait_selection/src/traits/project.rs
+++ b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -767,7 +767,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for BoundVarReplacer<'_, 'tcx> {
                 let universe = self.universe_for(debruijn);
                 let p = ty::PlaceholderRegion { universe, name: br.kind };
                 self.mapped_regions.insert(p, br);
-                self.infcx.tcx.mk_region(ty::RePlaceholder(p))
+                self.infcx.tcx.mk_re_placeholder(p)
             }
             _ => r,
         }
@@ -888,7 +888,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for PlaceholderReplacer<'_, 'tcx> {
                         let db = ty::DebruijnIndex::from_usize(
                             self.universe_indices.len() - index + self.current_index.as_usize() - 1,
                         );
-                        self.interner().mk_region(ty::ReLateBound(db, *replace_var))
+                        self.interner().mk_re_late_bound(db, *replace_var)
                     }
                     None => r1,
                 }
diff --git a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
index dc5bcb48cad..9770813e86d 100644
--- a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
@@ -540,13 +540,13 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                                 let kind = ty::BoundRegionKind::BrNamed(param.def_id, param.name);
                                 let bound_var = ty::BoundVariableKind::Region(kind);
                                 bound_vars.push(bound_var);
-                                tcx.mk_region(ty::ReLateBound(
+                                tcx.mk_re_late_bound(
                                     ty::INNERMOST,
                                     ty::BoundRegion {
                                         var: ty::BoundVar::from_usize(bound_vars.len() - 1),
                                         kind,
                                     },
-                                ))
+                                )
                                 .into()
                             }
                             GenericParamDefKind::Const { .. } => {
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index fc9678233c3..215d39ef374 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -3023,7 +3023,7 @@ fn bind_generator_hidden_types_above<'tcx>(
                             kind: ty::BrAnon(counter, None),
                         };
                         counter += 1;
-                        r = tcx.mk_region(ty::ReLateBound(current_depth, br));
+                        r = tcx.mk_re_late_bound(current_depth, br);
                     }
                     r
                 })
diff --git a/compiler/rustc_traits/src/chalk/db.rs b/compiler/rustc_traits/src/chalk/db.rs
index 20725c656de..bb2b3ac6609 100644
--- a/compiler/rustc_traits/src/chalk/db.rs
+++ b/compiler/rustc_traits/src/chalk/db.rs
@@ -732,7 +732,7 @@ fn bound_vars_for_item(tcx: TyCtxt<'_>, def_id: DefId) -> SubstsRef<'_> {
                 var: ty::BoundVar::from_usize(substs.len()),
                 kind: ty::BrAnon(substs.len() as u32, None),
             };
-            tcx.mk_region(ty::ReLateBound(ty::INNERMOST, br)).into()
+            tcx.mk_re_late_bound(ty::INNERMOST, br).into()
         }
 
         ty::GenericParamDefKind::Const { .. } => tcx
diff --git a/compiler/rustc_traits/src/chalk/lowering.rs b/compiler/rustc_traits/src/chalk/lowering.rs
index 2978fc4ed8c..9abbd0c5b34 100644
--- a/compiler/rustc_traits/src/chalk/lowering.rs
+++ b/compiler/rustc_traits/src/chalk/lowering.rs
@@ -521,8 +521,9 @@ impl<'tcx> LowerInto<'tcx, chalk_ir::Lifetime<RustInterner<'tcx>>> for Region<'t
 
