Auto merge of #44012 - michaelwoerister:cache-hir-dep-node-index, r=nikomatsakis

incr.comp.: Cache Hir-DepNodeIndices in the HIR map.

In preparation for red/green. This should also be faster than before without any additional memory cost.

r? @nikomatsakis

src/librustc/dep_graph/edges.rs

@@ -244,8 +244,8 @@ impl DepGraphEdges {
         self.edges.insert((source, target));
     }
 
-    pub fn add_node(&mut self, node: DepNode) {
+    pub fn add_node(&mut self, node: DepNode) -> DepNodeIndex {
-        self.get_or_create_node(node);
+        self.get_or_create_node(node)
     }
 
     #[inline]

src/librustc/dep_graph/graph.rs

@@ -173,6 +173,14 @@ impl DepGraph {
         self.data.as_ref().unwrap().edges.borrow_mut().add_node(node);
     }
 
+    pub fn alloc_input_node(&self, node: DepNode) -> DepNodeIndex {
+        if let Some(ref data) = self.data {
+            data.edges.borrow_mut().add_node(node)
+        } else {
+            DepNodeIndex::INVALID
+        }
+    }
+
     /// Indicates that a previous work product exists for `v`. This is
     /// invoked during initial start-up based on what nodes are clean
     /// (and what files exist in the incr. directory).

src/librustc/hir/intravisit.rs

@@ -827,7 +827,16 @@ pub fn walk_trait_item_ref<'v, V: Visitor<'v>>(visitor: &mut V, trait_item_ref:
 
 pub fn walk_impl_item<'v, V: Visitor<'v>>(visitor: &mut V, impl_item: &'v ImplItem) {
     // NB: Deliberately force a compilation error if/when new fields are added.
-    let ImplItem { id: _, name, ref vis, ref defaultness, ref attrs, ref node, span } = *impl_item;
+    let ImplItem {
+        id: _,
+        hir_id: _,
+        name,
+        ref vis,
+        ref defaultness,
+        ref attrs,
+        ref node,
+        span
+    } = *impl_item;
 
     visitor.visit_name(span, name);
     visitor.visit_vis(vis);

src/librustc/hir/lowering.rs

@@ -1315,7 +1315,12 @@ impl<'a> LoweringContext<'a> {
                             path.span = span;
 
                             self.allocate_hir_id_counter(import.id, import);
-                            self.with_hir_id_owner(import.id, |this| {
+                            let LoweredNodeId {
+                                node_id: import_node_id,
+                                hir_id: import_hir_id,
+                            } = self.lower_node_id(import.id);
+
+                            self.with_hir_id_owner(import_node_id, |this| {
                                 let vis = match *vis {
                                     hir::Visibility::Public => hir::Visibility::Public,
                                     hir::Visibility::Crate => hir::Visibility::Crate,
@@ -1329,8 +1334,9 @@ impl<'a> LoweringContext<'a> {
                                     }
                                 };
 
-                                this.items.insert(import.id, hir::Item {
+                                this.items.insert(import_node_id, hir::Item {
-                                    id: import.id,
+                                    id: import_node_id,
+                                    hir_id: import_hir_id,
                                     name: import.rename.unwrap_or(ident).name,
                                     attrs: attrs.clone(),
                                     node: hir::ItemUse(P(path), hir::UseKind::Single),
@@ -1461,8 +1467,11 @@ impl<'a> LoweringContext<'a> {
 
     fn lower_trait_item(&mut self, i: &TraitItem) -> hir::TraitItem {
         self.with_parent_def(i.id, |this| {
+            let LoweredNodeId { node_id, hir_id } = this.lower_node_id(i.id);
+
             hir::TraitItem {
-                id: this.lower_node_id(i.id).node_id,
+                id: node_id,
+                hir_id,
                 name: this.lower_ident(i.ident),
                 attrs: this.lower_attrs(&i.attrs),
                 node: match i.node {
@@ -1522,8 +1531,11 @@ impl<'a> LoweringContext<'a> {
 
     fn lower_impl_item(&mut self, i: &ImplItem) -> hir::ImplItem {
         self.with_parent_def(i.id, |this| {
+            let LoweredNodeId { node_id, hir_id } = this.lower_node_id(i.id);
+
             hir::ImplItem {
-                id: this.lower_node_id(i.id).node_id,
+                id: node_id,
+                hir_id,
                 name: this.lower_ident(i.ident),
                 attrs: this.lower_attrs(&i.attrs),
                 vis: this.lower_visibility(&i.vis, None),
@@ -1614,8 +1626,11 @@ impl<'a> LoweringContext<'a> {
             this.lower_item_kind(i.id, &mut name, &attrs, &mut vis, &i.node)
         });
 
+        let LoweredNodeId { node_id, hir_id } = self.lower_node_id(i.id);
+
         Some(hir::Item {
-            id: self.lower_node_id(i.id).node_id,
+            id: node_id,
+            hir_id,
             name,
             attrs,
             node,

src/librustc/hir/map/collector.rs

@@ -10,33 +10,55 @@
 
 use super::*;
 
