Rollup merge of #41063 - nikomatsakis:issue-40746-always-exec-loops, r=eddyb

remove unnecessary tasks

Remove various unnecessary tasks. All of these are "always execute" tasks that don't do any writes to tracked state (or else an assert would trigger, anyhow). In some cases, they issue lints or errors, but we''ll deal with that -- and anyway side-effects outside of a task don't cause problems for anything that I can see.

The one non-trivial refactoring here is the borrowck conversion, which adds the requirement to go from a `DefId` to a `BodyId`. I tried to make a useful helper here.

r? @eddyb

cc #40746
cc @cramertj @michaelwoerister

10 files changed, 42 insertions, 34 deletions

diff --git a/src/librustc/dep_graph/dep_node.rs b/src/librustc/dep_graph/dep_node.rs
index 5aea2bcaa4f..59d04ea8c77 100644
--- a/src/librustc/dep_graph/dep_node.rs
+++ b/src/librustc/dep_graph/dep_node.rs
@@ -57,17 +57,13 @@ pub enum DepNode<D: Clone + Debug> {
 
     // Represents different phases in the compiler.
     CollectLanguageItems,
-    CheckStaticRecursion,
     ResolveLifetimes,
     RegionResolveCrate,
-    CheckLoops,
     PluginRegistrar,
     StabilityIndex,
     CollectItem(D),
     CollectItemSig(D),
     Coherence,
-    EffectCheck,
-    Liveness,
     Resolve,
     EntryPoint,
     CheckEntryFn,
@@ -216,15 +212,11 @@ impl<D: Clone + Debug> DepNode<D> {
             MirKrate => Some(MirKrate),
             TypeckBodiesKrate => Some(TypeckBodiesKrate),
             CollectLanguageItems => Some(CollectLanguageItems),
-            CheckStaticRecursion => Some(CheckStaticRecursion),
             ResolveLifetimes => Some(ResolveLifetimes),
             RegionResolveCrate => Some(RegionResolveCrate),
-            CheckLoops => Some(CheckLoops),
             PluginRegistrar => Some(PluginRegistrar),
             StabilityIndex => Some(StabilityIndex),
             Coherence => Some(Coherence),
-            EffectCheck => Some(EffectCheck),
-            Liveness => Some(Liveness),
             Resolve => Some(Resolve),
             EntryPoint => Some(EntryPoint),
             CheckEntryFn => Some(CheckEntryFn),
diff --git a/src/librustc/hir/map/mod.rs b/src/librustc/hir/map/mod.rs
index d7aa36b24f9..cfafec00ae2 100644
--- a/src/librustc/hir/map/mod.rs
+++ b/src/librustc/hir/map/mod.rs
@@ -442,6 +442,27 @@ impl<'hir> Map<'hir> {
         self.local_def_id(self.body_owner(id))
     }
 
+    /// Given a body owner's id, returns the `BodyId` associated with it.
+    pub fn body_owned_by(&self, id: NodeId) -> BodyId {
+        if let Some(entry) = self.find_entry(id) {
+            if let Some(body_id) = entry.associated_body() {
+                // For item-like things and closures, the associated
+                // body has its own distinct id, and that is returned
+                // by `associated_body`.
+                body_id
+            } else {
+                // For some expressions, the expression is its own body.
+                if let EntryExpr(_, expr) = entry {
+                    BodyId { node_id: expr.id }
+                } else {
+                    span_bug!(self.span(id), "id `{}` has no associated body", id);
+                }
+            }
+        } else {
+            bug!("no entry for id `{}`", id)
+        }
+    }
+
     pub fn ty_param_owner(&self, id: NodeId) -> NodeId {
         match self.get(id) {
             NodeItem(&Item { node: ItemTrait(..), .. }) => id,
diff --git a/src/librustc/middle/effect.rs b/src/librustc/middle/effect.rs
index 5af8e7e52d8..d2b8ed8c297 100644
--- a/src/librustc/middle/effect.rs
+++ b/src/librustc/middle/effect.rs
@@ -12,7 +12,6 @@
 //! `unsafe`.
 use self::RootUnsafeContext::*;
 
