1 // Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 // Finds items that are externally reachable, to determine which items
12 // need to have their metadata (and possibly their AST) serialized.
13 // All items that can be referred to through an exported name are
14 // reachable, and when a reachable thing is inline or generic, it
15 // makes all other generics or inline functions that it references
18 use hir::map as hir_map;
20 use hir::def_id::{DefId, CrateNum};
22 use ty::{self, TyCtxt};
23 use ty::maps::Providers;
26 use util::nodemap::{NodeSet, FxHashSet};
31 use syntax::codemap::DUMMY_SP;
33 use hir::def_id::LOCAL_CRATE;
34 use hir::intravisit::{Visitor, NestedVisitorMap};
35 use hir::itemlikevisit::ItemLikeVisitor;
38 // Returns true if the given set of generics implies that the item it's
39 // associated with must be inlined.
40 fn generics_require_inlining(generics: &hir::Generics) -> bool {
41 !generics.ty_params.is_empty()
44 // Returns true if the given item must be inlined because it may be
45 // monomorphized or it was marked with `#[inline]`. This will only return
46 // true for functions.
47 fn item_might_be_inlined(item: &hir::Item) -> bool {
48 if attr::requests_inline(&item.attrs) {
53 hir::ItemImpl(_, _, ref generics, ..) |
54 hir::ItemFn(.., ref generics, _) => {
55 generics_require_inlining(generics)
61 fn method_might_be_inlined<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
63 impl_item: &hir::ImplItem,
64 impl_src: DefId) -> bool {
65 if attr::requests_inline(&impl_item.attrs) ||
66 generics_require_inlining(&sig.generics) {
69 if let Some(impl_node_id) = tcx.hir.as_local_node_id(impl_src) {
70 match tcx.hir.find(impl_node_id) {
71 Some(hir_map::NodeItem(item)) =>
72 item_might_be_inlined(&item),
74 span_bug!(impl_item.span, "impl did is not an item")
77 span_bug!(impl_item.span, "found a foreign impl as a parent of a local method")
81 // Information needed while computing reachability.
82 struct ReachableContext<'a, 'tcx: 'a> {
84 tcx: TyCtxt<'a, 'tcx, 'tcx>,
85 tables: &'a ty::TypeckTables<'tcx>,
86 // The set of items which must be exported in the linkage sense.
87 reachable_symbols: NodeSet,
88 // A worklist of item IDs. Each item ID in this worklist will be inlined
89 // and will be scanned for further references.
90 worklist: Vec<ast::NodeId>,
91 // Whether any output of this compilation is a library
95 impl<'a, 'tcx> Visitor<'tcx> for ReachableContext<'a, 'tcx> {
96 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
97 NestedVisitorMap::None
100 fn visit_nested_body(&mut self, body: hir::BodyId) {
101 let old_tables = self.tables;
102 self.tables = self.tcx.body_tables(body);
103 let body = self.tcx.hir.body(body);
104 self.visit_body(body);
105 self.tables = old_tables;
108 fn visit_expr(&mut self, expr: &'tcx hir::Expr) {
109 let def = match expr.node {
110 hir::ExprPath(ref qpath) => {
111 Some(self.tables.qpath_def(qpath, expr.id))
113 hir::ExprMethodCall(..) => {
114 let method_call = ty::MethodCall::expr(expr.id);
115 let def_id = self.tables.method_map[&method_call].def_id;
116 Some(Def::Method(def_id))
121 if let Some(def) = def {
122 let def_id = def.def_id();
123 if let Some(node_id) = self.tcx.hir.as_local_node_id(def_id) {
124 if self.def_id_represents_local_inlined_item(def_id) {
125 self.worklist.push(node_id);
128 // If this path leads to a constant, then we need to
129 // recurse into the constant to continue finding
130 // items that are reachable.
131 Def::Const(..) | Def::AssociatedConst(..) => {
132 self.worklist.push(node_id);
135 // If this wasn't a static, then the destination is
138 self.reachable_symbols.insert(node_id);
145 intravisit::walk_expr(self, expr)
149 impl<'a, 'tcx> ReachableContext<'a, 'tcx> {
150 // Returns true if the given def ID represents a local item that is
151 // eligible for inlining and false otherwise.