+use dep_graph::{DepGraph, DepKind, DepNodeIndex};
 use hir::intravisit::{Visitor, NestedVisitorMap};
 use std::iter::repeat;
 use syntax::ast::{NodeId, CRATE_NODE_ID};
 use syntax_pos::Span;
 
 /// A Visitor that walks over the HIR and collects Nodes into a HIR map
-pub struct NodeCollector<'hir> {
+pub(super) struct NodeCollector<'a, 'hir> {
     /// The crate
-    pub krate: &'hir Crate,
+    krate: &'hir Crate,
     /// The node map
-    pub(super) map: Vec<MapEntry<'hir>>,
+    map: Vec<MapEntry<'hir>>,
     /// The parent of this node
-    pub parent_node: NodeId,
+    parent_node: NodeId,
+
+    current_dep_node_owner: DefIndex,
+    current_dep_node_index: DepNodeIndex,
+
+    dep_graph: &'a DepGraph,
+    definitions: &'a definitions::Definitions,
 }
 
-impl<'hir> NodeCollector<'hir> {
+impl<'a, 'hir> NodeCollector<'a, 'hir> {
-    pub fn root(krate: &'hir Crate) -> NodeCollector<'hir> {
+    pub(super) fn root(krate: &'hir Crate,
+                dep_graph: &'a DepGraph,
+                definitions: &'a definitions::Definitions)
+                -> NodeCollector<'a, 'hir> {
+        let root_mod_def_path_hash = definitions.def_path_hash(CRATE_DEF_INDEX);
+        let root_mod_dep_node = root_mod_def_path_hash.to_dep_node(DepKind::Hir);
+        let root_mod_dep_node_index = dep_graph.alloc_input_node(root_mod_dep_node);
+
         let mut collector = NodeCollector {
             krate,
             map: vec![],
             parent_node: CRATE_NODE_ID,
+            current_dep_node_index: root_mod_dep_node_index,
+            current_dep_node_owner: CRATE_DEF_INDEX,
+            dep_graph,
+            definitions,
         };
-        collector.insert_entry(CRATE_NODE_ID, RootCrate);
+        collector.insert_entry(CRATE_NODE_ID, RootCrate(root_mod_dep_node_index));
 
         collector
     }
 
+    pub(super) fn into_map(self) -> Vec<MapEntry<'hir>> {
+        self.map
+    }
+
     fn insert_entry(&mut self, id: NodeId, entry: MapEntry<'hir>) {
         debug!("hir_map: {:?} => {:?}", id, entry);
         let len = self.map.len();
@@ -47,8 +69,55 @@ impl<'hir> NodeCollector<'hir> {
     }
 
     fn insert(&mut self, id: NodeId, node: Node<'hir>) {
-        let entry = MapEntry::from_node(self.parent_node, node);
+        let parent = self.parent_node;
+        let dep_node_index = self.current_dep_node_index;
+
+        let entry = match node {
+            NodeItem(n) => EntryItem(parent, dep_node_index, n),
+            NodeForeignItem(n) => EntryForeignItem(parent, dep_node_index, n),
+            NodeTraitItem(n) => EntryTraitItem(parent, dep_node_index, n),
+            NodeImplItem(n) => EntryImplItem(parent, dep_node_index, n),
+            NodeVariant(n) => EntryVariant(parent, dep_node_index, n),
+            NodeField(n) => EntryField(parent, dep_node_index, n),
+            NodeExpr(n) => EntryExpr(parent, dep_node_index, n),
+            NodeStmt(n) => EntryStmt(parent, dep_node_index, n),
+            NodeTy(n) => EntryTy(parent, dep_node_index, n),
+            NodeTraitRef(n) => EntryTraitRef(parent, dep_node_index, n),
+            NodeBinding(n) => EntryBinding(parent, dep_node_index, n),
+            NodePat(n) => EntryPat(parent, dep_node_index, n),
+            NodeBlock(n) => EntryBlock(parent, dep_node_index, n),
+            NodeStructCtor(n) => EntryStructCtor(parent, dep_node_index, n),
+            NodeLifetime(n) => EntryLifetime(parent, dep_node_index, n),
+            NodeTyParam(n) => EntryTyParam(parent, dep_node_index, n),
+            NodeVisibility(n) => EntryVisibility(parent, dep_node_index, n),
+            NodeLocal(n) => EntryLocal(parent, dep_node_index, n),
+        };
+
+        // Make sure that the DepNode of some node coincides with the HirId
+        // owner of that node.
+        if cfg!(debug_assertions) {
+            let hir_id_owner = self.definitions.node_to_hir_id(id).owner;
+
+            if hir_id_owner != self.current_dep_node_owner {
+                let node_str = match self.definitions.opt_def_index(id) {
+                    Some(def_index) => {
+                        self.definitions.def_path(def_index).to_string_no_crate()
+                    }
+                    None => format!("{:?}", node)
+                };
+
+                bug!("inconsistent DepNode for `{}`: \
+                      current_dep_node_owner={}, hir_id.owner={}",
+                    node_str,
+                    self.definitions
+                        .def_path(self.current_dep_node_owner)
+                        .to_string_no_crate(),
+                    self.definitions.def_path(hir_id_owner).to_string_no_crate())
+            }
+        }
+
         self.insert_entry(id, entry);
+
     }
 
