Auto merge of #44696 - michaelwoerister:fingerprints-in-dep-graph-3, r=nikomatsakis

incr.comp.: Move task result fingerprinting into DepGraph.

This PR
- makes the DepGraph store all `Fingerprints` of task results,
- allows `DepNode` to be marked as input nodes,
- makes HIR node hashing use the regular fingerprinting infrastructure,
- removes the now unused `IncrementalHashesMap`, and
- makes sure that `traits_in_scope_map` fingerprints are stable.

r? @nikomatsakis
cc @alexcrichton

Author: bors

src/librustc/dep_graph/dep_node.rs

@@ -80,14 +80,28 @@ macro_rules! erase {
     ($x:tt) => ({})
 }
 
-macro_rules! anon_attr_to_bool {
-    (anon) => (true)
+macro_rules! is_anon_attr {
+    (anon) => (true);
+    ($attr:ident) => (false);
+}
+
+macro_rules! is_input_attr {
+    (input) => (true);
+    ($attr:ident) => (false);
+}
+
+macro_rules! contains_anon_attr {
+    ($($attr:ident),*) => ({$(is_anon_attr!($attr) | )* false});
+}
+
+macro_rules! contains_input_attr {
+    ($($attr:ident),*) => ({$(is_input_attr!($attr) | )* false});
 }
 
 macro_rules! define_dep_nodes {
     (<$tcx:tt>
     $(
-        [$($anon:ident)*]
+        [$($attr:ident),* ]
         $variant:ident $(( $($tuple_arg:tt),* ))*
                        $({ $($struct_arg_name:ident : $struct_arg_ty:ty),* })*
       ,)*
@@ -105,7 +119,9 @@ macro_rules! define_dep_nodes {
                 match *self {
                     $(
                         DepKind :: $variant => {
-                            $(return !anon_attr_to_bool!($anon);)*
+                            if contains_anon_attr!($($attr),*) {
+                                return false;
+                            }
 
                             // tuple args
                             $({
@@ -126,15 +142,20 @@ macro_rules! define_dep_nodes {
                 }
             }
 
-            #[allow(unreachable_code)]
             #[inline]
-            pub fn is_anon<$tcx>(&self) -> bool {
+            pub fn is_anon(&self) -> bool {
                 match *self {
                     $(
-                        DepKind :: $variant => {
-                            $(return anon_attr_to_bool!($anon);)*
-                            false
-                        }
+                        DepKind :: $variant => { contains_anon_attr!($($attr),*) }
+                    )*
+                }
+            }
+
+            #[inline]
+            pub fn is_input(&self) -> bool {
+                match *self {
+                    $(
+                        DepKind :: $variant => { contains_input_attr!($($attr),*) }
                     )*
                 }
             }
@@ -366,6 +387,17 @@ impl DefId {
     }
 }
 
+impl DepKind {
+    #[inline]
+    pub fn fingerprint_needed_for_crate_hash(self) -> bool {
+        match self {
+            DepKind::HirBody |
+            DepKind::Krate => true,
+            _ => false,
+        }
+    }
+}
+
 define_dep_nodes!( <'tcx>
     // Represents the `Krate` as a whole (the `hir::Krate` value) (as
     // distinct from the krate module). This is basically a hash of
@@ -378,18 +410,17 @@ define_dep_nodes!( <'tcx>
     // suitable wrapper, you can use `tcx.dep_graph.ignore()` to gain
     // access to the krate, but you must remember to add suitable
     // edges yourself for the individual items that you read.
-    [] Krate,
-
-    // Represents the HIR node with the given node-id
-    [] Hir(DefId),
+    [input] Krate,
 
     // Represents the body of a function or method. The def-id is that of the
     // function/method.
-    [] HirBody(DefId),
+    [input] HirBody(DefId),
+
+    // Represents the HIR node with the given node-id
+    [input] Hir(DefId),
 
-    // Represents the metadata for a given HIR node, typically found
-    // in an extern crate.
-    [] MetaData(DefId),
+    // Represents metadata from an extern crate.
+    [input] MetaData(DefId),
 
     // Represents some artifact that we save to disk. Note that these
     // do not have a def-id as part of their identifier.
@@ -529,7 +560,7 @@ define_dep_nodes!( <'tcx>
     [] ExternCrate(DefId),
     [] LintLevels,
     [] Specializes { impl1: DefId, impl2: DefId },
-    [] InScopeTraits(DefIndex),
+    [input] InScopeTraits(DefIndex),
     [] ModuleExports(DefId),
     [] IsSanitizerRuntime(CrateNum),
     [] IsProfilerRuntime(CrateNum),

src/librustc/dep_graph/edges.rs

@@ -123,6 +123,7 @@ impl DepGraphEdges {
             reads
         } = popped_node {
             debug_assert_eq!(node, key);
+            debug_assert!(!node.kind.is_input() || reads.is_empty());
 
             let target_id = self.get_or_create_node(node);
 

src/librustc/dep_graph/graph.rs

@@ -26,7 +26,16 @@ use super::edges::{DepGraphEdges, DepNodeIndex};
 
 #[derive(Clone)]
 pub struct DepGraph {
-    data: Option<Rc<DepGraphData>>
+    data: Option<Rc<DepGraphData>>,
+
+    // At the moment we are using DepNode as key here. In the future it might
+    // be possible to use an IndexVec<DepNodeIndex, _> here. At the moment there
+    // are a few problems with that:
+    // - Some fingerprints are needed even if incr. comp. is disabled -- yet
+    //   we need to have a dep-graph to generate DepNodeIndices.
+    // - The architecture is still in flux and it's not clear what how to best
+    //   implement things.
+    fingerprints: Rc<RefCell<FxHashMap<DepNode, Fingerprint>>>
 }
 
 struct DepGraphData {
@@ -57,7 +66,8 @@ impl DepGraph {
                 }))
             } else {
                 None
-            }
+            },
+            fingerprints: Rc::new(RefCell::new(FxHashMap())),
         }
     }
 
@@ -139,11 +149,27 @@ impl DepGraph {
 
             let mut stable_hasher = StableHasher::new();
             result.hash_stable(&mut hcx, &mut stable_hasher);
-            let _: Fingerprint = stable_hasher.finish();
+
+            assert!(self.fingerprints
+                        .borrow_mut()
+                        .insert(key, stable_hasher.finish())
+                        .is_none());
 
             (result, dep_node_index)
         } else {
-            (task(cx, arg), DepNodeIndex::INVALID)
+            if key.kind.fingerprint_needed_for_crate_hash() {
+                let mut hcx = cx.create_stable_hashing_context();
+                let result = task(cx, arg);
+                let mut stable_hasher = StableHasher::new();
+                result.hash_stable(&mut hcx, &mut stable_hasher);
+                assert!(self.fingerprints
+                            .borrow_mut()
+                            .insert(key, stable_hasher.finish())
+                            .is_none());
+                (result, DepNodeIndex::INVALID)
+            } else {
+                (task(cx, arg), DepNodeIndex::INVALID)
+            }
         }
     }
 
@@ -195,6 +221,10 @@ impl DepGraph {
         }
     }
 
+    pub fn fingerprint_of(&self, dep_node: &DepNode) -> Option<Fingerprint> {
+        self.fingerprints.borrow().get(dep_node).cloned()
+    }
+
     /// Indicates that a previous work product exists for `v`. This is
     /// invoked during initial start-up based on what nodes are clean
     /// (and what files exist in the incr. directory).