incr.comp.: Re-execute queries during red/green marking in order to find out their color.

Author: michaelwoerister

src/librustc/dep_graph/dep_node.rs

@@ -66,7 +66,6 @@ use hir::{HirId, ItemLocalId};
 
 use ich::Fingerprint;
 use ty::{TyCtxt, Instance, InstanceDef};
-use ty::fast_reject::SimplifiedType;
 use rustc_data_structures::stable_hasher::{StableHasher, HashStable};
 use ich::StableHashingContext;
 use std::fmt;
@@ -430,7 +429,6 @@ define_dep_nodes!( <'tcx>
     [] RegionScopeTree(DefId),
     [] Coherence,
     [] CoherenceInherentImplOverlapCheck,
-    [] Resolve,
     [] CoherenceCheckTrait(DefId),
     [] PrivacyAccessLevels(CrateNum),
 
@@ -447,10 +445,8 @@ define_dep_nodes!( <'tcx>
     [] MirBorrowCheck(DefId),
     [] UnsafetyViolations(DefId),
 
-    [] RvalueCheck(DefId),
     [] Reachability,
     [] MirKeys,
-    [] TransWriteMetadata,
     [] CrateVariances,
 
     // Nodes representing bits of computed IR in the tcx. Each shared
@@ -498,18 +494,9 @@ define_dep_nodes!( <'tcx>
 
     // The set of impls for a given trait.
     [] TraitImpls(DefId),
-    [] RelevantTraitImpls(DefId, SimplifiedType),
 
     [] AllLocalTraitImpls,
 
-    // Nodes representing caches. To properly handle a true cache, we
-    // don't use a DepTrackingMap, but rather we push a task node.
-    // Otherwise the write into the map would be incorrectly
-    // attributed to the first task that happened to fill the cache,
-    // which would yield an overly conservative dep-graph.
-    [] TraitItems(DefId),
-    [] ReprHints(DefId),
-
     // Trait selection cache is a little funny. Given a trait
     // reference like `Foo: SomeTrait<Bar>`, there could be
     // arbitrarily many def-ids to map on in there (e.g., `Foo`,
@@ -598,7 +585,6 @@ define_dep_nodes!( <'tcx>
     [] MissingLangItems(CrateNum),
     [] ExternConstBody(DefId),
     [] VisibleParentMap,
-    [] IsDirectExternCrate(CrateNum),
     [] MissingExternCrateItem(CrateNum),
     [] UsedCrateSource(CrateNum),
     [] PostorderCnums,
@@ -618,6 +604,9 @@ define_dep_nodes!( <'tcx>
     [] CodegenUnit(InternedString),
     [] CompileCodegenUnit(InternedString),
     [] OutputFilenames,
+
+    // We use this for most things when incr. comp. is turned off.
+    [] Null,
 );
 
 trait DepNodeParams<'a, 'gcx: 'tcx + 'a, 'tcx: 'a> : fmt::Debug {

src/librustc/dep_graph/graph.rs

@@ -460,8 +460,9 @@ impl DepGraph {
 
         let mut current_deps = Vec::new();
 
-        for &dep_dep_node in prev_deps {
-            let dep_dep_node = &data.previous.index_to_node(dep_dep_node);
+        for &dep_dep_node_index in prev_deps {
+            let dep_dep_node = &data.previous.index_to_node(dep_dep_node_index);
+
             let dep_dep_node_color = data.colors.borrow().get(dep_dep_node).cloned();
             match dep_dep_node_color {
                 Some(DepNodeColor::Green(node_index)) => {
@@ -478,19 +479,42 @@ impl DepGraph {
                     return None
                 }
                 None => {
+                    if dep_dep_node.kind.is_input() {
+                        // This input does not exist anymore.
+                        debug_assert!(dep_dep_node.extract_def_id(tcx).is_none());
+                        return None;
+                    }
+
                     // We don't know the state of this dependency. Let's try to
                     // mark it green.
                     if let Some(node_index) = self.try_mark_green(tcx, dep_dep_node) {
                         current_deps.push(node_index);
                     } else {
-                        // We failed to mark it green. This can have various
-                        // reasons.
-                        return None
+                        // We failed to mark it green, so we try to force the query.
+                        if ::ty::maps::force_from_dep_node(tcx, dep_dep_node) {
+                            let dep_dep_node_color = data.colors.borrow().get(dep_dep_node).cloned();
+                            match dep_dep_node_color {
+                                Some(DepNodeColor::Green(node_index)) => {
+                                    current_deps.push(node_index);
+                                }
+                                Some(DepNodeColor::Red) => {
+                                    return None
+                                }
+                                None => {
+                                    bug!("try_mark_green() - Forcing the DepNode \
+                                          should have set its color")
+                                }
+                            }
+                        } else {
+                            // The DepNode could not be forced.
+                            return None
+                        }
                     }
                 }
             }
         }
 
+
         // If we got here without hitting a `return` that means that all
         // dependencies of this DepNode could be marked as green. Therefore we
         // can also mark this DepNode as green. We do so by...

src/librustc/ty/maps/mod.rs

@@ -56,6 +56,7 @@ use syntax::symbol::Symbol;
 #[macro_use]
 mod plumbing;
 use self::plumbing::*;
+pub use self::plumbing::force_from_dep_node;
 
 mod keys;
 pub use self::keys::Key;