Rollup merge of #39927 - nikomatsakis:incr-comp-skip-borrowck-2, r=eddyb

transition borrowck to visit all **bodies** and not item-likes

This is a better structure for incremental compilation and also more compatible with the eventual borrowck mir. It also fixes #38520 as a drive-by fix.

r? @eddyb

Author: frewsxcv

src/librustc/cfg/construct.rs

@@ -32,7 +32,7 @@ struct LoopScope {
 }
 
 pub fn construct<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
-                           body: &hir::Expr) -> CFG {
+                           body: &hir::Body) -> CFG {
     let mut graph = graph::Graph::new();
     let entry = graph.add_node(CFGNodeData::Entry);
 
@@ -43,26 +43,18 @@ pub fn construct<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     let fn_exit = graph.add_node(CFGNodeData::Exit);
     let body_exit;
 
-    // Find the function this expression is from.
-    let mut node_id = body.id;
-    loop {
-        let node = tcx.hir.get(node_id);
-        if hir::map::blocks::FnLikeNode::from_node(node).is_some() {
-            break;
-        }
-        let parent = tcx.hir.get_parent_node(node_id);
-        assert!(node_id != parent);
-        node_id = parent;
-    }
+    // Find the tables for this body.
+    let owner_def_id = tcx.hir.local_def_id(tcx.hir.body_owner(body.id()));
+    let tables = tcx.item_tables(owner_def_id);
 
     let mut cfg_builder = CFGBuilder {
         tcx: tcx,
-        tables: tcx.item_tables(tcx.hir.local_def_id(node_id)),
+        tables: tables,
         graph: graph,
         fn_exit: fn_exit,
         loop_scopes: Vec::new()
     };
-    body_exit = cfg_builder.expr(body, entry);
+    body_exit = cfg_builder.expr(&body.value, entry);
     cfg_builder.add_contained_edge(body_exit, fn_exit);
     let CFGBuilder {graph, ..} = cfg_builder;
     CFG {graph: graph,

src/librustc/cfg/mod.rs

@@ -59,7 +59,7 @@ pub type CFGEdge = graph::Edge<CFGEdgeData>;
 
 impl CFG {
     pub fn new<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
-                         body: &hir::Expr) -> CFG {
+                         body: &hir::Body) -> CFG {
         construct::construct(tcx, body)
     }
 

src/librustc/dep_graph/dep_node.rs

@@ -90,6 +90,7 @@ pub enum DepNode<D: Clone + Debug> {
     // things read/modify that MIR.
     Mir(D),
 
+    BorrowCheckKrate,
     BorrowCheck(D),
     RvalueCheck(D),
     Reachability,
@@ -206,6 +207,7 @@ impl<D: Clone + Debug> DepNode<D> {
 
         match *self {
             Krate => Some(Krate),
+            BorrowCheckKrate => Some(BorrowCheckKrate),
             CollectLanguageItems => Some(CollectLanguageItems),
             CheckStaticRecursion => Some(CheckStaticRecursion),
             ResolveLifetimes => Some(ResolveLifetimes),

src/librustc/dep_graph/mod.rs

@@ -25,5 +25,6 @@ pub use self::dep_node::WorkProductId;
 pub use self::graph::DepGraph;
 pub use self::graph::WorkProduct;
 pub use self::query::DepGraphQuery;
+pub use self::visit::visit_all_bodies_in_krate;
 pub use self::visit::visit_all_item_likes_in_krate;
 pub use self::raii::DepTask;

src/librustc/dep_graph/visit.rs

@@ -74,3 +74,13 @@ pub fn visit_all_item_likes_in_krate<'a, 'tcx, V, F>(tcx: TyCtxt<'a, 'tcx, 'tcx>
     };
     krate.visit_all_item_likes(&mut tracking_visitor)
 }
+
+pub fn visit_all_bodies_in_krate<'a, 'tcx, C>(tcx: TyCtxt<'a, 'tcx, 'tcx>, callback: C)
+    where C: Fn(/* body_owner */ DefId, /* body id */ hir::BodyId),
+{
+    let krate = tcx.hir.krate();
+    for &body_id in &krate.body_ids {
+        let body_owner_def_id = tcx.hir.body_owner_def_id(body_id);
+        callback(body_owner_def_id, body_id);
+    }
+}

src/librustc/hir/lowering.rs

@@ -46,7 +46,7 @@ use hir::map::definitions::DefPathData;
 use hir::def_id::{DefIndex, DefId};
 use hir::def::{Def, PathResolution};
 use session::Session;
-use util::nodemap::{DefIdMap, NodeMap, FxHashMap};
+use util::nodemap::{DefIdMap, NodeMap};
 
 use std::collections::BTreeMap;
 use std::iter;
@@ -77,7 +77,7 @@ pub struct LoweringContext<'a> {
 
     trait_items: BTreeMap<hir::TraitItemId, hir::TraitItem>,
     impl_items: BTreeMap<hir::ImplItemId, hir::ImplItem>,
-    bodies: FxHashMap<hir::BodyId, hir::Body>,
+    bodies: BTreeMap<hir::BodyId, hir::Body>,
 