152 fn def_id_represents_local_inlined_item(&self, def_id: DefId) -> bool {
153 let node_id = match self.tcx.hir.as_local_node_id(def_id) {
154 Some(node_id) => node_id,
155 None => { return false; }
158 match self.tcx.hir.find(node_id) {
159 Some(hir_map::NodeItem(item)) => {
161 hir::ItemFn(..) => item_might_be_inlined(&item),
165 Some(hir_map::NodeTraitItem(trait_method)) => {
166 match trait_method.node {
167 hir::TraitItemKind::Const(_, ref default) => default.is_some(),
168 hir::TraitItemKind::Method(_, hir::TraitMethod::Provided(_)) => true,
169 hir::TraitItemKind::Method(_, hir::TraitMethod::Required(_)) |
170 hir::TraitItemKind::Type(..) => false,
173 Some(hir_map::NodeImplItem(impl_item)) => {
174 match impl_item.node {
175 hir::ImplItemKind::Const(..) => true,
176 hir::ImplItemKind::Method(ref sig, _) => {
177 if generics_require_inlining(&sig.generics) ||
178 attr::requests_inline(&impl_item.attrs) {
181 let impl_did = self.tcx
183 .get_parent_did(node_id);
184 // Check the impl. If the generics on the self
185 // type of the impl require inlining, this method
187 let impl_node_id = self.tcx.hir.as_local_node_id(impl_did).unwrap();
188 match self.tcx.hir.expect_item(impl_node_id).node {
189 hir::ItemImpl(_, _, ref generics, ..) => {
190 generics_require_inlining(generics)
196 hir::ImplItemKind::Type(_) => false,
200 None => false // This will happen for default methods.
204 // Step 2: Mark all symbols that the symbols on the worklist touch.
205 fn propagate(&mut self) {
206 let mut scanned = FxHashSet();
208 let search_item = match self.worklist.pop() {
212 if !scanned.insert(search_item) {
216 if let Some(ref item) = self.tcx.hir.find(search_item) {
217 self.propagate_node(item, search_item);
222 fn propagate_node(&mut self, node: &hir_map::Node<'tcx>,
223 search_item: ast::NodeId) {
224 if !self.any_library {
225 // If we are building an executable, only explicitly extern
226 // types need to be exported.
227 if let hir_map::NodeItem(item) = *node {
228 let reachable = if let hir::ItemFn(.., abi, _, _) = item.node {
233 let is_extern = attr::contains_extern_indicator(&self.tcx.sess.diagnostic(),
235 if reachable || is_extern {
236 self.reachable_symbols.insert(search_item);
240 // If we are building a library, then reachable symbols will
241 // continue to participate in linkage after this product is
242 // produced. In this case, we traverse the ast node, recursing on
243 // all reachable nodes from this one.
244 self.reachable_symbols.insert(search_item);
248 hir_map::NodeItem(item) => {
250 hir::ItemFn(.., body) => {
251 if item_might_be_inlined(&item) {
252 self.visit_nested_body(body);
256 // Reachable constants will be inlined into other crates
257 // unconditionally, so we need to make sure that their
258 // contents are also reachable.
259 hir::ItemConst(_, init) => {
260 self.visit_nested_body(init);
263 // These are normal, nothing reachable about these
264 // inherently and their children are already in the
265 // worklist, as determined by the privacy pass
266 hir::ItemExternCrate(_) | hir::ItemUse(..) |
267 hir::ItemTy(..) | hir::ItemStatic(..) |
268 hir::ItemMod(..) | hir::ItemForeignMod(..) |
269 hir::ItemImpl(..) | hir::ItemTrait(..) |
270 hir::ItemStruct(..) | hir::ItemEnum(..) |
271 hir::ItemUnion(..) | hir::ItemDefaultImpl(..) |
272 hir::ItemGlobalAsm(..) => {}
275 hir_map::NodeTraitItem(trait_method) => {
276 match trait_method.node {
277 hir::TraitItemKind::Const(_, None) |
278 hir::TraitItemKind::Method(_, hir::TraitMethod::Required(_)) => {
279 // Keep going, nothing to get exported
281 hir::TraitItemKind::Const(_, Some(body_id)) |
282 hir::TraitItemKind::Method(_, hir::TraitMethod::Provided(body_id)) => {
283 self.visit_nested_body(body_id);
285 hir::TraitItemKind::Type(..) => {}
288 hir_map::NodeImplItem(impl_item) => {
289 match impl_item.node {
290 hir::ImplItemKind::Const(_, body) => {
291 self.visit_nested_body(body);
293 hir::ImplItemKind::Method(ref sig, body) => {
294 let did = self.tcx.hir.get_parent_did(search_item);
295 if method_might_be_inlined(self.tcx, sig, impl_item, did) {
296 self.visit_nested_body(body)
299 hir::ImplItemKind::Type(_) => {}
302 // Nothing to recurse on for these
303 hir_map::NodeForeignItem(_) |
304 hir_map::NodeVariant(_) |
305 hir_map::NodeStructCtor(_) |
306 hir_map::NodeField(_) |
307 hir_map::NodeTy(_) => {}
309 bug!("found unexpected thingy in worklist: {}",
310 self.tcx.hir.node_to_string(search_item))
316 // Some methods from non-exported (completely private) trait impls still have to be
317 // reachable if they are called from inlinable code. Generally, it's not known until
318 // monomorphization if a specific trait impl item can be reachable or not. So, we
319 // conservatively mark all of them as reachable.
