Rollup merge of #35114 - michaelwoerister:inline-meta-to-hir-map, r=eddyb

Move caching of inlined HIR into CrateStore

So far we've had separate HIR-inlining caches for each codegen unit and the caching for things inlined during constant evaluation had some holes. Consequently, things would be inlined multiple times if they were used from different codegen units, etc, leading to
- wasted memory,
- multiple `NodeId`s per `DefId` and,
- for things inlined during constant evaluation, no way to map a `NodeId` back to it's original `DefId`.

This PR moves all caching into the CrateStore, solving all of the above problems. It also fixes some bugs in the inlining code, like cyclic in the parent-chains in the HIR map and some `NodeId`'s being translated to more or less random values. There are assertions in place now that should prevent this kind of thing in the future.

This PR based on top of #35090, which contains some necessary fixes.

Author: sanxiyn

src/librustc/hir/intravisit.rs

@@ -867,7 +867,7 @@ pub fn walk_vis<'v, V: Visitor<'v>>(visitor: &mut V, vis: &'v Visibility) {
     }
 }
 
-#[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug)]
+#[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug, PartialEq, Eq)]
 pub struct IdRange {
     pub min: NodeId,
     pub max: NodeId,
@@ -893,6 +893,7 @@ impl IdRange {
         self.min = cmp::min(self.min, id);
         self.max = cmp::max(self.max, id + 1);
     }
+
 }
 
 

src/librustc/hir/map/mod.rs

@@ -32,6 +32,7 @@ use hir::print as pprust;
 
 use arena::TypedArena;
 use std::cell::RefCell;
+use std::cmp;
 use std::io;
 use std::mem;
 
@@ -127,7 +128,10 @@ impl<'ast> MapEntry<'ast> {
             EntryStructCtor(id, _) => id,
             EntryLifetime(id, _) => id,
             EntryTyParam(id, _) => id,
-            _ => return None
+
+            NotPresent |
+            RootCrate |
+            RootInlinedParent(_) => return None,
         })
     }
 
@@ -196,6 +200,10 @@ pub struct Map<'ast> {
     map: RefCell<Vec<MapEntry<'ast>>>,
 
     definitions: RefCell<Definitions>,
+
+    /// All NodeIds that are numerically greater or equal to this value come
+    /// from inlined items.
+    local_node_id_watermark: NodeId,
 }
 
 impl<'ast> Map<'ast> {
@@ -550,6 +558,13 @@ impl<'ast> Map<'ast> {
         }
     }
 
+    pub fn expect_inlined_item(&self, id: NodeId) -> &'ast InlinedItem {
+        match self.find_entry(id) {
+            Some(RootInlinedParent(inlined_item)) => inlined_item,
+            _ => bug!("expected inlined item, found {}", self.node_to_string(id)),
+        }
+    }
+
     /// Returns the name associated with the given NodeId's AST.
     pub fn name(&self, id: NodeId) -> Name {
         match self.get(id) {
@@ -649,6 +664,10 @@ impl<'ast> Map<'ast> {
     pub fn node_to_user_string(&self, id: NodeId) -> String {
         node_id_to_string(self, id, false)
     }
+
+    pub fn is_inlined(&self, id: NodeId) -> bool {
+        id >= self.local_node_id_watermark
+    }
 }
 
 pub struct NodesMatchingSuffix<'a, 'ast:'a> {
@@ -765,13 +784,37 @@ pub trait FoldOps {
 }
 
 /// A Folder that updates IDs and Span's according to fold_ops.
-struct IdAndSpanUpdater<F> {
-    fold_ops: F
+pub struct IdAndSpanUpdater<F> {
+    fold_ops: F,
+    min_id_assigned: NodeId,
+    max_id_assigned: NodeId,
+}
+
+impl<F: FoldOps> IdAndSpanUpdater<F> {
+    pub fn new(fold_ops: F) -> IdAndSpanUpdater<F> {
+        IdAndSpanUpdater {
+            fold_ops: fold_ops,
+            min_id_assigned: ::std::u32::MAX,
+            max_id_assigned: ::std::u32::MIN,
+        }
+    }
+
+    pub fn id_range(&self) -> intravisit::IdRange {
+        intravisit::IdRange {
+            min: self.min_id_assigned,
+            max: self.max_id_assigned + 1,
+        }
+    }
 }
 
