On-demandify region mapping

13 files changed, 84 insertions, 44 deletions

diff --git a/src/librustc/cfg/construct.rs b/src/librustc/cfg/construct.rs
index d234e408a22..8471d2ae4e3 100644
--- a/src/librustc/cfg/construct.rs
+++ b/src/librustc/cfg/construct.rs
@@ -583,11 +583,11 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
                         scope_id: ast::NodeId,
                         to_index: CFGIndex) {
         let mut data = CFGEdgeData { exiting_scopes: vec![] };
-        let mut scope = self.tcx.region_maps.node_extent(from_expr.id);
-        let target_scope = self.tcx.region_maps.node_extent(scope_id);
+        let mut scope = self.tcx.region_maps().node_extent(from_expr.id);
+        let target_scope = self.tcx.region_maps().node_extent(scope_id);
         while scope != target_scope {
-            data.exiting_scopes.push(scope.node_id(&self.tcx.region_maps));
-            scope = self.tcx.region_maps.encl_scope(scope);
+            data.exiting_scopes.push(scope.node_id(&self.tcx.region_maps()));
+            scope = self.tcx.region_maps().encl_scope(scope);
         }
         self.graph.add_edge(from_index, to_index, data);
     }
diff --git a/src/librustc/ich/impls_ty.rs b/src/librustc/ich/impls_ty.rs
index 16af98c2035..d68a62e5030 100644
--- a/src/librustc/ich/impls_ty.rs
+++ b/src/librustc/ich/impls_ty.rs
@@ -438,7 +438,7 @@ impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for ::middle::region::
                                           hcx: &mut StableHashingContext<'a, 'tcx>,
                                           hasher: &mut StableHasher<W>) {
         hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| {
-            hcx.tcx().region_maps.code_extent_data(*self).hash_stable(hcx, hasher);
+            hcx.tcx().region_maps().code_extent_data(*self).hash_stable(hcx, hasher);
         });
     }
 }
diff --git a/src/librustc/infer/error_reporting/mod.rs b/src/librustc/infer/error_reporting/mod.rs
index dcbe50de2e9..febf6af8763 100644
--- a/src/librustc/infer/error_reporting/mod.rs
+++ b/src/librustc/infer/error_reporting/mod.rs
@@ -123,14 +123,14 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                     format!("{}unknown scope: {:?}{}.  Please report a bug.",
                             prefix, scope, suffix)
                 };
-                let span = match scope.span(&self.region_maps, &self.hir) {
+                let span = match scope.span(&self.region_maps(), &self.hir) {
                     Some(s) => s,
                     None => {
                         err.note(&unknown_scope());
                         return;
                     }
                 };
-                let tag = match self.hir.find(scope.node_id(&self.region_maps)) {
+                let tag = match self.hir.find(scope.node_id(&self.region_maps())) {
                     Some(hir_map::NodeBlock(_)) => "block",
                     Some(hir_map::NodeExpr(expr)) => match expr.node {
                         hir::ExprCall(..) => "call",
@@ -150,7 +150,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                         return;
                     }
                 };
-                let scope_decorated_tag = match self.region_maps.code_extent_data(scope) {
+                let scope_decorated_tag = match self.region_maps().code_extent_data(scope) {
                     region::CodeExtentData::Misc(_) => tag,
                     region::CodeExtentData::CallSiteScope { .. } => {
                         "scope of call-site for function"
@@ -183,7 +183,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                     }
                 };
 
-                let node = fr.scope.node_id(&self.region_maps);
+                let node = fr.scope.node_id(&self.region_maps());
                 let unknown;
                 let tag = match self.hir.find(node) {
                     Some(hir_map::NodeBlock(_)) |
diff --git a/src/librustc/infer/region_inference/graphviz.rs b/src/librustc/infer/region_inference/graphviz.rs
index a67049f7285..f8d188fcaed 100644
--- a/src/librustc/infer/region_inference/graphviz.rs
+++ b/src/librustc/infer/region_inference/graphviz.rs
@@ -159,7 +159,7 @@ impl<'a, 'gcx, 'tcx> ConstraintGraph<'a, 'gcx, 'tcx> {
                 add_node(n2);
             }
 
