1 // Copyright 2012-2014 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 //! Calculation of the (misnamed) "strict version hash" for crates and
12 //! items. This hash is used to tell when the HIR changed in such a
13 //! way that results from previous compilations may no longer be
14 //! applicable and hence must be recomputed. It should probably be
15 //! renamed to the ICH (incremental compilation hash).
17 //! The hashes for all items are computed once at the beginning of
18 //! compilation and stored into a map. In addition, a hash is computed
19 //! of the **entire crate**.
21 //! Storing the hashes in a map avoids the need to compute them twice
22 //! (once when loading prior incremental results and once when
23 //! saving), but it is also important for correctness: at least as of
24 //! the time of this writing, the typeck passes rewrites entries in
25 //! the dep-map in-place to accommodate UFCS resolutions. Since name
26 //! resolution is part of the hash, the result is that hashes computed
27 //! at the end of compilation would be different from those computed
31 use std::cell::RefCell;
33 use rustc::dep_graph::DepNode;
35 use rustc::hir::def_id::{CRATE_DEF_INDEX, DefId};
36 use rustc::hir::intravisit as visit;
37 use rustc::hir::intravisit::{Visitor, NestedVisitorMap};
38 use rustc::ich::{Fingerprint, DefPathHashes, CachingCodemapView};
39 use rustc::ty::TyCtxt;
40 use rustc_data_structures::stable_hasher::StableHasher;
41 use rustc_data_structures::fx::FxHashMap;
42 use rustc::util::common::record_time;
43 use rustc::session::config::DebugInfoLevel::NoDebugInfo;
45 use self::svh_visitor::StrictVersionHashVisitor;
49 pub type IchHasher = StableHasher<Fingerprint>;
51 pub struct IncrementalHashesMap {
52 hashes: FxHashMap<DepNode<DefId>, Fingerprint>,
54 // These are the metadata hashes for the current crate as they were stored
55 // during the last compilation session. They are only loaded if
56 // -Z query-dep-graph was specified and are needed for auto-tests using
57 // the #[rustc_metadata_dirty] and #[rustc_metadata_clean] attributes to
58 // check whether some metadata hash has changed in between two revisions.
59 pub prev_metadata_hashes: RefCell<FxHashMap<DefId, Fingerprint>>,
62 impl IncrementalHashesMap {
63 pub fn new() -> IncrementalHashesMap {
64 IncrementalHashesMap {
66 prev_metadata_hashes: RefCell::new(FxHashMap()),
70 pub fn insert(&mut self, k: DepNode<DefId>, v: Fingerprint) -> Option<Fingerprint> {
71 self.hashes.insert(k, v)
74 pub fn iter<'a>(&'a self)
75 -> ::std::collections::hash_map::Iter<'a, DepNode<DefId>, Fingerprint> {
79 pub fn len(&self) -> usize {
84 impl<'a> ::std::ops::Index<&'a DepNode<DefId>> for IncrementalHashesMap {
85 type Output = Fingerprint;
87 fn index(&self, index: &'a DepNode<DefId>) -> &Fingerprint {
88 match self.hashes.get(index) {
89 Some(fingerprint) => fingerprint,
91 bug!("Could not find ICH for {:?}", index);
98 pub fn compute_incremental_hashes_map<'a, 'tcx: 'a>(tcx: TyCtxt<'a, 'tcx, 'tcx>)
99 -> IncrementalHashesMap {
100 let _ignore = tcx.dep_graph.in_ignore();
101 let krate = tcx.hir.krate();
102 let hash_spans = tcx.sess.opts.debuginfo != NoDebugInfo;
103 let mut visitor = HashItemsVisitor {
105 hashes: IncrementalHashesMap::new(),
106 def_path_hashes: DefPathHashes::new(tcx),
107 codemap: CachingCodemapView::new(tcx),
108 hash_spans: hash_spans,
110 record_time(&tcx.sess.perf_stats.incr_comp_hashes_time, || {
111 visitor.calculate_def_id(DefId::local(CRATE_DEF_INDEX), |v| {
112 v.hash_crate_root_module(krate);
114 krate.visit_all_item_likes(&mut visitor.as_deep_visitor());
