Annotate the compiler with information about what it is doing when.

src/librustc/lint/context.rs

@@ -25,6 +25,7 @@
 //! for all lint attributes.
 use self::TargetLint::*;
 
+use dep_graph::DepNode;
 use middle::privacy::AccessLevels;
 use middle::ty;
 use session::{early_error, Session};
@@ -1071,6 +1072,8 @@ impl LateLintPass for GatherNodeLevels {
 ///
 /// Consumes the `lint_store` field of the `Session`.
 pub fn check_crate(tcx: &ty::ctxt, access_levels: &AccessLevels) {
+    let _task = tcx.dep_graph.in_task(DepNode::LateLintCheck);
+
     let krate = tcx.map.krate();
     let mut cx = LateContext::new(tcx, krate, access_levels);
 

src/librustc/middle/check_const.rs

@@ -24,6 +24,7 @@
 // - It's not possible to take the address of a static item with unsafe interior. This is enforced
 // by borrowck::gather_loans
 
+use dep_graph::DepNode;
 use middle::ty::cast::{CastKind};
 use middle::const_eval::{self, ConstEvalErr};
 use middle::const_eval::ErrKind::IndexOpFeatureGated;
@@ -842,13 +843,12 @@ fn check_adjustments<'a, 'tcx>(v: &mut CheckCrateVisitor<'a, 'tcx>, e: &hir::Exp
 }
 
 pub fn check_crate(tcx: &ty::ctxt) {
-    tcx.map.krate().visit_all_items(&mut CheckCrateVisitor {
+    tcx.visit_all_items_in_krate(DepNode::CheckConst, &mut CheckCrateVisitor {
         tcx: tcx,
         mode: Mode::Var,
         qualif: ConstQualif::NOT_CONST,
         rvalue_borrows: NodeMap()
     });
-
     tcx.sess.abort_if_errors();
 }
 

src/librustc/middle/check_match.rs

@@ -12,6 +12,7 @@ pub use self::Constructor::*;
 use self::Usefulness::*;
 use self::WitnessPreference::*;
 
+use dep_graph::DepNode;
 use middle::const_eval::{compare_const_vals, ConstVal};
 use middle::const_eval::{eval_const_expr, eval_const_expr_partial};
 use middle::const_eval::{const_expr_to_pat, lookup_const_by_id};
@@ -155,7 +156,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for MatchCheckCtxt<'a, 'tcx> {
 }
 
 pub fn check_crate(tcx: &ty::ctxt) {
-    tcx.map.krate().visit_all_items(&mut MatchCheckCtxt {
+    tcx.visit_all_items_in_krate(DepNode::MatchCheck, &mut MatchCheckCtxt {
         tcx: tcx,
         param_env: tcx.empty_parameter_environment(),
     });

src/librustc/middle/check_rvalues.rs

@@ -11,21 +11,21 @@
 // Checks that all rvalues in a crate have statically known size. check_crate
 // is the public starting point.
 
+use dep_graph::DepNode;
 use middle::expr_use_visitor as euv;
 use middle::infer;
 use middle::mem_categorization as mc;
 use middle::ty::ParameterEnvironment;
 use middle::ty;
 
-use syntax::ast;
 use rustc_front::hir;
-use syntax::codemap::Span;
 use rustc_front::intravisit;
+use syntax::ast;
+use syntax::codemap::Span;
 
-pub fn check_crate(tcx: &ty::ctxt,
-                   krate: &hir::Crate) {
+pub fn check_crate(tcx: &ty::ctxt) {
     let mut rvcx = RvalueContext { tcx: tcx };
-    krate.visit_all_items(&mut rvcx);
+    tcx.visit_all_items_in_krate(DepNode::RvalueCheck, &mut rvcx);
 }
 
 struct RvalueContext<'a, 'tcx: 'a> {

src/librustc/middle/dead.rs

@@ -12,6 +12,7 @@
 // closely. The idea is that all reachable symbols are live, codes called
 // from live codes are live, and everything else is dead.
 
+use dep_graph::DepNode;
 use front::map as ast_map;
 use rustc_front::hir;
 use rustc_front::intravisit::{self, Visitor};
@@ -590,6 +591,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for DeadVisitor<'a, 'tcx> {
 }
 
 pub fn check_crate(tcx: &ty::ctxt, access_levels: &privacy::AccessLevels) {
+    let _task = tcx.dep_graph.in_task(DepNode::DeadCheck);
     let krate = tcx.map.krate();
     let live_symbols = find_live(tcx, access_levels, krate);
     let mut visitor = DeadVisitor { tcx: tcx, live_symbols: live_symbols };

src/librustc/middle/intrinsicck.rs

@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+use dep_graph::DepNode;
 use middle::def::DefFn;
 use middle::def_id::DefId;
 use middle::subst::{Subst, Substs, EnumeratedItems};
@@ -29,7 +30,7 @@ pub fn check_crate(tcx: &ctxt) {
         dummy_sized_ty: tcx.types.isize,
         dummy_unsized_ty: tcx.mk_slice(tcx.types.isize),
     };
-    tcx.map.krate().visit_all_items(&mut visitor);
+    tcx.visit_all_items_in_krate(DepNode::IntrinsicCheck, &mut visitor);
 }
 
 struct IntrinsicCheckingVisitor<'a, 'tcx: 'a> {

src/librustc/middle/reachable.rs

@@ -15,6 +15,7 @@
 // makes all other generics or inline functions that it references
 // reachable as well.
 
