Rollup merge of rust-lang#44364 - michaelwoerister:hash-all-the-things2, r=nikomatsakis

incr.comp.: Compute fingerprint for all query results.

This PR enables query result fingerprinting in incremental mode. This is an essential piece of infrastructure for red/green tracking. We don't do anything with the fingerprints yet but merging the infrastructure should protect it from bit-rotting and will make it easier to start measuring its performance impact (and thus let us determine if we should switch to a faster hashing algorithm rather sooner than later).

Note, this PR also includes the changes from rust-lang#43887 which I'm therefore closing. No need to re-review the first commit though.

r? @nikomatsakis

Author: alexcrichton

src/librustc/dep_graph/dep_node.rs

@@ -603,12 +603,12 @@ trait DepNodeParams<'a, 'gcx: 'tcx + 'a, 'tcx: 'a> : fmt::Debug {
 }
 
 impl<'a, 'gcx: 'tcx + 'a, 'tcx: 'a, T> DepNodeParams<'a, 'gcx, 'tcx> for T
-    where T: HashStable<StableHashingContext<'a, 'gcx, 'tcx>> + fmt::Debug
+    where T: HashStable<StableHashingContext<'gcx>> + fmt::Debug
 {
     default const CAN_RECONSTRUCT_QUERY_KEY: bool = false;
 
     default fn to_fingerprint(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Fingerprint {
-        let mut hcx = StableHashingContext::new(tcx);
+        let mut hcx = tcx.create_stable_hashing_context();
         let mut hasher = StableHasher::new();
 
         self.hash_stable(&mut hcx, &mut hasher);
@@ -633,6 +633,18 @@ impl<'a, 'gcx: 'tcx + 'a, 'tcx: 'a> DepNodeParams<'a, 'gcx, 'tcx> for (DefId,) {
     }
 }
 
+impl<'a, 'gcx: 'tcx + 'a, 'tcx: 'a> DepNodeParams<'a, 'gcx, 'tcx> for (DefIndex,) {
+    const CAN_RECONSTRUCT_QUERY_KEY: bool = true;
+
+    fn to_fingerprint(&self, tcx: TyCtxt) -> Fingerprint {
+        tcx.hir.definitions().def_path_hash(self.0).0
+    }
+
+    fn to_debug_str(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> String {
+        tcx.item_path_str(DefId::local(self.0))
+    }
+}
+
 impl<'a, 'gcx: 'tcx + 'a, 'tcx: 'a> DepNodeParams<'a, 'gcx, 'tcx> for (DefId, DefId) {
     const CAN_RECONSTRUCT_QUERY_KEY: bool = false;
 

src/librustc/dep_graph/graph.rs

@@ -9,11 +9,15 @@
 // except according to those terms.
 
 use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher,
+                                           StableHashingContextProvider};
 use session::config::OutputType;
 use std::cell::{Ref, RefCell};
 use std::rc::Rc;
 use util::common::{ProfileQueriesMsg, profq_msg};
 
+use ich::Fingerprint;
+
 use super::dep_node::{DepNode, DepKind, WorkProductId};
 use super::query::DepGraphQuery;
 use super::raii;
@@ -71,10 +75,6 @@ impl DepGraph {
         self.data.as_ref().map(|data| raii::IgnoreTask::new(&data.edges))
     }
 