 impl<'tcx> LowerInto<'tcx, Region<'tcx>> for &chalk_ir::Lifetime<RustInterner<'tcx>> {
     fn lower_into(self, interner: RustInterner<'tcx>) -> Region<'tcx> {
-        let kind = match self.data(interner) {
-            chalk_ir::LifetimeData::BoundVar(var) => ty::ReLateBound(
+        let tcx = interner.tcx;
+        match self.data(interner) {
+            chalk_ir::LifetimeData::BoundVar(var) => tcx.mk_re_late_bound(
                 ty::DebruijnIndex::from_u32(var.debruijn.depth()),
                 ty::BoundRegion {
                     var: ty::BoundVar::from_usize(var.index),
@@ -530,15 +531,14 @@ impl<'tcx> LowerInto<'tcx, Region<'tcx>> for &chalk_ir::Lifetime<RustInterner<'t
                 },
             ),
             chalk_ir::LifetimeData::InferenceVar(_var) => unimplemented!(),
-            chalk_ir::LifetimeData::Placeholder(p) => ty::RePlaceholder(ty::Placeholder {
+            chalk_ir::LifetimeData::Placeholder(p) => tcx.mk_re_placeholder(ty::Placeholder {
                 universe: ty::UniverseIndex::from_usize(p.ui.counter),
                 name: ty::BoundRegionKind::BrAnon(p.idx as u32, None),
             }),
-            chalk_ir::LifetimeData::Static => return interner.tcx.lifetimes.re_static,
-            chalk_ir::LifetimeData::Erased => return interner.tcx.lifetimes.re_erased,
+            chalk_ir::LifetimeData::Static => tcx.lifetimes.re_static,
+            chalk_ir::LifetimeData::Erased => tcx.lifetimes.re_erased,
             chalk_ir::LifetimeData::Phantom(void, _) => match *void {},
-        };
-        interner.tcx.mk_region(kind)
+        }
     }
 }
 
@@ -1025,7 +1025,7 @@ impl<'a, 'tcx> TypeFolder<TyCtxt<'tcx>> for NamedBoundVarSubstitutor<'a, 'tcx> {
                 ty::BrNamed(def_id, _name) => match self.named_parameters.get(&def_id) {
                     Some(idx) => {
                         let new_br = ty::BoundRegion { var: br.var, kind: ty::BrAnon(*idx, None) };
-                        return self.tcx.mk_region(ty::ReLateBound(index, new_br));
+                        return self.tcx.mk_re_late_bound(index, new_br);
                     }
                     None => panic!("Missing `BrNamed`."),
                 },
@@ -1107,7 +1107,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for ParamsSubstitutor<'tcx> {
                         var: ty::BoundVar::from_u32(*idx),
                         kind: ty::BrAnon(*idx, None),
                     };
-                    self.tcx.mk_region(ty::ReLateBound(self.binder_index, br))
+                    self.tcx.mk_re_late_bound(self.binder_index, br)
                 }
                 None => {
                     let idx = self.named_regions.len() as u32;
@@ -1116,7 +1116,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for ParamsSubstitutor<'tcx> {
                         kind: ty::BrAnon(idx, None),
                     };
                     self.named_regions.insert(_re.def_id, idx);
-                    self.tcx.mk_region(ty::ReLateBound(self.binder_index, br))
+                    self.tcx.mk_re_late_bound(self.binder_index, br)
                 }
             },
 
diff --git a/compiler/rustc_ty_utils/src/abi.rs b/compiler/rustc_ty_utils/src/abi.rs
index ad5527f5a77..03025e186b3 100644
--- a/compiler/rustc_ty_utils/src/abi.rs
+++ b/compiler/rustc_ty_utils/src/abi.rs
@@ -70,7 +70,7 @@ fn fn_sig_for_fn_abi<'tcx>(
                 var: ty::BoundVar::from_usize(bound_vars.len() - 1),
                 kind: ty::BoundRegionKind::BrEnv,
             };
-            let env_region = ty::ReLateBound(ty::INNERMOST, br);
+            let env_region = tcx.mk_re_late_bound(ty::INNERMOST, br);
             let env_ty = tcx.closure_env_ty(def_id, substs, env_region).unwrap();
 
             let sig = sig.skip_binder();
@@ -95,8 +95,7 @@ fn fn_sig_for_fn_abi<'tcx>(
                 var: ty::BoundVar::from_usize(bound_vars.len() - 1),
                 kind: ty::BoundRegionKind::BrEnv,
             };
-            let env_region = ty::ReLateBound(ty::INNERMOST, br);
-            let env_ty = tcx.mk_mut_ref(tcx.mk_region(env_region), ty);
+            let env_ty = tcx.mk_mut_ref(tcx.mk_re_late_bound(ty::INNERMOST, br), ty);
 
             let pin_did = tcx.require_lang_item(LangItem::Pin, None);
             let pin_adt_ref = tcx.adt_def(pin_did);