-            tcx.region_maps.each_encl_scope(|sub, sup| {
+            tcx.region_maps().each_encl_scope(|sub, sup| {
                 add_node(Node::Region(ty::ReScope(*sub)));
                 add_node(Node::Region(ty::ReScope(*sup)));
             });
@@ -245,7 +245,7 @@ impl<'a, 'gcx, 'tcx> dot::GraphWalk<'a> for ConstraintGraph<'a, 'gcx, 'tcx> {
     fn edges(&self) -> dot::Edges<Edge<'tcx>> {
         debug!("constraint graph has {} edges", self.map.len());
         let mut v: Vec<_> = self.map.keys().map(|e| Edge::Constraint(*e)).collect();
-        self.tcx.region_maps.each_encl_scope(|sub, sup| v.push(Edge::EnclScope(*sub, *sup)));
+        self.tcx.region_maps().each_encl_scope(|sub, sup| v.push(Edge::EnclScope(*sub, *sup)));
         debug!("region graph has {} edges", v.len());
         Cow::Owned(v)
     }
diff --git a/src/librustc/infer/region_inference/mod.rs b/src/librustc/infer/region_inference/mod.rs
index fa6775737b5..19752f3363a 100644
--- a/src/librustc/infer/region_inference/mod.rs
+++ b/src/librustc/infer/region_inference/mod.rs
@@ -938,7 +938,7 @@ impl<'a, 'gcx, 'tcx> RegionVarBindings<'a, 'gcx, 'tcx> {
                 // A "free" region can be interpreted as "some region
                 // at least as big as the block fr.scope_id".  So, we can
                 // reasonably compare free regions and scopes:
-                let r_id = self.tcx.region_maps.nearest_common_ancestor(fr.scope, s_id);
+                let r_id = self.tcx.region_maps().nearest_common_ancestor(fr.scope, s_id);
 
                 if r_id == fr.scope {
                     // if the free region's scope `fr.scope_id` is bigger than
@@ -957,7 +957,7 @@ impl<'a, 'gcx, 'tcx> RegionVarBindings<'a, 'gcx, 'tcx> {
                 // subtype of the region corresponding to an inner
                 // block.
                 self.tcx.mk_region(ReScope(
-                    self.tcx.region_maps.nearest_common_ancestor(a_id, b_id)))
+                    self.tcx.region_maps().nearest_common_ancestor(a_id, b_id)))
             }
 
             (&ReFree(a_fr), &ReFree(b_fr)) => {
diff --git a/src/librustc/middle/free_region.rs b/src/librustc/middle/free_region.rs
index 2bfa8dec0bf..f622dfc683b 100644
--- a/src/librustc/middle/free_region.rs
+++ b/src/librustc/middle/free_region.rs
@@ -136,10 +136,10 @@ impl FreeRegionMap {
                     true,
 
                 (&ty::ReScope(sub_scope), &ty::ReScope(super_scope)) =>
-                    tcx.region_maps.is_subscope_of(sub_scope, super_scope),
+                    tcx.region_maps().is_subscope_of(sub_scope, super_scope),
 
                 (&ty::ReScope(sub_scope), &ty::ReFree(fr)) =>
-                    tcx.region_maps.is_subscope_of(sub_scope, fr.scope) ||
+                    tcx.region_maps().is_subscope_of(sub_scope, fr.scope) ||
                     self.is_static(fr),
 
                 (&ty::ReFree(sub_fr), &ty::ReFree(super_fr)) =>
diff --git a/src/librustc/middle/liveness.rs b/src/librustc/middle/liveness.rs
index 63104678862..73c8d1db312 100644
--- a/src/librustc/middle/liveness.rs
+++ b/src/librustc/middle/liveness.rs
@@ -1441,7 +1441,7 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
         // and must outlive the *call-site* of the function.
         let fn_ret =
             self.ir.tcx.liberate_late_bound_regions(
-                self.ir.tcx.region_maps.call_site_extent(id, body.value.id),
+                self.ir.tcx.region_maps().call_site_extent(id, body.value.id),
                 &fn_ret);
 
         if !fn_ret.is_never() && self.live_on_entry(entry_ln, self.s.no_ret_var).is_some() {
diff --git a/src/librustc/middle/mem_categorization.rs b/src/librustc/middle/mem_categorization.rs
index 9db6dffb0e8..b398255aede 100644
--- a/src/librustc/middle/mem_categorization.rs
+++ b/src/librustc/middle/mem_categorization.rs
@@ -796,7 +796,7 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
             // The environment of a closure is guaranteed to
             // outlive any bindings introduced in the body of the
             // closure itself.
-            scope: self.tcx().region_maps.item_extent(fn_body_id),
+            scope: self.tcx().region_maps().item_extent(fn_body_id),
             bound_region: ty::BrEnv
         }));
 