 impl<F: FoldOps> Folder for IdAndSpanUpdater<F> {
     fn new_id(&mut self, id: NodeId) -> NodeId {
-        self.fold_ops.new_id(id)
+        let id = self.fold_ops.new_id(id);
+
+        self.min_id_assigned = cmp::min(self.min_id_assigned, id);
+        self.max_id_assigned = cmp::max(self.max_id_assigned, id);
+
+        id
     }
 
     fn new_span(&mut self, span: Span) -> Span {
@@ -802,11 +845,14 @@ pub fn map_crate<'ast>(forest: &'ast mut Forest,
               entries, vector_length, (entries as f64 / vector_length as f64) * 100.);
     }
 
+    let local_node_id_watermark = map.len() as NodeId;
+
     Map {
         forest: forest,
         dep_graph: forest.dep_graph.clone(),
         map: RefCell::new(map),
         definitions: RefCell::new(definitions),
+        local_node_id_watermark: local_node_id_watermark
     }
 }
 
@@ -818,7 +864,7 @@ pub fn map_decoded_item<'ast, F: FoldOps>(map: &Map<'ast>,
                                           ii: InlinedItem,
                                           fold_ops: F)
                                           -> &'ast InlinedItem {
-    let mut fld = IdAndSpanUpdater { fold_ops: fold_ops };
+    let mut fld = IdAndSpanUpdater::new(fold_ops);
     let ii = match ii {
         II::Item(i) => II::Item(i.map(|i| fld.fold_item(i))),
         II::TraitItem(d, ti) => {
@@ -835,6 +881,12 @@ pub fn map_decoded_item<'ast, F: FoldOps>(map: &Map<'ast>,
     let ii = map.forest.inlined_items.alloc(ii);
     let ii_parent_id = fld.new_id(DUMMY_NODE_ID);
 
+    // Assert that the ii_parent_id is the last NodeId in our reserved range
+    assert!(ii_parent_id == fld.max_id_assigned);
+    // Assert that we did not violate the invariant that all inlined HIR items
+    // have NodeIds greater than or equal to `local_node_id_watermark`
+    assert!(fld.min_id_assigned >= map.local_node_id_watermark);
+
     let defs = &mut *map.definitions.borrow_mut();
     let mut def_collector = DefCollector::extend(ii_parent_id,
                                                  parent_def_path.clone(),

src/librustc/middle/cstore.rs

@@ -120,12 +120,6 @@ pub struct ChildItem {
     pub vis: ty::Visibility,
 }
 
-pub enum FoundAst<'ast> {
-    Found(&'ast InlinedItem),
-    FoundParent(DefId, &'ast hir::Item),
-    NotFound,
-}
-
 #[derive(Copy, Clone, Debug)]
 pub struct ExternCrate {
     /// def_id of an `extern crate` in the current crate that caused
@@ -250,7 +244,10 @@ pub trait CrateStore<'tcx> {
 
     // misc. metadata
     fn maybe_get_item_ast<'a>(&'tcx self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId)
-                              -> FoundAst<'tcx>;
+                              -> Option<(&'tcx InlinedItem, ast::NodeId)>;
+    fn local_node_for_inlined_defid(&'tcx self, def_id: DefId) -> Option<ast::NodeId>;
+    fn defid_for_inlined_node(&'tcx self, node_id: ast::NodeId) -> Option<DefId>;
+
     fn maybe_get_item_mir<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId)
                               -> Option<Mir<'tcx>>;
     fn is_item_mir_available(&self, def: DefId) -> bool;
@@ -447,7 +444,16 @@ impl<'tcx> CrateStore<'tcx> for DummyCrateStore {
 