     fn with_parent<F: FnOnce(&mut Self)>(&mut self, parent_id: NodeId, f: F) {
@@ -57,9 +126,27 @@ impl<'hir> NodeCollector<'hir> {
         f(self);
         self.parent_node = parent_node;
     }
+
+    fn with_dep_node_owner<F: FnOnce(&mut Self)>(&mut self,
+                                                 dep_node_owner: DefIndex,
+                                                 f: F) {
+        let prev_owner = self.current_dep_node_owner;
+        let prev_index = self.current_dep_node_index;
+
+        // When we enter a new owner (item, impl item, or trait item), we always
+        // start out again with DepKind::Hir.
+        let new_dep_node = self.definitions
+                               .def_path_hash(dep_node_owner)
+                               .to_dep_node(DepKind::Hir);
+        self.current_dep_node_index = self.dep_graph.alloc_input_node(new_dep_node);
+        self.current_dep_node_owner = dep_node_owner;
+        f(self);
+        self.current_dep_node_index = prev_index;
+        self.current_dep_node_owner = prev_owner;
+    }
 }
 
-impl<'hir> Visitor<'hir> for NodeCollector<'hir> {
+impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> {
     /// Because we want to track parent items and so forth, enable
     /// deep walking so that we walk nested items in the context of
     /// their outer items.
@@ -82,25 +169,37 @@ impl<'hir> Visitor<'hir> for NodeCollector<'hir> {
     }
 
     fn visit_nested_body(&mut self, id: BodyId) {
+        // When we enter a body, we switch to DepKind::HirBody.
+        // Note that current_dep_node_index might already be DepKind::HirBody,
+        // e.g. when entering the body of a closure that is already part of a
+        // surrounding body. That's expected and not a problem.
+        let prev_index = self.current_dep_node_index;
+        let new_dep_node = self.definitions
+                               .def_path_hash(self.current_dep_node_owner)
+                               .to_dep_node(DepKind::HirBody);
+        self.current_dep_node_index = self.dep_graph.alloc_input_node(new_dep_node);
         self.visit_body(self.krate.body(id));
+        self.current_dep_node_index = prev_index;
     }
 
     fn visit_item(&mut self, i: &'hir Item) {
         debug!("visit_item: {:?}", i);
-
+        debug_assert_eq!(i.hir_id.owner,
-        self.insert(i.id, NodeItem(i));
+                         self.definitions.opt_def_index(i.id).unwrap());
-
+        self.with_dep_node_owner(i.hir_id.owner, |this| {
-        self.with_parent(i.id, |this| {
+            this.insert(i.id, NodeItem(i));
-            match i.node {
+            this.with_parent(i.id, |this| {
-                ItemStruct(ref struct_def, _) => {
+                match i.node {
-                    // If this is a tuple-like struct, register the constructor.
+                    ItemStruct(ref struct_def, _) => {
-                    if !struct_def.is_struct() {
+                        // If this is a tuple-like struct, register the constructor.
-                        this.insert(struct_def.id(), NodeStructCtor(struct_def));
+                        if !struct_def.is_struct() {
+                            this.insert(struct_def.id(), NodeStructCtor(struct_def));
+                        }
                     }
+                    _ => {}
                 }
-                _ => {}
+                intravisit::walk_item(this, i);
-            }
+            });
-            intravisit::walk_item(this, i);
         });
     }
 
@@ -121,18 +220,26 @@ impl<'hir> Visitor<'hir> for NodeCollector<'hir> {
     }
 
     fn visit_trait_item(&mut self, ti: &'hir TraitItem) {
-        self.insert(ti.id, NodeTraitItem(ti));
+        debug_assert_eq!(ti.hir_id.owner,
+                         self.definitions.opt_def_index(ti.id).unwrap());
+        self.with_dep_node_owner(ti.hir_id.owner, |this| {
+            this.insert(ti.id, NodeTraitItem(ti));
 
-        self.with_parent(ti.id, |this| {
+            this.with_parent(ti.id, |this| {
-            intravisit::walk_trait_item(this, ti);
+                intravisit::walk_trait_item(this, ti);
+            });
         });
     }
 
     fn visit_impl_item(&mut self, ii: &'hir ImplItem) {
-        self.insert(ii.id, NodeImplItem(ii));
+        debug_assert_eq!(ii.hir_id.owner,
+                         self.definitions.opt_def_index(ii.id).unwrap());
+        self.with_dep_node_owner(ii.hir_id.owner, |this| {
+            this.insert(ii.id, NodeImplItem(ii));
 