320 // FIXME: One possible strategy for pruning the reachable set is to avoid marking impl
321 // items of non-exported traits (or maybe all local traits?) unless their respective
322 // trait items are used from inlinable code through method call syntax or UFCS, or their
323 // trait is a lang item.
324 struct CollectPrivateImplItemsVisitor<'a, 'tcx: 'a> {
325 tcx: TyCtxt<'a, 'tcx, 'tcx>,
326 access_levels: &'a privacy::AccessLevels,
327 worklist: &'a mut Vec<ast::NodeId>,
330 impl<'a, 'tcx: 'a> ItemLikeVisitor<'tcx> for CollectPrivateImplItemsVisitor<'a, 'tcx> {
331 fn visit_item(&mut self, item: &hir::Item) {
332 // We need only trait impls here, not inherent impls, and only non-exported ones
333 if let hir::ItemImpl(.., Some(ref trait_ref), _, ref impl_item_refs) = item.node {
334 if !self.access_levels.is_reachable(item.id) {
335 for impl_item_ref in impl_item_refs {
336 self.worklist.push(impl_item_ref.id.node_id);
339 let trait_def_id = match trait_ref.path.def {
340 Def::Trait(def_id) => def_id,
344 if !trait_def_id.is_local() {
348 for default_method in self.tcx.provided_trait_methods(trait_def_id) {
349 let node_id = self.tcx
351 .as_local_node_id(default_method.def_id)
353 self.worklist.push(node_id);
359 fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem) {}
361 fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem) {
362 // processed in visit_item above
366 pub fn find_reachable<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Rc<NodeSet> {
367 ty::queries::reachable_set::get(tcx, DUMMY_SP, LOCAL_CRATE)
370 fn reachable_set<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, crate_num: CrateNum) -> Rc<NodeSet> {
371 debug_assert!(crate_num == LOCAL_CRATE);
373 let access_levels = &ty::queries::privacy_access_levels::get(tcx, DUMMY_SP, LOCAL_CRATE);
375 let any_library = tcx.sess.crate_types.borrow().iter().any(|ty| {
376 *ty == config::CrateTypeRlib || *ty == config::CrateTypeDylib ||
377 *ty == config::CrateTypeProcMacro
379 let mut reachable_context = ReachableContext {
381 tables: &ty::TypeckTables::empty(),
382 reachable_symbols: NodeSet(),
383 worklist: Vec::new(),
384 any_library: any_library,
387 // Step 1: Seed the worklist with all nodes which were found to be public as
388 // a result of the privacy pass along with all local lang items and impl items.
389 // If other crates link to us, they're going to expect to be able to
390 // use the lang items, so we need to be sure to mark them as
392 for (id, _) in &access_levels.map {
393 reachable_context.worklist.push(*id);
395 for item in tcx.lang_items.items().iter() {
396 if let Some(did) = *item {
397 if let Some(node_id) = tcx.hir.as_local_node_id(did) {
398 reachable_context.worklist.push(node_id);
403 let mut collect_private_impl_items = CollectPrivateImplItemsVisitor {
405 access_levels: access_levels,
406 worklist: &mut reachable_context.worklist,
408 tcx.hir.krate().visit_all_item_likes(&mut collect_private_impl_items);
411 // Step 2: Mark all symbols that the symbols on the worklist touch.
412 reachable_context.propagate();
414 // Return the set of reachable symbols.
415 Rc::new(reachable_context.reachable_symbols)
418 pub fn provide(providers: &mut Providers) {
419 *providers = Providers {