+use dep_graph::DepNode;
 use front::map as ast_map;
 use middle::def;
 use middle::def_id::DefId;
@@ -349,6 +350,7 @@ impl<'a, 'v> Visitor<'v> for CollectPrivateImplItemsVisitor<'a> {
 pub fn find_reachable(tcx: &ty::ctxt,
                       access_levels: &privacy::AccessLevels)
                       -> NodeSet {
+    let _task = tcx.dep_graph.in_task(DepNode::Reachability);
 
     let mut reachable_context = ReachableContext::new(tcx);
 

src/librustc/middle/stability.rs

@@ -13,6 +13,7 @@
 
 pub use self::StabilityLevel::*;
 
+use dep_graph::DepNode;
 use session::Session;
 use lint;
 use middle::cstore::{CrateStore, LOCAL_CRATE};
@@ -328,6 +329,7 @@ impl<'tcx> Index<'tcx> {
 /// features used.
 pub fn check_unstable_api_usage(tcx: &ty::ctxt)
                                 -> FnvHashMap<InternedString, StabilityLevel> {
+    let _task = tcx.dep_graph.in_task(DepNode::StabilityCheck);
     let ref active_lib_features = tcx.sess.features.borrow().declared_lib_features;
 
     // Put the active features into a map for quick lookup
@@ -341,8 +343,7 @@ pub fn check_unstable_api_usage(tcx: &ty::ctxt)
     };
     intravisit::walk_crate(&mut checker, tcx.map.krate());
 
-    let used_features = checker.used_features;
-    return used_features;
+    checker.used_features
 }
 
 struct Checker<'a, 'tcx: 'a> {

src/librustc/middle/traits/mod.rs

@@ -15,10 +15,12 @@ pub use self::FulfillmentErrorCode::*;
 pub use self::Vtable::*;
 pub use self::ObligationCauseCode::*;
 
+use dep_graph::DepNode;
 use middle::def_id::DefId;
 use middle::free_region::FreeRegionMap;
 use middle::subst;
 use middle::ty::{self, HasTypeFlags, Ty};
+use middle::ty::fast_reject;
 use middle::ty::fold::TypeFoldable;
 use middle::infer::{self, fixup_err_to_string, InferCtxt};
 
@@ -599,6 +601,18 @@ impl<'tcx> FulfillmentError<'tcx> {
 }
 
 impl<'tcx> TraitObligation<'tcx> {
+    /// Creates the dep-node for selecting/evaluating this trait reference.
+    fn dep_node(&self, tcx: &ty::ctxt<'tcx>) -> DepNode {
+        let simplified_ty =
+            fast_reject::simplify_type(tcx,
+                                       self.predicate.skip_binder().self_ty(), // (*)
+                                       true);
+
+        // (*) skip_binder is ok because `simplify_type` doesn't care about regions
+
+        DepNode::TraitSelect(self.predicate.def_id(), simplified_ty)
+    }
+
     fn self_ty(&self) -> ty::Binder<Ty<'tcx>> {
         ty::Binder(self.predicate.skip_binder().self_ty())
     }

src/librustc/middle/traits/select.rs

@@ -310,6 +310,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         debug!("select({:?})", obligation);
         assert!(!obligation.predicate.has_escaping_regions());
 
+        let dep_node = obligation.dep_node(self.tcx());
+        let _task = self.tcx().dep_graph.in_task(dep_node);
+
         let stack = self.push_stack(TraitObligationStackList::empty(), obligation);
         match try!(self.candidate_from_obligation(&stack)) {
             None => {
@@ -411,7 +414,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     /// accurate if inference variables are involved.
     pub fn evaluate_obligation_conservatively(&mut self,
                                               obligation: &PredicateObligation<'tcx>)
-                               -> bool
+                                              -> bool
     {
         debug!("evaluate_obligation_conservatively({:?})",
                obligation);

src/librustc/middle/ty/mod.rs

@@ -51,6 +51,7 @@ use syntax::parse::token::{InternedString, special_idents};
 
 use rustc_front::hir;
 use rustc_front::hir::{ItemImpl, ItemTrait};
+use rustc_front::intravisit::Visitor;
 