-        self.with_parent(ii.id, |this| {
+            this.with_parent(ii.id, |this| {
-            intravisit::walk_impl_item(this, ii);
+                intravisit::walk_impl_item(this, ii);
+            });
         });
     }
 
@@ -238,4 +345,33 @@ impl<'hir> Visitor<'hir> for NodeCollector<'hir> {
             intravisit::walk_struct_field(this, field);
         });
     }
+
+    fn visit_trait_item_ref(&mut self, ii: &'hir TraitItemRef) {
+        // Do not visit the duplicate information in TraitItemRef. We want to
+        // map the actual nodes, not the duplicate ones in the *Ref.
+        let TraitItemRef {
+            id,
+            name: _,
+            kind: _,
+            span: _,
+            defaultness: _,
+        } = *ii;
+
+        self.visit_nested_trait_item(id);
+    }
+
+    fn visit_impl_item_ref(&mut self, ii: &'hir ImplItemRef) {
+        // Do not visit the duplicate information in ImplItemRef. We want to
+        // map the actual nodes, not the duplicate ones in the *Ref.
+        let ImplItemRef {
+            id,
+            name: _,
+            kind: _,
+            span: _,
+            vis: _,
+            defaultness: _,
+        } = *ii;
+
+        self.visit_nested_impl_item(id);
+    }
 }

src/librustc/hir/map/mod.rs

@@ -15,7 +15,7 @@ pub use self::def_collector::{DefCollector, MacroInvocationData};
 pub use self::definitions::{Definitions, DefKey, DefPath, DefPathData,
                             DisambiguatedDefPathData, DefPathHash};
 
-use dep_graph::{DepGraph, DepNode, DepKind};
+use dep_graph::{DepGraph, DepNode, DepKind, DepNodeIndex};
 
 use hir::def_id::{CRATE_DEF_INDEX, DefId, DefIndexAddressSpace};
 
@@ -74,27 +74,28 @@ enum MapEntry<'hir> {
     NotPresent,
 
     /// All the node types, with a parent ID.
-    EntryItem(NodeId, &'hir Item),
+    EntryItem(NodeId, DepNodeIndex, &'hir Item),
-    EntryForeignItem(NodeId, &'hir ForeignItem),
+    EntryForeignItem(NodeId, DepNodeIndex, &'hir ForeignItem),
-    EntryTraitItem(NodeId, &'hir TraitItem),
+    EntryTraitItem(NodeId, DepNodeIndex, &'hir TraitItem),
-    EntryImplItem(NodeId, &'hir ImplItem),
+    EntryImplItem(NodeId, DepNodeIndex, &'hir ImplItem),
-    EntryVariant(NodeId, &'hir Variant),
+    EntryVariant(NodeId, DepNodeIndex, &'hir Variant),
-    EntryField(NodeId, &'hir StructField),
+    EntryField(NodeId, DepNodeIndex, &'hir StructField),
-    EntryExpr(NodeId, &'hir Expr),
+    EntryExpr(NodeId, DepNodeIndex, &'hir Expr),
-    EntryStmt(NodeId, &'hir Stmt),
+    EntryStmt(NodeId, DepNodeIndex, &'hir Stmt),
-    EntryTy(NodeId, &'hir Ty),
+    EntryTy(NodeId, DepNodeIndex, &'hir Ty),
-    EntryTraitRef(NodeId, &'hir TraitRef),
+    EntryTraitRef(NodeId, DepNodeIndex, &'hir TraitRef),
-    EntryBinding(NodeId, &'hir Pat),
+    EntryBinding(NodeId, DepNodeIndex, &'hir Pat),
-    EntryPat(NodeId, &'hir Pat),
+    EntryPat(NodeId, DepNodeIndex, &'hir Pat),
-    EntryBlock(NodeId, &'hir Block),
+    EntryBlock(NodeId, DepNodeIndex, &'hir Block),
-    EntryStructCtor(NodeId, &'hir VariantData),
+    EntryStructCtor(NodeId, DepNodeIndex, &'hir VariantData),
-    EntryLifetime(NodeId, &'hir Lifetime),
+    EntryLifetime(NodeId, DepNodeIndex, &'hir Lifetime),
-    EntryTyParam(NodeId, &'hir TyParam),
+    EntryTyParam(NodeId, DepNodeIndex, &'hir TyParam),
-    EntryVisibility(NodeId, &'hir Visibility),
+    EntryVisibility(NodeId, DepNodeIndex, &'hir Visibility),
-    EntryLocal(NodeId, &'hir Local),
+    EntryLocal(NodeId, DepNodeIndex, &'hir Local),
 