-use dep_graph::DepNode;
 use ty::{self, Ty, TyCtxt};
 use ty::MethodCall;
 use lint;
@@ -241,8 +240,6 @@ impl<'a, 'tcx> Visitor<'tcx> for EffectCheckVisitor<'a, 'tcx> {
 }
 
 pub fn check_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
-    let _task = tcx.dep_graph.in_task(DepNode::EffectCheck);
-
     let mut visitor = EffectCheckVisitor {
         tcx: tcx,
         tables: &ty::TypeckTables::empty(),
diff --git a/src/librustc/middle/liveness.rs b/src/librustc/middle/liveness.rs
index 7cae08efc0d..b7da8480c1c 100644
--- a/src/librustc/middle/liveness.rs
+++ b/src/librustc/middle/liveness.rs
@@ -109,7 +109,6 @@ use self::LoopKind::*;
 use self::LiveNodeKind::*;
 use self::VarKind::*;
 
-use dep_graph::DepNode;
 use hir::def::*;
 use ty::{self, TyCtxt, ParameterEnvironment};
 use traits::{self, Reveal};
@@ -196,7 +195,6 @@ impl<'a, 'tcx> Visitor<'tcx> for IrMaps<'a, 'tcx> {
 }
 
 pub fn check_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
-    let _task = tcx.dep_graph.in_task(DepNode::Liveness);
     tcx.hir.krate().visit_all_item_likes(&mut IrMaps::new(tcx).as_deep_visitor());
     tcx.sess.abort_if_errors();
 }
diff --git a/src/librustc/ty/maps.rs b/src/librustc/ty/maps.rs
index 823bdc9e092..868ccad8a3a 100644
--- a/src/librustc/ty/maps.rs
+++ b/src/librustc/ty/maps.rs
@@ -429,6 +429,8 @@ define_maps! { <'tcx>
 
     pub coherent_trait: coherent_trait_dep_node((CrateNum, DefId)) -> (),
 
+    pub borrowck: BorrowCheck(DefId) -> (),
+
     /// Gets a complete map from all types to their inherent impls.
     /// Not meant to be used directly outside of coherence.
     /// (Defined only for LOCAL_CRATE)
diff --git a/src/librustc_borrowck/borrowck/mod.rs b/src/librustc_borrowck/borrowck/mod.rs
index 0915c57b588..142286bd834 100644
--- a/src/librustc_borrowck/borrowck/mod.rs
+++ b/src/librustc_borrowck/borrowck/mod.rs
@@ -22,7 +22,6 @@ pub use self::mir::elaborate_drops::ElaborateDrops;
 
 use self::InteriorKind::*;
 
-use rustc::dep_graph::DepNode;
 use rustc::hir::map as hir_map;
 use rustc::hir::map::blocks::FnLikeNode;
 use rustc::cfg;
@@ -37,12 +36,13 @@ use rustc::middle::mem_categorization::Categorization;
 use rustc::middle::mem_categorization::ImmutabilityBlame;
 use rustc::middle::region;
 use rustc::ty::{self, TyCtxt};
+use rustc::ty::maps::Providers;
 
 use std::fmt;
 use std::rc::Rc;
 use std::hash::{Hash, Hasher};
 use syntax::ast;
-use syntax_pos::{MultiSpan, Span};
+use syntax_pos::{DUMMY_SP, MultiSpan, Span};
 use errors::DiagnosticBuilder;
 
 use rustc::hir;
@@ -62,16 +62,16 @@ pub struct LoanDataFlowOperator;
 pub type LoanDataFlow<'a, 'tcx> = DataFlowContext<'a, 'tcx, LoanDataFlowOperator>;
 
 pub fn check_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
-    tcx.dep_graph.with_task(DepNode::BorrowCheckKrate, tcx, (), check_crate_task);
-
-    fn check_crate_task<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, (): ()) {
-        tcx.visit_all_bodies_in_krate(|body_owner_def_id, body_id| {
-            tcx.dep_graph.with_task(DepNode::BorrowCheck(body_owner_def_id),
-                                    tcx,
-                                    body_id,
-                                    borrowck_fn);
-        });
-    }
+    tcx.visit_all_bodies_in_krate(|body_owner_def_id, _body_id| {
+        ty::queries::borrowck::get(tcx, DUMMY_SP, body_owner_def_id);
+    });
+}
+
+pub fn provide(providers: &mut Providers) {
+    *providers = Providers {
+        borrowck,
+        ..*providers
+    };
 }
 
