Auto merge of #44901 - michaelwoerister:on-demand-eval, r=nikomatsakis

incr.comp.: Switch to red/green change tracking, remove legacy system.

This PR finally switches incremental compilation to [red/green tracking](#42293) and completely removes the legacy dependency graph implementation -- which includes a few quite costly passes that are simply not needed with the new system anymore.

There's still some documentation to be done and there's certainly still lots of optimizing and tuning ahead -- but the foundation for red/green is in place with this PR. This has been in the making for a long time `:)`

r? @nikomatsakis
cc @alexcrichton, @rust-lang/compiler

src/librustc/dep_graph/dep_node.rs

@@ -65,8 +65,8 @@ use hir::map::DefPathHash;
 use hir::{HirId, ItemLocalId};
 
 use ich::Fingerprint;
-use ty::{TyCtxt, Instance, InstanceDef};
-use ty::fast_reject::SimplifiedType;
+use ty::{TyCtxt, Instance, InstanceDef, ParamEnvAnd, Ty};
+use ty::subst::Substs;
 use rustc_data_structures::stable_hasher::{StableHasher, HashStable};
 use ich::StableHashingContext;
 use std::fmt;
@@ -347,7 +347,7 @@ impl fmt::Debug for DepNode {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, "{:?}", self.kind)?;
 
-        if !self.kind.has_params() {
+        if !self.kind.has_params() && !self.kind.is_anon() {
             return Ok(());
         }
 
@@ -356,14 +356,14 @@ impl fmt::Debug for DepNode {
         ::ty::tls::with_opt(|opt_tcx| {
             if let Some(tcx) = opt_tcx {
                 if let Some(def_id) = self.extract_def_id(tcx) {
-                    write!(f, "{}", tcx.item_path_str(def_id))?;
+                    write!(f, "{}", tcx.def_path(def_id).to_string(tcx))?;
                 } else if let Some(ref s) = tcx.dep_graph.dep_node_debug_str(*self) {
                     write!(f, "{}", s)?;
                 } else {
-                    write!(f, "{:?}", self.hash)?;
+                    write!(f, "{}", self.hash)?;
                 }
             } else {
-                write!(f, "{:?}", self.hash)?;
+                write!(f, "{}", self.hash)?;
             }
             Ok(())
         })?;
@@ -430,7 +430,6 @@ define_dep_nodes!( <'tcx>
     [] RegionScopeTree(DefId),
     [] Coherence,
     [] CoherenceInherentImplOverlapCheck,
-    [] Resolve,
     [] CoherenceCheckTrait(DefId),
     [] PrivacyAccessLevels(CrateNum),
 
@@ -447,10 +446,8 @@ 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
@@ -484,32 +481,23 @@ define_dep_nodes!( <'tcx>
     [] TypeckBodiesKrate,
     [] TypeckTables(DefId),
     [] HasTypeckTables(DefId),
-    [anon] ConstEval,
+    [] ConstEval { param_env: ParamEnvAnd<'tcx, (DefId, &'tcx Substs<'tcx>)> },
     [] SymbolName(DefId),
     [] InstanceSymbolName { instance: Instance<'tcx> },
     [] SpecializationGraph(DefId),
     [] ObjectSafety(DefId),
 
-    [anon] IsCopy,
-    [anon] IsSized,
-    [anon] IsFreeze,
-    [anon] NeedsDrop,
-    [anon] Layout,
+    [] IsCopy { param_env: ParamEnvAnd<'tcx, Ty<'tcx>> },
+    [] IsSized { param_env: ParamEnvAnd<'tcx, Ty<'tcx>> },
+    [] IsFreeze { param_env: ParamEnvAnd<'tcx, Ty<'tcx>> },
+    [] NeedsDrop { param_env: ParamEnvAnd<'tcx, Ty<'tcx>> },
+    [] Layout { param_env: ParamEnvAnd<'tcx, Ty<'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`,
@@ -537,10 +525,6 @@ define_dep_nodes!( <'tcx>
     // trait-select node.
     [anon] TraitSelect,
 
-    // For proj. cache, we just keep a list of all def-ids, since it is
-    // not a hotspot.
-    [] ProjectionCache { def_ids: DefIdList },
-
     [] ParamEnv(DefId),
     [] DescribeDef(DefId),
     [] DefSpan(DefId),
@@ -598,7 +582,6 @@ define_dep_nodes!( <'tcx>
     [] MissingLangItems(CrateNum),
     [] ExternConstBody(DefId),
     [] VisibleParentMap,
-    [] IsDirectExternCrate(CrateNum),
     [] MissingExternCrateItem(CrateNum),
     [] UsedCrateSource(CrateNum),
     [] PostorderCnums,
@@ -618,6 +601,9 @@ 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 {
@@ -719,40 +705,6 @@ impl<'a, 'gcx: 'tcx + 'a, 'tcx: 'a> DepNodeParams<'a, 'gcx, 'tcx> for (DefId, De
     }
 }
 
-
-impl<'a, 'gcx: 'tcx + 'a, 'tcx: 'a> DepNodeParams<'a, 'gcx, 'tcx> for (DefIdList,) {
-    const CAN_RECONSTRUCT_QUERY_KEY: bool = false;
-
-    // We actually would not need to specialize the implementation of this
-    // method but it's faster to combine the hashes than to instantiate a full
-    // hashing context and stable-hashing state.
-    fn to_fingerprint(&self, tcx: TyCtxt) -> Fingerprint {
-        let mut fingerprint = Fingerprint::zero();
-
-        for &def_id in self.0.iter() {
-            let def_path_hash = tcx.def_path_hash(def_id);
-            fingerprint = fingerprint.combine(def_path_hash.0);
-        }
-
-        fingerprint
-    }
-
-    fn to_debug_str(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> String {
-        use std::fmt::Write;
-
-        let mut s = String::new();
-        write!(&mut s, "[").unwrap();
-
-        for &def_id in self.0.iter() {
-            write!(&mut s, "{}", tcx.def_path(def_id).to_string(tcx)).unwrap();
-        }
-
-        write!(&mut s, "]").unwrap();
-
-        s
-    }
-}
-
 impl<'a, 'gcx: 'tcx + 'a, 'tcx: 'a> DepNodeParams<'a, 'gcx, 'tcx> for (HirId,) {
     const CAN_RECONSTRUCT_QUERY_KEY: bool = false;
 
@@ -811,4 +763,3 @@ impl_stable_hash_for!(struct ::dep_graph::WorkProductId {
     hash
 });
 
-type DefIdList = Vec<DefId>;