Auto merge of rust-lang#45137 - theotherjimmy:vtable-methods-query, r=nikomatsakis

Queryify Vtable methods

This query might come with a downside: It converts an iterator to a Vec, which may increase the working set of rustc on programs that use many many traits (I think that's where this is used).

Author: bors

src/librustc/dep_graph/dep_node.rs

@@ -506,6 +506,7 @@ define_dep_nodes!( <'tcx>
     [] SpecializationGraph(DefId),
     [] ObjectSafety(DefId),
     [] FulfillObligation { param_env: ParamEnv<'tcx>, trait_ref: PolyTraitRef<'tcx> },
+    [] VtableMethods { trait_ref: PolyTraitRef<'tcx> },
 
     [] IsCopy { param_env: ParamEnvAnd<'tcx, Ty<'tcx>> },
     [] IsSized { param_env: ParamEnvAnd<'tcx, Ty<'tcx>> },

src/librustc/traits/mod.rs

@@ -650,53 +650,55 @@ pub fn normalize_and_test_predicates<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 /// Given a trait `trait_ref`, iterates the vtable entries
 /// that come from `trait_ref`, including its supertraits.
 #[inline] // FIXME(#35870) Avoid closures being unexported due to impl Trait.
-pub fn get_vtable_methods<'a, 'tcx>(
+fn vtable_methods<'a, 'tcx>(
     tcx: TyCtxt<'a, 'tcx, 'tcx>,
     trait_ref: ty::PolyTraitRef<'tcx>)
-    -> impl Iterator<Item=Option<(DefId, &'tcx Substs<'tcx>)>> + 'a
+    -> Rc<Vec<Option<(DefId, &'tcx Substs<'tcx>)>>>
 {
-    debug!("get_vtable_methods({:?})", trait_ref);
-
-    supertraits(tcx, trait_ref).flat_map(move |trait_ref| {
-        let trait_methods = tcx.associated_items(trait_ref.def_id())
-            .filter(|item| item.kind == ty::AssociatedKind::Method);
-
-        // Now list each method's DefId and Substs (for within its trait).
-        // If the method can never be called from this object, produce None.
-        trait_methods.map(move |trait_method| {
-            debug!("get_vtable_methods: trait_method={:?}", trait_method);
-            let def_id = trait_method.def_id;
-
-            // Some methods cannot be called on an object; skip those.
-            if !tcx.is_vtable_safe_method(trait_ref.def_id(), &trait_method) {
-                debug!("get_vtable_methods: not vtable safe");
-                return None;
-            }
-
-            // the method may have some early-bound lifetimes, add
-            // regions for those
-            let substs = Substs::for_item(tcx, def_id,
-                                          |_, _| tcx.types.re_erased,
-                                          |def, _| trait_ref.substs().type_for_def(def));
-
-            // the trait type may have higher-ranked lifetimes in it;
-            // so erase them if they appear, so that we get the type
-            // at some particular call site
-            let substs = tcx.erase_late_bound_regions_and_normalize(&ty::Binder(substs));
-
-            // It's possible that the method relies on where clauses that
-            // do not hold for this particular set of type parameters.
-            // Note that this method could then never be called, so we
-            // do not want to try and trans it, in that case (see #23435).
-            let predicates = tcx.predicates_of(def_id).instantiate_own(tcx, substs);
-            if !normalize_and_test_predicates(tcx, predicates.predicates) {
-                debug!("get_vtable_methods: predicates do not hold");
-                return None;
-            }
-
-            Some((def_id, substs))
-        })
-    })
+    debug!("vtable_methods({:?})", trait_ref);
+
+    Rc::new(
+        supertraits(tcx, trait_ref).flat_map(move |trait_ref| {
+            let trait_methods = tcx.associated_items(trait_ref.def_id())
+                .filter(|item| item.kind == ty::AssociatedKind::Method);
+
+            // Now list each method's DefId and Substs (for within its trait).
+            // If the method can never be called from this object, produce None.
+            trait_methods.map(move |trait_method| {
+                debug!("vtable_methods: trait_method={:?}", trait_method);
+                let def_id = trait_method.def_id;
+
+                // Some methods cannot be called on an object; skip those.
+                if !tcx.is_vtable_safe_method(trait_ref.def_id(), &trait_method) {
+                    debug!("vtable_methods: not vtable safe");
+                    return None;
+                }
+
+                // the method may have some early-bound lifetimes, add
+                // regions for those
+                let substs = Substs::for_item(tcx, def_id,
+                                              |_, _| tcx.types.re_erased,
+                                              |def, _| trait_ref.substs().type_for_def(def));
+
+                // the trait type may have higher-ranked lifetimes in it;
+                // so erase them if they appear, so that we get the type
+                // at some particular call site
+                let substs = tcx.erase_late_bound_regions_and_normalize(&ty::Binder(substs));
+
+                // It's possible that the method relies on where clauses that
+                // do not hold for this particular set of type parameters.
+                // Note that this method could then never be called, so we
+                // do not want to try and trans it, in that case (see #23435).
+                let predicates = tcx.predicates_of(def_id).instantiate_own(tcx, substs);
+                if !normalize_and_test_predicates(tcx, predicates.predicates) {
+                    debug!("vtable_methods: predicates do not hold");
+                    return None;
+                }
+
+                Some((def_id, substs))
+            })
+        }).collect()
+    )
 }
 