     type_def_lifetime_params: DefIdMap<usize>,
 }
@@ -111,7 +111,7 @@ pub fn lower_crate(sess: &Session,
         items: BTreeMap::new(),
         trait_items: BTreeMap::new(),
         impl_items: BTreeMap::new(),
-        bodies: FxHashMap(),
+        bodies: BTreeMap::new(),
         type_def_lifetime_params: DefIdMap(),
     }.lower_crate(krate)
 }
@@ -185,6 +185,7 @@ impl<'a> LoweringContext<'a> {
         let module = self.lower_mod(&c.module);
         let attrs = self.lower_attrs(&c.attrs);
         let exported_macros = c.exported_macros.iter().map(|m| self.lower_macro_def(m)).collect();
+        let body_ids = body_ids(&self.bodies);
 
         hir::Crate {
             module: module,
@@ -195,6 +196,7 @@ impl<'a> LoweringContext<'a> {
             trait_items: self.trait_items,
             impl_items: self.impl_items,
             bodies: self.bodies,
+            body_ids: body_ids,
         }
     }
 
@@ -2408,3 +2410,11 @@ impl<'a> LoweringContext<'a> {
         }
     }
 }
+
+fn body_ids(bodies: &BTreeMap<hir::BodyId, hir::Body>) -> Vec<hir::BodyId> {
+    // Sorting by span ensures that we get things in order within a
+    // file, and also puts the files in a sensible order.
+    let mut body_ids: Vec<_> = bodies.keys().cloned().collect();
+    body_ids.sort_by_key(|b| bodies[b].value.span);
+    body_ids
+}

src/librustc/hir/map/mod.rs

@@ -168,43 +168,48 @@ impl<'hir> MapEntry<'hir> {
         })
     }
 
-    fn is_body_owner(self, node_id: NodeId) -> bool {
+    fn associated_body(self) -> Option<BodyId> {
         match self {
             EntryItem(_, item) => {
                 match item.node {
                     ItemConst(_, body) |
                     ItemStatic(.., body) |
-                    ItemFn(_, _, _, _, _, body) => body.node_id == node_id,
-                    _ => false
+                    ItemFn(_, _, _, _, _, body) => Some(body),
+                    _ => None,
                 }
             }
 
             EntryTraitItem(_, item) => {
                 match item.node {
                     TraitItemKind::Const(_, Some(body)) |
-                    TraitItemKind::Method(_, TraitMethod::Provided(body)) => {
-                        body.node_id == node_id
-                    }
-                    _ => false
+                    TraitItemKind::Method(_, TraitMethod::Provided(body)) => Some(body),
+                    _ => None
                 }
             }
 
             EntryImplItem(_, item) => {
                 match item.node {
                     ImplItemKind::Const(_, body) |
-                    ImplItemKind::Method(_, body) => body.node_id == node_id,
-                    _ => false
+                    ImplItemKind::Method(_, body) => Some(body),
+                    _ => None,
                 }
             }
 
             EntryExpr(_, expr) => {
                 match expr.node {
-                    ExprClosure(.., body, _) => body.node_id == node_id,
-                    _ => false
+                    ExprClosure(.., body, _) => Some(body),
+                    _ => None,
                 }
             }
 
-            _ => false
+            _ => None
+        }
+    }
+
+    fn is_body_owner(self, node_id: NodeId) -> bool {
+        match self.associated_body() {
+            Some(b) => b.node_id == node_id,
+            None => false,
         }
     }
 }

src/librustc/hir/mod.rs

@@ -31,7 +31,7 @@ pub use self::PathParameters::*;
 
 use hir::def::Def;
 use hir::def_id::DefId;
-use util::nodemap::{NodeMap, FxHashMap, FxHashSet};
+use util::nodemap::{NodeMap, FxHashSet};
 
 use syntax_pos::{Span, ExpnId, DUMMY_SP};
 use syntax::codemap::{self, Spanned};
@@ -409,7 +409,13 @@ pub struct Crate {
 
     pub trait_items: BTreeMap<TraitItemId, TraitItem>,
     pub impl_items: BTreeMap<ImplItemId, ImplItem>,
-    pub bodies: FxHashMap<BodyId, Body>,
+    pub bodies: BTreeMap<BodyId, Body>,
+
+    /// A list of the body ids written out in the order in which they
+    /// appear in the crate. If you're going to process all the bodies
+    /// in the crate, you should iterate over this list rather than the keys
+    /// of bodies.
+    pub body_ids: Vec<BodyId>,
 }
 
 impl Crate {

src/librustc/middle/free_region.rs

@@ -19,7 +19,7 @@ use ty::{self, TyCtxt, FreeRegion, Region};
 use ty::wf::ImpliedBound;
 use rustc_data_structures::transitive_relation::TransitiveRelation;
 