     // misc. metadata
     fn maybe_get_item_ast<'a>(&'tcx self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId)
-                              -> FoundAst<'tcx> { bug!("maybe_get_item_ast") }
+                              -> Option<(&'tcx InlinedItem, ast::NodeId)> {
+        bug!("maybe_get_item_ast")
+    }
+    fn local_node_for_inlined_defid(&'tcx self, def_id: DefId) -> Option<ast::NodeId> {
+        bug!("local_node_for_inlined_defid")
+    }
+    fn defid_for_inlined_node(&'tcx self, node_id: ast::NodeId) -> Option<DefId> {
+        bug!("defid_for_inlined_node")
+    }
+
     fn maybe_get_item_mir<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId)
                               -> Option<Mir<'tcx>> { bug!("maybe_get_item_mir") }
     fn is_item_mir_available(&self, def: DefId) -> bool {

src/librustc_const_eval/eval.rs

@@ -17,7 +17,7 @@ use self::EvalHint::*;
 
 use rustc::hir::map as ast_map;
 use rustc::hir::map::blocks::FnLikeNode;
-use rustc::middle::cstore::{self, InlinedItem};
+use rustc::middle::cstore::InlinedItem;
 use rustc::traits;
 use rustc::hir::def::{Def, PathResolution};
 use rustc::hir::def_id::DefId;
@@ -142,13 +142,13 @@ pub fn lookup_const_by_id<'a, 'tcx: 'a>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
         }
         let mut used_substs = false;
         let expr_ty = match tcx.sess.cstore.maybe_get_item_ast(tcx, def_id) {
-            cstore::FoundAst::Found(&InlinedItem::Item(ref item)) => match item.node {
+            Some((&InlinedItem::Item(ref item), _)) => match item.node {
                 hir::ItemConst(ref ty, ref const_expr) => {
                     Some((&**const_expr, tcx.ast_ty_to_prim_ty(ty)))
                 },
                 _ => None
             },
-            cstore::FoundAst::Found(&InlinedItem::TraitItem(trait_id, ref ti)) => match ti.node {
+            Some((&InlinedItem::TraitItem(trait_id, ref ti), _)) => match ti.node {
                 hir::ConstTraitItem(_, _) => {
                     used_substs = true;
                     if let Some(substs) = substs {
@@ -163,7 +163,7 @@ pub fn lookup_const_by_id<'a, 'tcx: 'a>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                 }
                 _ => None
             },
-            cstore::FoundAst::Found(&InlinedItem::ImplItem(_, ref ii)) => match ii.node {
+            Some((&InlinedItem::ImplItem(_, ref ii), _)) => match ii.node {
                 hir::ImplItemKind::Const(ref ty, ref expr) => {
                     Some((&**expr, tcx.ast_ty_to_prim_ty(ty)))
                 },
@@ -198,8 +198,8 @@ fn inline_const_fn_from_external_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     }
 
     let fn_id = match tcx.sess.cstore.maybe_get_item_ast(tcx, def_id) {
-        cstore::FoundAst::Found(&InlinedItem::Item(ref item)) => Some(item.id),
-        cstore::FoundAst::Found(&InlinedItem::ImplItem(_, ref item)) => Some(item.id),
+        Some((&InlinedItem::Item(ref item), _)) => Some(item.id),
+        Some((&InlinedItem::ImplItem(_, ref item), _)) => Some(item.id),
         _ => None
     };
     tcx.extern_const_fns.borrow_mut().insert(def_id,

src/librustc_metadata/astencode.rs

@@ -88,8 +88,9 @@ pub fn encode_inlined_item(ecx: &e::EncodeContext,
            rbml_w.writer.seek(SeekFrom::Current(0)));
 
     // Folding could be avoided with a smarter encoder.
-    let ii = simplify_ast(ii);
+    let (ii, expected_id_range) = simplify_ast(ii);
     let id_range = inlined_item_id_range(&ii);
+    assert_eq!(expected_id_range, id_range);
 
     rbml_w.start_tag(c::tag_ast as usize);
     id_range.encode(rbml_w);
@@ -186,6 +187,10 @@ impl<'a, 'b, 'tcx> DecodeContext<'a, 'b, 'tcx> {
     pub fn tr_id(&self, id: ast::NodeId) -> ast::NodeId {
         // from_id_range should be non-empty
         assert!(!self.from_id_range.empty());
+        // Make sure that translating the NodeId will actually yield a
+        // meaningful result
+        assert!(self.from_id_range.contains(id));
+
         // Use wrapping arithmetic because otherwise it introduces control flow.
         // Maybe we should just have the control flow? -- aatch
         (id.wrapping_sub(self.from_id_range.min).wrapping_add(self.to_id_range.min))
@@ -279,9 +284,23 @@ fn encode_ast(rbml_w: &mut Encoder, item: &InlinedItem) {
     rbml_w.end_tag();
 }
 