 pub use self::sty::{Binder, DebruijnIndex};
 pub use self::sty::{BuiltinBound, BuiltinBounds, ExistentialBounds};
@@ -1946,7 +1947,14 @@ fn lookup_locally_or_in_crate_store<V, F>(descr: &str,
         panic!("No def'n found for {:?} in tcx.{}", def_id, descr);
     }
     let v = load_external();
-    map.borrow_mut().insert(def_id, v.clone());
+
+    // Don't consider this a write from the current task, since we are
+    // loading from another crate. (Note that the current task will
+    // already have registered a read in the call to `get` above.)
+    dep_graph.with_ignore(|| {
+        map.borrow_mut().insert(def_id, v.clone());
+    });
+
     v
 }
 
@@ -2458,6 +2466,10 @@ impl<'tcx> ctxt<'tcx> {
             return
         }
 
+        // The primitive is not local, hence we are reading this out
+        // of metadata.
+        let _ignore = self.dep_graph.in_ignore();
+
         if self.populated_external_primitive_impls.borrow().contains(&primitive_def_id) {
             return
         }
@@ -2480,6 +2492,10 @@ impl<'tcx> ctxt<'tcx> {
             return
         }
 
+        // The type is not local, hence we are reading this out of
+        // metadata and don't need to track edges.
+        let _ignore = self.dep_graph.in_ignore();
+
         if self.populated_external_types.borrow().contains(&type_id) {
             return
         }
@@ -2505,6 +2521,10 @@ impl<'tcx> ctxt<'tcx> {
             return
         }
 
+        // The type is not local, hence we are reading this out of
+        // metadata and don't need to track edges.
+        let _ignore = self.dep_graph.in_ignore();
+
         let def = self.lookup_trait_def(trait_id);
         if def.flags.get().intersects(TraitFlags::IMPLS_VALID) {
             return;
@@ -2727,6 +2747,15 @@ impl<'tcx> ctxt<'tcx> {
     pub fn upvar_capture(&self, upvar_id: ty::UpvarId) -> Option<ty::UpvarCapture> {
         Some(self.tables.borrow().upvar_capture_map.get(&upvar_id).unwrap().clone())
     }
+
+
+    pub fn visit_all_items_in_krate<V,F>(&self,
+                                         dep_node_fn: F,
+                                         visitor: &mut V)
+        where F: FnMut(DefId) -> DepNode, V: Visitor<'tcx>
+    {
+        dep_graph::visit_all_items_in_krate(self, dep_node_fn, visitor);
+    }
 }
 
 /// The category of explicit self.

src/librustc/session/config.rs

@@ -125,6 +125,8 @@ pub struct Options {
     pub parse_only: bool,
     pub no_trans: bool,
     pub treat_err_as_bug: bool,
+    pub incremental_compilation: bool,
+    pub dump_dep_graph: bool,
     pub no_analysis: bool,
     pub debugging_opts: DebuggingOptions,
     pub prints: Vec<PrintRequest>,
@@ -234,6 +236,8 @@ pub fn basic_options() -> Options {
         parse_only: false,
         no_trans: false,
         treat_err_as_bug: false,
+        incremental_compilation: false,
+        dump_dep_graph: false,
         no_analysis: false,
         debugging_opts: basic_debugging_options(),
         prints: Vec::new(),
@@ -606,6 +610,10 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
           "run all passes except translation; no output"),
     treat_err_as_bug: bool = (false, parse_bool,
           "treat all errors that occur as bugs"),
+    incr_comp: bool = (false, parse_bool,
+          "enable incremental compilation (experimental)"),
+    dump_dep_graph: bool = (false, parse_bool,
+          "dump the dependency graph to $RUST_DEP_GRAPH (default: /tmp/dep_graph.gv)"),
     no_analysis: bool = (false, parse_bool,
           "parse and expand the source, but run no analysis"),
     extra_plugins: Vec<String> = (Vec::new(), parse_list,
@@ -932,6 +940,8 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
     let parse_only = debugging_opts.parse_only;
     let no_trans = debugging_opts.no_trans;
     let treat_err_as_bug = debugging_opts.treat_err_as_bug;
+    let incremental_compilation = debugging_opts.incr_comp;
+    let dump_dep_graph = debugging_opts.dump_dep_graph;
     let no_analysis = debugging_opts.no_analysis;
 
     if debugging_opts.debug_llvm {
@@ -1106,6 +1116,8 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
         parse_only: parse_only,
         no_trans: no_trans,
         treat_err_as_bug: treat_err_as_bug,
+        incremental_compilation: incremental_compilation || dump_dep_graph,
+        dump_dep_graph: dump_dep_graph,
         no_analysis: no_analysis,
         debugging_opts: debugging_opts,
         prints: prints,