-#[derive(Clone)]
+#[derive(Clone, RustcEncodable, RustcDecodable)]
 pub struct FreeRegionMap {
     // Stores the relation `a < b`, where `a` and `b` are regions.
     relation: TransitiveRelation<Region>
@@ -30,6 +30,10 @@ impl FreeRegionMap {
         FreeRegionMap { relation: TransitiveRelation::new() }
     }
 
+    pub fn is_empty(&self) -> bool {
+        self.relation.is_empty()
+    }
+
     pub fn relate_free_regions_from_implied_bounds<'tcx>(&mut self,
                                                         implied_bounds: &[ImpliedBound<'tcx>])
     {

src/librustc/ty/context.rs

@@ -242,6 +242,11 @@ pub struct TypeckTables<'tcx> {
 
     /// Lints for the body of this fn generated by typeck.
     pub lints: lint::LintTable,
+
+    /// Stores the free-region relationships that were deduced from
+    /// its where clauses and parameter types. These are then
+    /// read-again by borrowck.
+    pub free_region_map: FreeRegionMap,
 }
 
 impl<'tcx> TypeckTables<'tcx> {
@@ -259,6 +264,7 @@ impl<'tcx> TypeckTables<'tcx> {
             fru_field_types: NodeMap(),
             cast_kinds: NodeMap(),
             lints: lint::LintTable::new(),
+            free_region_map: FreeRegionMap::new(),
         }
     }
 
@@ -406,14 +412,6 @@ pub struct GlobalCtxt<'tcx> {
 
     pub region_maps: RegionMaps,
 
-    // For each fn declared in the local crate, type check stores the
-    // free-region relationships that were deduced from its where
-    // clauses and parameter types. These are then read-again by
-    // borrowck. (They are not used during trans, and hence are not
-    // serialized or needed for cross-crate fns.)
-    free_region_maps: RefCell<NodeMap<FreeRegionMap>>,
-    // FIXME: jroesch make this a refcell
-
     pub tables: RefCell<DepTrackingMap<maps::TypeckTables<'tcx>>>,
 
     /// Maps from a trait item to the trait item "descriptor"
@@ -706,16 +704,6 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         interned
     }
 
-    pub fn store_free_region_map(self, id: NodeId, map: FreeRegionMap) {
-        if self.free_region_maps.borrow_mut().insert(id, map).is_some() {
-            bug!("Tried to overwrite interned FreeRegionMap for NodeId {:?}", id)
-        }
-    }
-
-    pub fn free_region_map(self, id: NodeId) -> FreeRegionMap {
-        self.free_region_maps.borrow()[&id].clone()
-    }
-
     pub fn lift<T: ?Sized + Lift<'tcx>>(self, value: &T) -> Option<T::Lifted> {
         value.lift_to_tcx(self)
     }
@@ -762,7 +750,6 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
             types: common_types,
             named_region_map: named_region_map,
             region_maps: region_maps,
-            free_region_maps: RefCell::new(FxHashMap()),
             item_variance_map: RefCell::new(DepTrackingMap::new(dep_graph.clone())),
             variance_computed: Cell::new(false),
             sess: s,

src/librustc/ty/mod.rs

@@ -2668,6 +2668,17 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         dep_graph::visit_all_item_likes_in_krate(self.global_tcx(), dep_node_fn, visitor);
     }
 
+    /// Invokes `callback` for each body in the krate. This will
+    /// create a read edge from `DepNode::Krate` to the current task;
+    /// it is meant to be run in the context of some global task like
+    /// `BorrowckCrate`. The callback would then create a task like
+    /// `BorrowckBody(DefId)` to process each individual item.
+    pub fn visit_all_bodies_in_krate<C>(self, callback: C)
+        where C: Fn(/* body_owner */ DefId, /* body id */ hir::BodyId),
+    {
+        dep_graph::visit_all_bodies_in_krate(self.global_tcx(), callback)
+    }
+
     /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
     /// with the name of the crate containing the impl.
     pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {

src/librustc_borrowck/borrowck/fragments.rs

@@ -27,7 +27,7 @@ use rustc::middle::mem_categorization as mc;
 use std::mem;
 use std::rc::Rc;
 use syntax::ast;
-use syntax_pos::{Span, DUMMY_SP};
+use syntax_pos::DUMMY_SP;
 
 #[derive(PartialEq, Eq, PartialOrd, Ord)]
 enum Fragment {
@@ -200,14 +200,15 @@ impl FragmentSets {
 
 pub fn instrument_move_fragments<'a, 'tcx>(this: &MoveData<'tcx>,
                                            tcx: TyCtxt<'a, 'tcx, 'tcx>,
-                                           sp: Span,
                                            id: ast::NodeId) {
     let span_err = tcx.hir.attrs(id).iter()
                           .any(|a| a.check_name("rustc_move_fragments"));
     let print = tcx.sess.opts.debugging_opts.print_move_fragments;
 
     if !span_err && !print { return; }
 
+    let sp = tcx.hir.span(id);
+
     let instrument_all_paths = |kind, vec_rc: &Vec<MovePathIndex>| {
         for (i, mpi) in vec_rc.iter().enumerate() {
             let lp = || this.path_loan_path(*mpi);