-    pub fn in_task<'graph>(&'graph self, key: DepNode) -> Option<raii::DepTask<'graph>> {
-        self.data.as_ref().map(|data| raii::DepTask::new(&data.edges, key))
-    }
-
     pub fn with_ignore<OP,R>(&self, op: OP) -> R
         where OP: FnOnce() -> R
     {
@@ -109,24 +109,38 @@ impl DepGraph {
     ///   `arg` parameter.
     ///
     /// [README]: README.md
-    pub fn with_task<C, A, R>(&self,
-                              key: DepNode,
-                              cx: C,
-                              arg: A,
-                              task: fn(C, A) -> R)
-                              -> (R, DepNodeIndex)
-        where C: DepGraphSafe
+    pub fn with_task<C, A, R, HCX>(&self,
+                                   key: DepNode,
+                                   cx: C,
+                                   arg: A,
+                                   task: fn(C, A) -> R)
+                                   -> (R, DepNodeIndex)
+        where C: DepGraphSafe + StableHashingContextProvider<ContextType=HCX>,
+              R: HashStable<HCX>,
     {
         if let Some(ref data) = self.data {
             data.edges.borrow_mut().push_task(key);
             if cfg!(debug_assertions) {
                 profq_msg(ProfileQueriesMsg::TaskBegin(key.clone()))
             };
+
+            // In incremental mode, hash the result of the task. We don't
+            // do anything with the hash yet, but we are computing it
+            // anyway so that
+            //  - we make sure that the infrastructure works and
+            //  - we can get an idea of the runtime cost.
+            let mut hcx = cx.create_stable_hashing_context();
+
             let result = task(cx, arg);
             if cfg!(debug_assertions) {
                 profq_msg(ProfileQueriesMsg::TaskEnd)
             };
             let dep_node_index = data.edges.borrow_mut().pop_task(key);
+
+            let mut stable_hasher = StableHasher::new();
+            result.hash_stable(&mut hcx, &mut stable_hasher);
+            let _: Fingerprint = stable_hasher.finish();
+
             (result, dep_node_index)
         } else {
             (task(cx, arg), DepNodeIndex::INVALID)

src/librustc/dep_graph/safe.rs

@@ -58,6 +58,13 @@ impl<'a, A> DepGraphSafe for &'a A
 {
 }
 
+/// Mut ref to dep-graph-safe stuff should still be dep-graph-safe.
+impl<'a, A> DepGraphSafe for &'a mut A
+    where A: DepGraphSafe,
+{
+}
+
+
 /// No data here! :)
 impl DepGraphSafe for () {
 }

src/librustc/hir/map/mod.rs

@@ -247,7 +247,7 @@ pub struct Map<'hir> {
     /// plain old integers.
     map: Vec<MapEntry<'hir>>,
 
-    definitions: Definitions,
+    definitions: &'hir Definitions,
 
     /// Bodies inlined from other crates are cached here.
     inlined_bodies: RefCell<DefIdMap<&'hir Body>>,
@@ -304,8 +304,8 @@ impl<'hir> Map<'hir> {
     }
 
     #[inline]
-    pub fn definitions(&self) -> &Definitions {
-        &self.definitions
+    pub fn definitions(&self) -> &'hir Definitions {
+        self.definitions
     }
 
     pub fn def_key(&self, def_id: DefId) -> DefKey {
@@ -1013,7 +1013,7 @@ impl Named for TraitItem { fn name(&self) -> Name { self.name } }
 impl Named for ImplItem { fn name(&self) -> Name { self.name } }
 
 pub fn map_crate<'hir>(forest: &'hir mut Forest,
-                       definitions: Definitions)
+                       definitions: &'hir Definitions)
                        -> Map<'hir> {
     let map = {
         let mut collector = NodeCollector::root(&forest.krate,

src/librustc/ich/caching_codemap_view.rs

@@ -11,7 +11,6 @@
 use std::rc::Rc;
 use syntax::codemap::CodeMap;
 use syntax_pos::{BytePos, FileMap};
-use ty::TyCtxt;
 
 #[derive(Clone)]
 struct CacheEntry {
@@ -23,15 +22,14 @@ struct CacheEntry {
     file_index: usize,
 }
 
-pub struct CachingCodemapView<'tcx> {
-    codemap: &'tcx CodeMap,
+pub struct CachingCodemapView<'cm> {
+    codemap: &'cm CodeMap,
     line_cache: [CacheEntry; 3],
     time_stamp: usize,
 }
 
-impl<'gcx> CachingCodemapView<'gcx> {
-    pub fn new<'a, 'tcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>) -> CachingCodemapView<'gcx> {
-        let codemap = tcx.sess.codemap();
+impl<'cm> CachingCodemapView<'cm> {
+    pub fn new(codemap: &'cm CodeMap) -> CachingCodemapView<'cm> {
         let files = codemap.files();
         let first_file = files[0].clone();
         let entry = CacheEntry {