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;
32 use std::hash::{Hash, Hasher};
33 use std::collections::hash_map::DefaultHasher;
34 use rustc::dep_graph::DepNode;
36 use rustc::hir::def_id::{CRATE_DEF_INDEX, DefId};
37 use rustc::hir::intravisit as visit;
38 use rustc::ty::TyCtxt;
39 use rustc_data_structures::fnv::FnvHashMap;
40 use rustc::util::common::record_time;
41 use rustc::session::config::DebugInfoLevel::NoDebugInfo;
43 use self::def_path_hash::DefPathHashes;
44 use self::svh_visitor::StrictVersionHashVisitor;
45 use self::caching_codemap_view::CachingCodemapView;
49 mod caching_codemap_view;
51 pub struct IncrementalHashesMap {
52 hashes: FnvHashMap<DepNode<DefId>, u64>,
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<FnvHashMap<DefId, u64>>,
62 impl IncrementalHashesMap {
63 pub fn new() -> IncrementalHashesMap {
64 IncrementalHashesMap {
66 prev_metadata_hashes: RefCell::new(FnvHashMap()),
70 pub fn insert(&mut self, k: DepNode<DefId>, v: u64) -> Option<u64> {
71 self.hashes.insert(k, v)
74 pub fn iter<'a>(&'a self) -> ::std::collections::hash_map::Iter<'a, DepNode<DefId>, u64> {
79 impl<'a> ::std::ops::Index<&'a DepNode<DefId>> for IncrementalHashesMap {
82 fn index(&self, index: &'a DepNode<DefId>) -> &u64 {
88 pub fn compute_incremental_hashes_map<'a, 'tcx: 'a>(tcx: TyCtxt<'a, 'tcx, 'tcx>)
89 -> IncrementalHashesMap {
90 let _ignore = tcx.dep_graph.in_ignore();
91 let krate = tcx.map.krate();
92 let hash_spans = tcx.sess.opts.debuginfo != NoDebugInfo;
93 let mut visitor = HashItemsVisitor {
95 hashes: IncrementalHashesMap::new(),
96 def_path_hashes: DefPathHashes::new(tcx),
97 codemap: CachingCodemapView::new(tcx),
98 hash_spans: hash_spans,
100 record_time(&tcx.sess.perf_stats.incr_comp_hashes_time, || {
101 visitor.calculate_def_id(DefId::local(CRATE_DEF_INDEX),
102 |v| visit::walk_crate(v, krate));
103 krate.visit_all_items(&mut visitor);
105 record_time(&tcx.sess.perf_stats.svh_time, || visitor.compute_crate_hash());
109 struct HashItemsVisitor<'a, 'tcx: 'a> {
110 tcx: TyCtxt<'a, 'tcx, 'tcx>,
111 def_path_hashes: DefPathHashes<'a, 'tcx>,
112 codemap: CachingCodemapView<'tcx>,
113 hashes: IncrementalHashesMap,
117 impl<'a, 'tcx> HashItemsVisitor<'a, 'tcx> {
118 fn calculate_node_id<W>(&mut self, id: ast::NodeId, walk_op: W)
119 where W: for<'v> FnMut(&mut StrictVersionHashVisitor<'v, 'a, 'tcx>)
121 let def_id = self.tcx.map.local_def_id(id);
122 self.calculate_def_id(def_id, walk_op)
125 fn calculate_def_id<W>(&mut self, def_id: DefId, mut walk_op: W)
126 where W: for<'v> FnMut(&mut StrictVersionHashVisitor<'v, 'a, 'tcx>)
128 assert!(def_id.is_local());
129 debug!("HashItemsVisitor::calculate(def_id={:?})", def_id);
130 // FIXME: this should use SHA1, not DefaultHasher. DefaultHasher is not
131 // built to avoid collisions.
132 let mut state = DefaultHasher::new();
133 walk_op(&mut StrictVersionHashVisitor::new(&mut state,
135 &mut self.def_path_hashes,
138 let item_hash = state.finish();
139 self.hashes.insert(DepNode::Hir(def_id), item_hash);
140 debug!("calculate_item_hash: def_id={:?} hash={:?}", def_id, item_hash);
143 fn compute_crate_hash(&mut self) {
144 let krate = self.tcx.map.krate();
146 let mut crate_state = DefaultHasher::new();
148 let crate_disambiguator = self.tcx.sess.local_crate_disambiguator();
149 "crate_disambiguator".hash(&mut crate_state);
150 crate_disambiguator.len().hash(&mut crate_state);
151 crate_disambiguator.hash(&mut crate_state);
153 // add each item (in some deterministic order) to the overall
156 let def_path_hashes = &mut self.def_path_hashes;
157 let mut item_hashes: Vec<_> =
159 .map(|(item_dep_node, &item_hash)| {
160 // convert from a DepNode<DefId> tp a
161 // DepNode<u64> where the u64 is the
162 // hash of the def-id's def-path:
164 item_dep_node.map_def(|&did| Some(def_path_hashes.hash(did)))
166 (item_dep_node, item_hash)
169 item_hashes.sort(); // avoid artificial dependencies on item ordering
170 item_hashes.hash(&mut crate_state);
174 let mut visitor = StrictVersionHashVisitor::new(&mut crate_state,
176 &mut self.def_path_hashes,
179 visitor.hash_attributes(&krate.attrs);
182 let crate_hash = crate_state.finish();
183 self.hashes.insert(DepNode::Krate, crate_hash);
184 debug!("calculate_crate_hash: crate_hash={:?}", crate_hash);
189 impl<'a, 'tcx> visit::Visitor<'tcx> for HashItemsVisitor<'a, 'tcx> {
190 fn visit_item(&mut self, item: &'tcx hir::Item) {
191 self.calculate_node_id(item.id, |v| v.visit_item(item));
192 visit::walk_item(self, item);
195 fn visit_foreign_item(&mut self, item: &'tcx hir::ForeignItem) {
196 self.calculate_node_id(item.id, |v| v.visit_foreign_item(item));
197 visit::walk_foreign_item(self, item);