-    /// Roots for node trees.
+    /// Roots for node trees. The DepNodeIndex is the dependency node of the
-    RootCrate,
+    /// crate's root module.
+    RootCrate(DepNodeIndex),
 }
 
 impl<'hir> Clone for MapEntry<'hir> {
@@ -104,82 +105,59 @@ impl<'hir> Clone for MapEntry<'hir> {
 }
 
 impl<'hir> MapEntry<'hir> {
-    fn from_node(p: NodeId, node: Node<'hir>) -> MapEntry<'hir> {
-        match node {
-            NodeItem(n) => EntryItem(p, n),
-            NodeForeignItem(n) => EntryForeignItem(p, n),
-            NodeTraitItem(n) => EntryTraitItem(p, n),
-            NodeImplItem(n) => EntryImplItem(p, n),
-            NodeVariant(n) => EntryVariant(p, n),
-            NodeField(n) => EntryField(p, n),
-            NodeExpr(n) => EntryExpr(p, n),
-            NodeStmt(n) => EntryStmt(p, n),
-            NodeTy(n) => EntryTy(p, n),
-            NodeTraitRef(n) => EntryTraitRef(p, n),
-            NodeBinding(n) => EntryBinding(p, n),
-            NodePat(n) => EntryPat(p, n),
-            NodeBlock(n) => EntryBlock(p, n),
-            NodeStructCtor(n) => EntryStructCtor(p, n),
-            NodeLifetime(n) => EntryLifetime(p, n),
-            NodeTyParam(n) => EntryTyParam(p, n),
-            NodeVisibility(n) => EntryVisibility(p, n),
-            NodeLocal(n) => EntryLocal(p, n),
-        }
-    }
-
     fn parent_node(self) -> Option<NodeId> {
         Some(match self {
-            EntryItem(id, _) => id,
+            EntryItem(id, _, _) => id,
-            EntryForeignItem(id, _) => id,
+            EntryForeignItem(id, _, _) => id,
-            EntryTraitItem(id, _) => id,
+            EntryTraitItem(id, _, _) => id,
-            EntryImplItem(id, _) => id,
+            EntryImplItem(id, _, _) => id,
-            EntryVariant(id, _) => id,
+            EntryVariant(id, _, _) => id,
-            EntryField(id, _) => id,
+            EntryField(id, _, _) => id,
-            EntryExpr(id, _) => id,
+            EntryExpr(id, _, _) => id,
-            EntryStmt(id, _) => id,
+            EntryStmt(id, _, _) => id,
-            EntryTy(id, _) => id,
+            EntryTy(id, _, _) => id,
-            EntryTraitRef(id, _) => id,
+            EntryTraitRef(id, _, _) => id,
-            EntryBinding(id, _) => id,
+            EntryBinding(id, _, _) => id,
-            EntryPat(id, _) => id,
+            EntryPat(id, _, _) => id,
-            EntryBlock(id, _) => id,
+            EntryBlock(id, _, _) => id,
-            EntryStructCtor(id, _) => id,
+            EntryStructCtor(id, _, _) => id,
-            EntryLifetime(id, _) => id,
+            EntryLifetime(id, _, _) => id,
-            EntryTyParam(id, _) => id,
+            EntryTyParam(id, _, _) => id,
-            EntryVisibility(id, _) => id,
+            EntryVisibility(id, _, _) => id,
-            EntryLocal(id, _) => id,
+            EntryLocal(id, _, _) => id,
 
             NotPresent |
-            RootCrate => return None,
+            RootCrate(_) => return None,
         })
     }
 
     fn to_node(self) -> Option<Node<'hir>> {
         Some(match self {
-            EntryItem(_, n) => NodeItem(n),
+            EntryItem(_, _, n) => NodeItem(n),
-            EntryForeignItem(_, n) => NodeForeignItem(n),
+            EntryForeignItem(_, _, n) => NodeForeignItem(n),
-            EntryTraitItem(_, n) => NodeTraitItem(n),
+            EntryTraitItem(_, _, n) => NodeTraitItem(n),
-            EntryImplItem(_, n) => NodeImplItem(n),
+            EntryImplItem(_, _, n) => NodeImplItem(n),
-            EntryVariant(_, n) => NodeVariant(n),
+            EntryVariant(_, _, n) => NodeVariant(n),
-            EntryField(_, n) => NodeField(n),
+            EntryField(_, _, n) => NodeField(n),
-            EntryExpr(_, n) => NodeExpr(n),
+            EntryExpr(_, _, n) => NodeExpr(n),
-            EntryStmt(_, n) => NodeStmt(n),
+            EntryStmt(_, _, n) => NodeStmt(n),
-            EntryTy(_, n) => NodeTy(n),
+            EntryTy(_, _, n) => NodeTy(n),
-            EntryTraitRef(_, n) => NodeTraitRef(n),
+            EntryTraitRef(_, _, n) => NodeTraitRef(n),
-            EntryBinding(_, n) => NodeBinding(n),
+            EntryBinding(_, _, n) => NodeBinding(n),
-            EntryPat(_, n) => NodePat(n),
+            EntryPat(_, _, n) => NodePat(n),
-            EntryBlock(_, n) => NodeBlock(n),
+            EntryBlock(_, _, n) => NodeBlock(n),
-            EntryStructCtor(_, n) => NodeStructCtor(n),
+            EntryStructCtor(_, _, n) => NodeStructCtor(n),
-            EntryLifetime(_, n) => NodeLifetime(n),
+            EntryLifetime(_, _, n) => NodeLifetime(n),
-            EntryTyParam(_, n) => NodeTyParam(n),
+            EntryTyParam(_, _, n) => NodeTyParam(n),
-            EntryVisibility(_, n) => NodeVisibility(n),
+            EntryVisibility(_, _, n) => NodeVisibility(n),
-            EntryLocal(_, n) => NodeLocal(n),
+            EntryLocal(_, _, n) => NodeLocal(n),
             _ => return None
         })
     }
 