-struct NestedItemsDropper;
+struct NestedItemsDropper {
+    id_range: IdRange
+}
 
 impl Folder for NestedItemsDropper {
+
+    // The unit tests below run on HIR with NodeIds not properly assigned. That
+    // causes an integer overflow. So we just don't track the id_range when
+    // building the unit tests.
+    #[cfg(not(test))]
+    fn new_id(&mut self, id: ast::NodeId) -> ast::NodeId {
+        // Record the range of NodeIds we are visiting, so we can do a sanity
+        // check later
+        self.id_range.add(id);
+        id
+    }
+
     fn fold_block(&mut self, blk: P<hir::Block>) -> P<hir::Block> {
         blk.and_then(|hir::Block {id, stmts, expr, rules, span, ..}| {
             let stmts_sans_items = stmts.into_iter().filter_map(|stmt| {
@@ -322,10 +341,12 @@ impl Folder for NestedItemsDropper {
 // As it happens, trans relies on the fact that we do not export
 // nested items, as otherwise it would get confused when translating
 // inlined items.
-fn simplify_ast(ii: InlinedItemRef) -> InlinedItem {
-    let mut fld = NestedItemsDropper;
+fn simplify_ast(ii: InlinedItemRef) -> (InlinedItem, IdRange) {
+    let mut fld = NestedItemsDropper {
+        id_range: IdRange::max()
+    };
 
-    match ii {
+    let ii = match ii {
         // HACK we're not dropping items.
         InlinedItemRef::Item(i) => {
             InlinedItem::Item(P(fold::noop_fold_item(i.clone(), &mut fld)))
@@ -339,7 +360,9 @@ fn simplify_ast(ii: InlinedItemRef) -> InlinedItem {
         InlinedItemRef::Foreign(i) => {
             InlinedItem::Foreign(P(fold::noop_fold_foreign_item(i.clone(), &mut fld)))
         }
-    }
+    };
+
+    (ii, fld.id_range)
 }
 
 fn decode_ast(item_doc: rbml::Doc) -> InlinedItem {
@@ -361,8 +384,18 @@ impl tr for Def {
         match *self {
           Def::Fn(did) => Def::Fn(did.tr(dcx)),
           Def::Method(did) => Def::Method(did.tr(dcx)),
-          Def::SelfTy(opt_did, impl_id) => { Def::SelfTy(opt_did.map(|did| did.tr(dcx)),
-                                                         impl_id.map(|id| dcx.tr_id(id))) }
+          Def::SelfTy(opt_did, impl_id) => {
+              // Since the impl_id will never lie within the reserved range of
+              // imported NodeIds, it does not make sense to translate it.
+              // The result would not make any sense within the importing crate.
+              // We also don't allow for impl items to be inlined (just their
+              // members), so even if we had a DefId here, we wouldn't be able
+              // to do much with it.
+              // So, we set the id to DUMMY_NODE_ID. That way we make it
+              // explicit that this is no usable NodeId.
+              Def::SelfTy(opt_did.map(|did| did.tr(dcx)),
+                          impl_id.map(|_| ast::DUMMY_NODE_ID))
+          }
           Def::Mod(did) => { Def::Mod(did.tr(dcx)) }
           Def::ForeignMod(did) => { Def::ForeignMod(did.tr(dcx)) }
           Def::Static(did, m) => { Def::Static(did.tr(dcx), m) }
@@ -1361,7 +1394,7 @@ fn test_simplification() {
     with_testing_context(|lcx| {
         let hir_item = lcx.lower_item(&item);
         let item_in = InlinedItemRef::Item(&hir_item);
-        let item_out = simplify_ast(item_in);
+        let (item_out, _) = simplify_ast(item_in);
         let item_exp = InlinedItem::Item(P(lcx.lower_item(&quote_item!(&cx,
             fn new_int_alist<B>() -> alist<isize, B> {
                 return alist {eq_fn: eq_int, data: Vec::new()};