@@ -845,7 +845,7 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
     pub fn temporary_scope(&self, id: ast::NodeId) -> (&'tcx ty::Region, &'tcx ty::Region)
     {
         let (scope, old_scope) =
-            self.tcx().region_maps.old_and_new_temporary_scope(id);
+            self.tcx().region_maps().old_and_new_temporary_scope(id);
         (self.tcx().mk_region(match scope {
             Some(scope) => ty::ReScope(scope),
             None => ty::ReStatic
diff --git a/src/librustc/middle/region.rs b/src/librustc/middle/region.rs
index 0676075930d..18e76ff5011 100644
--- a/src/librustc/middle/region.rs
+++ b/src/librustc/middle/region.rs
@@ -16,7 +16,6 @@
 //! Most of the documentation on regions can be found in
 //! `middle/infer/region_inference/README.md`
 
-use dep_graph::DepNode;
 use hir::map as hir_map;
 use session::Session;
 use util::nodemap::{FxHashMap, NodeMap, NodeSet};
@@ -26,11 +25,15 @@ use std::cell::RefCell;
 use std::collections::hash_map::Entry;
 use std::fmt;
 use std::mem;
+use std::rc::Rc;
 use syntax::codemap;
 use syntax::ast::{self, NodeId};
 use syntax_pos::Span;
+use ty::TyCtxt;
+use ty::maps::Providers;
 
 use hir;
+use hir::def_id::{CrateNum, LOCAL_CRATE};
 use hir::intravisit::{self, Visitor, FnKind, NestedVisitorMap};
 use hir::{Block, Item, FnDecl, Arm, Pat, PatKind, Stmt, Expr, Local};
 
@@ -44,8 +47,13 @@ impl fmt::Debug for CodeExtent {
 
         ty::tls::with_opt(|opt_tcx| {
             if let Some(tcx) = opt_tcx {
-                if let Some(data) = tcx.region_maps.code_extents.borrow().get(self.0 as usize) {
-                    write!(f, "/{:?}", data)?;
+                let region_maps = tcx.region_maps();
+                {
+                    let code_extents = &region_maps.code_extents;
+                    if let Some(data) = code_extents.borrow().get(self.0 as usize) {
+                        write!(f, "/{:?}", data)?;
+                    }
+                    mem::drop(code_extents); // FIXME why is this necessary?
                 }
             }
             Ok(())
@@ -1256,9 +1264,19 @@ impl<'hir, 'a> Visitor<'hir> for RegionResolutionVisitor<'hir, 'a> {
     }
 }
 
-pub fn resolve_crate(sess: &Session, map: &hir_map::Map) -> RegionMaps {
-    let _task = map.dep_graph.in_task(DepNode::RegionResolveCrate);
-    let krate = map.krate();
+pub fn resolve_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Rc<RegionMaps> {
+    tcx.region_resolve_crate(LOCAL_CRATE)
+}
+
+fn region_resolve_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, crate_num: CrateNum)
+    -> Rc<RegionMaps>
+{
+    debug_assert!(crate_num == LOCAL_CRATE);
+
+    let sess = &tcx.sess;
+    let hir_map = &tcx.hir;
+
+    let krate = hir_map.krate();
 
     let maps = RegionMaps {
         code_extents: RefCell::new(vec![]),
@@ -1279,7 +1297,7 @@ pub fn resolve_crate(sess: &Session, map: &hir_map::Map) -> RegionMaps {
         let mut visitor = RegionResolutionVisitor {
             sess: sess,
             region_maps: &maps,
-            map: map,
+            map: hir_map,
             cx: Context {
                 root_id: None,
                 parent: ROOT_CODE_EXTENT,
@@ -1289,5 +1307,12 @@ pub fn resolve_crate(sess: &Session, map: &hir_map::Map) -> RegionMaps {
         };
         krate.visit_all_item_likes(&mut visitor.as_deep_visitor());
     }
-    return maps;
+    Rc::new(maps)
+}
+
+pub fn provide(providers: &mut Providers) {
+    *providers = Providers {
+        region_resolve_crate,
+        ..*providers
+    };
 }
diff --git a/src/librustc/traits/object_safety.rs b/src/librustc/traits/object_safety.rs
index 351bde2177c..98b502f5608 100644
--- a/src/librustc/traits/object_safety.rs
+++ b/src/librustc/traits/object_safety.rs
@@ -207,7 +207,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
 