     fn associated_body(self) -> Option<BodyId> {
         match self {
-            EntryItem(_, item) => {
+            EntryItem(_, _, item) => {
                 match item.node {
                     ItemConst(_, body) |
                     ItemStatic(.., body) |
@@ -188,7 +166,7 @@ impl<'hir> MapEntry<'hir> {
                 }
             }
 
-            EntryTraitItem(_, item) => {
+            EntryTraitItem(_, _, item) => {
                 match item.node {
                     TraitItemKind::Const(_, Some(body)) |
                     TraitItemKind::Method(_, TraitMethod::Provided(body)) => Some(body),
@@ -196,7 +174,7 @@ impl<'hir> MapEntry<'hir> {
                 }
             }
 
-            EntryImplItem(_, item) => {
+            EntryImplItem(_, _, item) => {
                 match item.node {
                     ImplItemKind::Const(_, body) |
                     ImplItemKind::Method(_, body) => Some(body),
@@ -204,7 +182,7 @@ impl<'hir> MapEntry<'hir> {
                 }
             }
 
-            EntryExpr(_, expr) => {
+            EntryExpr(_, _, expr) => {
                 match expr.node {
                     ExprClosure(.., body, _) => Some(body),
                     _ => None,
@@ -282,83 +260,40 @@ impl<'hir> Map<'hir> {
     /// read recorded). If the function just returns a DefId or
     /// NodeId, no actual content was returned, so no read is needed.
     pub fn read(&self, id: NodeId) {
-        self.dep_graph.read(self.dep_node(id));
+        let entry = self.map[id.as_usize()];
-    }
+        match entry {
-
+            EntryItem(_, dep_node_index, _) |
-    fn dep_node(&self, id0: NodeId) -> DepNode {
+            EntryTraitItem(_, dep_node_index, _) |
-        let mut id = id0;
+            EntryImplItem(_, dep_node_index, _) |
-        let mut last_expr = None;
+            EntryVariant(_, dep_node_index, _) |
-        loop {
+            EntryForeignItem(_, dep_node_index, _) |
-            let entry = self.map[id.as_usize()];
+            EntryField(_, dep_node_index, _) |
-            match entry {
+            EntryStmt(_, dep_node_index, _) |
-                EntryItem(..) |
+            EntryTy(_, dep_node_index, _) |
-                EntryTraitItem(..) |
+            EntryTraitRef(_, dep_node_index, _) |
-                EntryImplItem(..) => {
+            EntryBinding(_, dep_node_index, _) |
-                    let def_index = self.definitions.opt_def_index(id).unwrap();
+            EntryPat(_, dep_node_index, _) |
+            EntryBlock(_, dep_node_index, _) |
+            EntryStructCtor(_, dep_node_index, _) |
+            EntryLifetime(_, dep_node_index, _) |
+            EntryTyParam(_, dep_node_index, _) |
+            EntryVisibility(_, dep_node_index, _) |
+            EntryExpr(_, dep_node_index, _) |
+            EntryLocal(_, dep_node_index, _) |
+            RootCrate(dep_node_index) => {
+                self.dep_graph.read_index(dep_node_index);
+            }
+            NotPresent => {
+                // Some nodes, notably macro definitions, are not
+                // present in the map for whatever reason, but
+                // they *do* have def-ids. So if we encounter an
+                // empty hole, check for that case.
+                if let Some(def_index) = self.definitions.opt_def_index(id) {
                     let def_path_hash = self.definitions.def_path_hash(def_index);
-
+                    self.dep_graph.read(def_path_hash.to_dep_node(DepKind::Hir));
-                    if let Some(last_id) = last_expr {
+                } else {
-                        // The body may have a separate dep node
+                    bug!("called HirMap::read() with invalid NodeId")
-                        if entry.is_body_owner(last_id) {
-                            return def_path_hash.to_dep_node(DepKind::HirBody);
-                        }
-                    }
-                    return def_path_hash.to_dep_node(DepKind::Hir);
                 }
-
-                EntryVariant(p, v) => {
-                    id = p;
-
-                    if last_expr.is_some() {
-                        if v.node.disr_expr.map(|e| e.node_id) == last_expr {
-                            // The enum parent holds both Hir and HirBody nodes.
-                            let def_index = self.definitions.opt_def_index(id).unwrap();
-                            let def_path_hash = self.definitions.def_path_hash(def_index);
-                            return def_path_hash.to_dep_node(DepKind::HirBody);
-                        }
-                    }
-                }
-
-                EntryForeignItem(p, _) |
-                EntryField(p, _) |
-                EntryStmt(p, _) |
-                EntryTy(p, _) |
-                EntryTraitRef(p, _) |
-                EntryBinding(p, _) |
-                EntryPat(p, _) |
-                EntryBlock(p, _) |