116 for macro_def in krate.exported_macros.iter() {
117 visitor.calculate_node_id(macro_def.id,
118 |v| v.visit_macro_def(macro_def));
122 tcx.sess.perf_stats.incr_comp_hashes_count.set(visitor.hashes.len() as u64);
124 record_time(&tcx.sess.perf_stats.svh_time, || visitor.compute_crate_hash());
128 struct HashItemsVisitor<'a, 'tcx: 'a> {
129 tcx: TyCtxt<'a, 'tcx, 'tcx>,
130 def_path_hashes: DefPathHashes<'a, 'tcx>,
131 codemap: CachingCodemapView<'tcx>,
132 hashes: IncrementalHashesMap,
136 impl<'a, 'tcx> HashItemsVisitor<'a, 'tcx> {
137 fn calculate_node_id<W>(&mut self, id: ast::NodeId, walk_op: W)
138 where W: for<'v> FnMut(&mut StrictVersionHashVisitor<'v, 'a, 'tcx>)
140 let def_id = self.tcx.hir.local_def_id(id);
141 self.calculate_def_id(def_id, walk_op)
144 fn calculate_def_id<W>(&mut self, def_id: DefId, mut walk_op: W)
145 where W: for<'v> FnMut(&mut StrictVersionHashVisitor<'v, 'a, 'tcx>)
147 assert!(def_id.is_local());
148 debug!("HashItemsVisitor::calculate(def_id={:?})", def_id);
149 self.calculate_def_hash(DepNode::Hir(def_id), false, &mut walk_op);
150 self.calculate_def_hash(DepNode::HirBody(def_id), true, &mut walk_op);
153 fn calculate_def_hash<W>(&mut self,
154 dep_node: DepNode<DefId>,
157 where W: for<'v> FnMut(&mut StrictVersionHashVisitor<'v, 'a, 'tcx>)
159 let mut state = IchHasher::new();
160 walk_op(&mut StrictVersionHashVisitor::new(&mut state,
162 &mut self.def_path_hashes,
166 let bytes_hashed = state.bytes_hashed();
167 let item_hash = state.finish();
168 debug!("calculate_def_hash: dep_node={:?} hash={:?}", dep_node, item_hash);
169 self.hashes.insert(dep_node, item_hash);
171 let bytes_hashed = self.tcx.sess.perf_stats.incr_comp_bytes_hashed.get() +
173 self.tcx.sess.perf_stats.incr_comp_bytes_hashed.set(bytes_hashed);
176 fn compute_crate_hash(&mut self) {
177 let krate = self.tcx.hir.krate();
179 let mut crate_state = IchHasher::new();
181 let crate_disambiguator = self.tcx.sess.local_crate_disambiguator();
182 "crate_disambiguator".hash(&mut crate_state);
183 crate_disambiguator.as_str().len().hash(&mut crate_state);
184 crate_disambiguator.as_str().hash(&mut crate_state);
186 // add each item (in some deterministic order) to the overall
189 let def_path_hashes = &mut self.def_path_hashes;
190 let mut item_hashes: Vec<_> =
192 .map(|(item_dep_node, &item_hash)| {
193 // convert from a DepNode<DefId> tp a
194 // DepNode<u64> where the u64 is the
195 // hash of the def-id's def-path:
197 item_dep_node.map_def(|&did| Some(def_path_hashes.hash(did)))
199 (item_dep_node, item_hash)
202 item_hashes.sort(); // avoid artificial dependencies on item ordering
203 item_hashes.hash(&mut crate_state);
207 let mut visitor = StrictVersionHashVisitor::new(&mut crate_state,
209 &mut self.def_path_hashes,
213 visitor.hash_attributes(&krate.attrs);
216 let crate_hash = crate_state.finish();
217 self.hashes.insert(DepNode::Krate, crate_hash);
218 debug!("calculate_crate_hash: crate_hash={:?}", crate_hash);
223 impl<'a, 'tcx> Visitor<'tcx> for HashItemsVisitor<'a, 'tcx> {
224 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
225 NestedVisitorMap::None
228 fn visit_item(&mut self, item: &'tcx hir::Item) {
229 self.calculate_node_id(item.id, |v| v.visit_item(item));
230 visit::walk_item(self, item);
233 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem) {
234 self.calculate_node_id(trait_item.id, |v| v.visit_trait_item(trait_item));
235 visit::walk_trait_item(self, trait_item);
238 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem) {
239 self.calculate_node_id(impl_item.id, |v| v.visit_impl_item(impl_item));
240 visit::walk_impl_item(self, impl_item);