         // Search for a predicate like `Self : Sized` amongst the trait bounds.
         let free_substs = self.construct_free_substs(def_id,
-            self.region_maps.node_extent(ast::DUMMY_NODE_ID));
+            self.region_maps().node_extent(ast::DUMMY_NODE_ID));
         let predicates = self.predicates_of(def_id);
         let predicates = predicates.instantiate(self, free_substs).predicates;
         elaborate_predicates(self, predicates)
diff --git a/src/librustc/ty/context.rs b/src/librustc/ty/context.rs
index ac7a72e6665..c6e9822da89 100644
--- a/src/librustc/ty/context.rs
+++ b/src/librustc/ty/context.rs
@@ -51,6 +51,7 @@ use std::mem;
 use std::ops::Deref;
 use std::iter;
 use std::cmp::Ordering;
+use std::rc::Rc;
 use syntax::abi;
 use syntax::ast::{self, Name, NodeId};
 use syntax::attr;
@@ -439,8 +440,6 @@ pub struct GlobalCtxt<'tcx> {
 
     pub named_region_map: resolve_lifetime::NamedRegionMap,
 
-    pub region_maps: RegionMaps,
-
     pub hir: hir_map::Map<'tcx>,
     pub maps: maps::Maps<'tcx>,
 
@@ -678,6 +677,10 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         local as usize == global as usize
     }
 
+    pub fn region_maps(self) -> Rc<RegionMaps> {
+        self.region_resolve_crate(LOCAL_CRATE)
+    }
+
     /// Create a type context and call the closure with a `TyCtxt` reference
     /// to the context. The closure enforces that the type context and any interned
     /// value (types, substs, etc.) can only be used while `ty::tls` has a valid
@@ -690,7 +693,6 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                                   resolutions: ty::Resolutions,
                                   named_region_map: resolve_lifetime::NamedRegionMap,
                                   hir: hir_map::Map<'tcx>,
-                                  region_maps: RegionMaps,
                                   lang_items: middle::lang_items::LanguageItems,
                                   stability: stability::Index<'tcx>,
                                   crate_name: &str,
@@ -714,7 +716,6 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
             dep_graph: dep_graph.clone(),
             types: common_types,
             named_region_map: named_region_map,
-            region_maps: region_maps,
             variance_computed: Cell::new(false),
             trait_map: resolutions.trait_map,
             export_map: resolutions.export_map,
diff --git a/src/librustc/ty/maps.rs b/src/librustc/ty/maps.rs
index 76398294aca..abee0ae4ad6 100644
--- a/src/librustc/ty/maps.rs
+++ b/src/librustc/ty/maps.rs
@@ -14,6 +14,7 @@ use hir::def::Def;
 use hir;
 use middle::const_val;
 use middle::privacy::AccessLevels;
+use middle::region::RegionMaps;
 use mir;
 use session::CompileResult;
 use ty::{self, CrateInherentImpls, Ty, TyCtxt};
@@ -291,6 +292,12 @@ impl<'tcx> QueryDescription for queries::def_span<'tcx> {
     }
 }
 
+impl<'tcx> QueryDescription for queries::region_resolve_crate<'tcx> {
+    fn describe(_: TyCtxt, _: CrateNum) -> String {
+        format!("resolve crate")
+    }
+}
+
 macro_rules! define_maps {
     (<$tcx:tt>
      $($(#[$attr:meta])*
@@ -571,6 +578,8 @@ define_maps! { <'tcx>
 
     [] reachable_set: reachability_dep_node(CrateNum) -> Rc<NodeSet>,
 
+    [] region_resolve_crate: region_resolve_crate_dep_node(CrateNum) -> Rc<RegionMaps>,
+
     [] mir_shims: mir_shim_dep_node(ty::InstanceDef<'tcx>) -> &'tcx RefCell<mir::Mir<'tcx>>,
 
     [] def_symbol_name: SymbolName(DefId) -> ty::SymbolName,
@@ -592,6 +601,10 @@ fn reachability_dep_node(_: CrateNum) -> DepNode<DefId> {
     DepNode::Reachability
 }
 
+fn region_resolve_crate_dep_node(_: CrateNum) -> DepNode<DefId> {
+    DepNode::RegionResolveCrate
+}
+
 fn mir_shim_dep_node(instance: ty::InstanceDef) -> DepNode<DefId> {
     instance.dep_node()
 }
@@ -608,4 +621,4 @@ fn typeck_item_bodies_dep_node(_: CrateNum) -> DepNode<DefId> {
 