-                EntryStructCtor(p, _) |
-                EntryLifetime(p, _) |
-                EntryTyParam(p, _) |
-                EntryVisibility(p, _) |
-                EntryLocal(p, _) =>
-                    id = p,
-
-                EntryExpr(p, _) => {
-                    last_expr = Some(id);
-                    id = p;
-                }
-
-                RootCrate => {
-                    let def_path_hash = self.definitions.def_path_hash(CRATE_DEF_INDEX);
-                    return def_path_hash.to_dep_node(DepKind::Hir);
-                }
-
-                NotPresent =>
-                    // Some nodes, notably macro definitions, are not
-                    // present in the map for whatever reason, but
-                    // they *do* have def-ids. So if we encounter an
-                    // empty hole, check for that case.
-                    return self.definitions.opt_def_index(id)
-                               .map(|def_index| {
-                                    let def_path_hash = self.definitions.def_path_hash(def_index);
-                                    def_path_hash.to_dep_node(DepKind::Hir)
-                                })
-                               .unwrap_or_else(|| {
-                                   bug!("Walking parents from `{}` \
-                                         led to `NotPresent` at `{}`",
-                                        id0, id)
-                               }),
             }
         }
     }
@@ -481,7 +416,7 @@ impl<'hir> Map<'hir> {
                 Some(body_id)
             } else {
                 // For some expressions, the expression is its own body.
-                if let EntryExpr(_, expr) = entry {
+                if let EntryExpr(_, _, expr) = entry {
                     Some(BodyId { node_id: expr.id })
                 } else {
                     None
@@ -760,7 +695,7 @@ impl<'hir> Map<'hir> {
     pub fn get_foreign_abi(&self, id: NodeId) -> Abi {
         let parent = self.get_parent(id);
         let abi = match self.find_entry(parent) {
-            Some(EntryItem(_, i)) => {
+            Some(EntryItem(_, _, i)) => {
                 match i.node {
                     ItemForeignMod(ref nm) => Some(nm.abi),
                     _ => None
@@ -911,27 +846,27 @@ impl<'hir> Map<'hir> {
     pub fn span(&self, id: NodeId) -> Span {
         self.read(id); // reveals span from node
         match self.find_entry(id) {
-            Some(EntryItem(_, item)) => item.span,
+            Some(EntryItem(_, _, item)) => item.span,
-            Some(EntryForeignItem(_, foreign_item)) => foreign_item.span,
+            Some(EntryForeignItem(_, _, foreign_item)) => foreign_item.span,
-            Some(EntryTraitItem(_, trait_method)) => trait_method.span,
+            Some(EntryTraitItem(_, _, trait_method)) => trait_method.span,
-            Some(EntryImplItem(_, impl_item)) => impl_item.span,
+            Some(EntryImplItem(_, _, impl_item)) => impl_item.span,
-            Some(EntryVariant(_, variant)) => variant.span,
+            Some(EntryVariant(_, _, variant)) => variant.span,
-            Some(EntryField(_, field)) => field.span,
+            Some(EntryField(_, _, field)) => field.span,
-            Some(EntryExpr(_, expr)) => expr.span,
+            Some(EntryExpr(_, _, expr)) => expr.span,
-            Some(EntryStmt(_, stmt)) => stmt.span,
+            Some(EntryStmt(_, _, stmt)) => stmt.span,
-            Some(EntryTy(_, ty)) => ty.span,
+            Some(EntryTy(_, _, ty)) => ty.span,
-            Some(EntryTraitRef(_, tr)) => tr.path.span,
+            Some(EntryTraitRef(_, _, tr)) => tr.path.span,
-            Some(EntryBinding(_, pat)) => pat.span,
+            Some(EntryBinding(_, _, pat)) => pat.span,
-            Some(EntryPat(_, pat)) => pat.span,
+            Some(EntryPat(_, _, pat)) => pat.span,
-            Some(EntryBlock(_, block)) => block.span,
+            Some(EntryBlock(_, _, block)) => block.span,
-            Some(EntryStructCtor(_, _)) => self.expect_item(self.get_parent(id)).span,
+            Some(EntryStructCtor(_, _, _)) => self.expect_item(self.get_parent(id)).span,
-            Some(EntryLifetime(_, lifetime)) => lifetime.span,
+            Some(EntryLifetime(_, _, lifetime)) => lifetime.span,
-            Some(EntryTyParam(_, ty_param)) => ty_param.span,
+            Some(EntryTyParam(_, _, ty_param)) => ty_param.span,
-            Some(EntryVisibility(_, &Visibility::Restricted { ref path, .. })) => path.span,
+            Some(EntryVisibility(_, _, &Visibility::Restricted { ref path, .. })) => path.span,
-            Some(EntryVisibility(_, v)) => bug!("unexpected Visibility {:?}", v),
+            Some(EntryVisibility(_, _, v)) => bug!("unexpected Visibility {:?}", v),
-            Some(EntryLocal(_, local)) => local.span,
+            Some(EntryLocal(_, _, local)) => local.span,
 