 /// Collection of conclusions determined via borrow checker analyses.
@@ -81,11 +81,11 @@ pub struct AnalysisData<'a, 'tcx: 'a> {
     pub move_data: move_data::FlowedMoveData<'a, 'tcx>,
 }
 
-fn borrowck_fn<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, body_id: hir::BodyId) {
-    debug!("borrowck_fn(body_id={:?})", body_id);
+fn borrowck<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, owner_def_id: DefId) {
+    debug!("borrowck(body_owner_def_id={:?})", owner_def_id);
 
-    let owner_id = tcx.hir.body_owner(body_id);
-    let owner_def_id = tcx.hir.local_def_id(owner_id);
+    let owner_id = tcx.hir.as_local_node_id(owner_def_id).unwrap();
+    let body_id = tcx.hir.body_owned_by(owner_id);
     let attributes = tcx.get_attrs(owner_def_id);
     let tables = tcx.item_tables(owner_def_id);
 
diff --git a/src/librustc_borrowck/lib.rs b/src/librustc_borrowck/lib.rs
index d3b22884a3d..a1d3357faf5 100644
--- a/src/librustc_borrowck/lib.rs
+++ b/src/librustc_borrowck/lib.rs
@@ -51,4 +51,6 @@ mod borrowck;
 
 pub mod graphviz;
 
+pub use borrowck::provide;
+
 __build_diagnostic_array! { librustc_borrowck, DIAGNOSTICS }
diff --git a/src/librustc_driver/driver.rs b/src/librustc_driver/driver.rs
index bdb05d06b0b..7556aa70752 100644
--- a/src/librustc_driver/driver.rs
+++ b/src/librustc_driver/driver.rs
@@ -891,6 +891,7 @@ pub fn phase_3_run_analysis_passes<'tcx, F, R>(sess: &'tcx Session,
     let mut local_providers = ty::maps::Providers::default();
     mir::provide(&mut local_providers);
     rustc_privacy::provide(&mut local_providers);
+    borrowck::provide(&mut local_providers);
     typeck::provide(&mut local_providers);
     ty::provide(&mut local_providers);
     reachable::provide(&mut local_providers);
diff --git a/src/librustc_passes/loops.rs b/src/librustc_passes/loops.rs
index 421181c68c4..2ea235af103 100644
--- a/src/librustc_passes/loops.rs
+++ b/src/librustc_passes/loops.rs
@@ -11,7 +11,6 @@ use self::Context::*;
 
 use rustc::session::Session;
 
-use rustc::dep_graph::DepNode;
 use rustc::hir::map::Map;
 use rustc::hir::intravisit::{self, Visitor, NestedVisitorMap};
 use rustc::hir;
@@ -50,7 +49,6 @@ struct CheckLoopVisitor<'a, 'hir: 'a> {
 }
 
 pub fn check_crate(sess: &Session, map: &Map) {
-    let _task = map.dep_graph.in_task(DepNode::CheckLoops);
     let krate = map.krate();
     krate.visit_all_item_likes(&mut CheckLoopVisitor {
         sess: sess,
diff --git a/src/librustc_passes/static_recursion.rs b/src/librustc_passes/static_recursion.rs
index fc05471ead3..d0bf49b7b33 100644
--- a/src/librustc_passes/static_recursion.rs
+++ b/src/librustc_passes/static_recursion.rs
@@ -11,7 +11,6 @@
 // This compiler pass detects constants that refer to themselves
 // recursively.
 
-use rustc::dep_graph::DepNode;
 use rustc::hir::map as hir_map;
 use rustc::session::{CompileResult, Session};
 use rustc::hir::def::{Def, CtorKind};
@@ -88,8 +87,6 @@ impl<'a, 'hir: 'a> Visitor<'hir> for CheckCrateVisitor<'a, 'hir> {
 }
 
 pub fn check_crate<'hir>(sess: &Session, hir_map: &hir_map::Map<'hir>) -> CompileResult {
-    let _task = hir_map.dep_graph.in_task(DepNode::CheckStaticRecursion);
-
     let mut visitor = CheckCrateVisitor {
         sess: sess,
         hir_map: hir_map,