 fn const_eval_dep_node((def_id, _): (DefId, &Substs)) -> DepNode<DefId> {
     DepNode::ConstEval(def_id)
-}
\ No newline at end of file
+}
diff --git a/src/librustc/ty/mod.rs b/src/librustc/ty/mod.rs
index 8be3e4be7c8..c0b340ad544 100644
--- a/src/librustc/ty/mod.rs
+++ b/src/librustc/ty/mod.rs
@@ -1220,13 +1220,13 @@ impl<'a, 'tcx> ParameterEnvironment<'tcx> {
                         let impl_def_id = tcx.hir.local_def_id(impl_id);
                         tcx.construct_parameter_environment(impl_item.span,
                                                             impl_def_id,
-                                                            tcx.region_maps.item_extent(id))
+                                                            tcx.region_maps().item_extent(id))
                     }
                     hir::ImplItemKind::Method(_, ref body) => {
                         tcx.construct_parameter_environment(
                             impl_item.span,
                             tcx.hir.local_def_id(id),
-                            tcx.region_maps.call_site_extent(id, body.node_id))
+                            tcx.region_maps().call_site_extent(id, body.node_id))
                     }
                 }
             }
@@ -1239,7 +1239,7 @@ impl<'a, 'tcx> ParameterEnvironment<'tcx> {
                         let trait_def_id = tcx.hir.local_def_id(trait_id);
                         tcx.construct_parameter_environment(trait_item.span,
                                                             trait_def_id,
-                                                            tcx.region_maps.item_extent(id))
+                                                            tcx.region_maps().item_extent(id))
                     }
                     hir::TraitItemKind::Method(_, ref body) => {
                         // Use call-site for extent (unless this is a
@@ -1247,10 +1247,10 @@ impl<'a, 'tcx> ParameterEnvironment<'tcx> {
                         // to the method id).
                         let extent = if let hir::TraitMethod::Provided(body_id) = *body {
                             // default impl: use call_site extent as free_id_outlive bound.
-                            tcx.region_maps.call_site_extent(id, body_id.node_id)
+                            tcx.region_maps().call_site_extent(id, body_id.node_id)
                         } else {
                             // no default impl: use item extent as free_id_outlive bound.
-                            tcx.region_maps.item_extent(id)
+                            tcx.region_maps().item_extent(id)
                         };
                         tcx.construct_parameter_environment(
                             trait_item.span,
@@ -1268,7 +1268,7 @@ impl<'a, 'tcx> ParameterEnvironment<'tcx> {
                         tcx.construct_parameter_environment(
                             item.span,
                             fn_def_id,
-                            tcx.region_maps.call_site_extent(id, body_id.node_id))
+                            tcx.region_maps().call_site_extent(id, body_id.node_id))
                     }
                     hir::ItemEnum(..) |
                     hir::ItemStruct(..) |
@@ -1280,13 +1280,13 @@ impl<'a, 'tcx> ParameterEnvironment<'tcx> {
                         let def_id = tcx.hir.local_def_id(id);
                         tcx.construct_parameter_environment(item.span,
                                                             def_id,
-                                                            tcx.region_maps.item_extent(id))
+                                                            tcx.region_maps().item_extent(id))
                     }
                     hir::ItemTrait(..) => {
                         let def_id = tcx.hir.local_def_id(id);
                         tcx.construct_parameter_environment(item.span,
                                                             def_id,
-                                                            tcx.region_maps.item_extent(id))
+                                                            tcx.region_maps().item_extent(id))
                     }
                     _ => {
                         span_bug!(item.span,
@@ -1304,7 +1304,7 @@ impl<'a, 'tcx> ParameterEnvironment<'tcx> {
                     tcx.construct_parameter_environment(
                         expr.span,
                         base_def_id,
-                        tcx.region_maps.call_site_extent(id, body.node_id))
+                        tcx.region_maps().call_site_extent(id, body.node_id))
                 } else {
                     tcx.empty_parameter_environment()
                 }
@@ -2474,7 +2474,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
     }
 
     /// See `ParameterEnvironment` struct def'n for details.
-    /// If you were using `free_id: NodeId`, you might try `self.region_maps.item_extent(free_id)`
+    /// If you were using `free_id: NodeId`, you might try `self.region_maps().item_extent(free_id)`
     /// for the `free_id_outlive` parameter. (But note that this is not always quite right.)
     pub fn construct_parameter_environment(self,
                                            span: Span,
@@ -2521,12 +2521,13 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
             is_freeze_cache: RefCell::new(FxHashMap()),
         };
 
-        let cause = traits::ObligationCause::misc(span, free_id_outlive.node_id(&self.region_maps));
+        let cause = traits::ObligationCause::misc(span,
+                                                  free_id_outlive.node_id(&self.region_maps()));
         traits::normalize_param_env_or_error(tcx, unnormalized_env, cause)
     }
 
     pub fn node_scope_region(self, id: NodeId) -> &'tcx Region {
-        self.mk_region(ty::ReScope(self.region_maps.node_extent(id)))
+        self.mk_region(ty::ReScope(self.region_maps().node_extent(id)))
     }
 
     pub fn visit_all_item_likes_in_krate<V,F>(self,