-            Some(RootCrate) => self.forest.krate.span,
+            Some(RootCrate(_)) => self.forest.krate.span,
             Some(NotPresent) | None => {
                 bug!("hir::map::Map::span: id not in map: {:?}", id)
             }
@@ -1029,12 +964,12 @@ impl<'a, 'hir> Iterator for NodesMatchingSuffix<'a, 'hir> {
             }
             self.idx = NodeId::from_u32(self.idx.as_u32() + 1);
             let name = match self.map.find_entry(idx) {
-                Some(EntryItem(_, n))       => n.name(),
+                Some(EntryItem(_, _, n))       => n.name(),
-                Some(EntryForeignItem(_, n))=> n.name(),
+                Some(EntryForeignItem(_, _, n))=> n.name(),
-                Some(EntryTraitItem(_, n))  => n.name(),
+                Some(EntryTraitItem(_, _, n))  => n.name(),
-                Some(EntryImplItem(_, n))   => n.name(),
+                Some(EntryImplItem(_, _, n))   => n.name(),
-                Some(EntryVariant(_, n))    => n.name(),
+                Some(EntryVariant(_, _, n))    => n.name(),
-                Some(EntryField(_, n))      => n.name(),
+                Some(EntryField(_, _, n))      => n.name(),
                 _ => continue,
             };
             if self.matches_names(self.map.get_parent(idx), name) {
@@ -1060,9 +995,13 @@ impl Named for ImplItem { fn name(&self) -> Name { self.name } }
 pub fn map_crate<'hir>(forest: &'hir mut Forest,
                        definitions: Definitions)
                        -> Map<'hir> {
-    let mut collector = NodeCollector::root(&forest.krate);
+    let map = {
-    intravisit::walk_crate(&mut collector, &forest.krate);
+        let mut collector = NodeCollector::root(&forest.krate,
-    let map = collector.map;
+                                                &forest.dep_graph,
+                                                &definitions);
+        intravisit::walk_crate(&mut collector, &forest.krate);
+        collector.into_map()
+    };
 
     if log_enabled!(::log::LogLevel::Debug) {
         // This only makes sense for ordered stores; note the

src/librustc/hir/mod.rs

@@ -1220,6 +1220,7 @@ pub struct TraitItemId {
 pub struct TraitItem {
     pub id: NodeId,
     pub name: Name,
+    pub hir_id: HirId,
     pub attrs: HirVec<Attribute>,
     pub node: TraitItemKind,
     pub span: Span,
@@ -1261,6 +1262,7 @@ pub struct ImplItemId {
 pub struct ImplItem {
     pub id: NodeId,
     pub name: Name,
+    pub hir_id: HirId,
     pub vis: Visibility,
     pub defaultness: Defaultness,
     pub attrs: HirVec<Attribute>,
@@ -1667,8 +1669,9 @@ pub struct ItemId {
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 pub struct Item {
     pub name: Name,
-    pub attrs: HirVec<Attribute>,
     pub id: NodeId,
+    pub hir_id: HirId,
+    pub attrs: HirVec<Attribute>,
     pub node: Item_,
     pub vis: Visibility,
     pub span: Span,

src/librustc/ich/impls_hir.rs

@@ -731,6 +731,7 @@ impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for hir::T
                                           hasher: &mut StableHasher<W>) {
         let hir::TraitItem {
             id,
+            hir_id: _,
             name,
             ref attrs,
             ref node,
@@ -764,6 +765,7 @@ impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for hir::I
                                           hasher: &mut StableHasher<W>) {
         let hir::ImplItem {
             id,
+            hir_id: _,
             name,
             ref vis,
             defaultness,
@@ -920,6 +922,7 @@ impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for hir::I
             name,
             ref attrs,
             id,
+            hir_id: _,
             ref node,
             ref vis,
             span