 impl<'tcx,O> Obligation<'tcx,O> {
@@ -836,6 +838,7 @@ pub fn provide(providers: &mut ty::maps::Providers) {
         specialization_graph_of: specialize::specialization_graph_provider,
         specializes: specialize::specializes,
         trans_fulfill_obligation: trans::trans_fulfill_obligation,
+        vtable_methods,
         ..*providers
     };
 }
@@ -846,6 +849,7 @@ pub fn provide_extern(providers: &mut ty::maps::Providers) {
         specialization_graph_of: specialize::specialization_graph_provider,
         specializes: specialize::specializes,
         trans_fulfill_obligation: trans::trans_fulfill_obligation,
+        vtable_methods,
         ..*providers
     };
 }

src/librustc/ty/maps/config.rs

@@ -503,6 +503,12 @@ impl<'tcx> QueryDescription for queries::has_clone_closures<'tcx> {
     }
 }
 
+impl<'tcx> QueryDescription for queries::vtable_methods<'tcx> {
+    fn describe(tcx: TyCtxt, key: ty::PolyTraitRef<'tcx> ) -> String {
+        format!("finding all methods for trait {}", tcx.item_path_str(key.def_id()))
+    }
+}
+
 impl<'tcx> QueryDescription for queries::has_copy_closures<'tcx> {
     fn describe(_tcx: TyCtxt, _: CrateNum) -> String {
         format!("seeing if the crate has enabled `Copy` closures")

src/librustc/ty/maps/keys.rs

@@ -143,6 +143,15 @@ impl<'tcx> Key for (ty::ParamEnv<'tcx>, ty::PolyTraitRef<'tcx>) {
     }
 }
 
+impl<'tcx> Key for ty::PolyTraitRef<'tcx>{
+    fn map_crate(&self) -> CrateNum {
+        self.def_id().krate
+    }
+    fn default_span(&self, tcx: TyCtxt) -> Span {
+        tcx.def_span(self.def_id())
+    }
+}
+
 impl<'tcx> Key for Ty<'tcx> {
     fn map_crate(&self) -> CrateNum {
         LOCAL_CRATE

src/librustc/ty/maps/mod.rs

@@ -228,6 +228,8 @@ define_maps! { <'tcx>
     [] fn item_body_nested_bodies: ItemBodyNestedBodies(DefId) -> ExternBodyNestedBodies,
     [] fn const_is_rvalue_promotable_to_static: ConstIsRvaluePromotableToStatic(DefId) -> bool,
     [] fn is_mir_available: IsMirAvailable(DefId) -> bool,
+    [] fn vtable_methods: vtable_methods_node(ty::PolyTraitRef<'tcx>)
+                          -> Rc<Vec<Option<(DefId, &'tcx Substs<'tcx>)>>>,
 
     [] fn trans_fulfill_obligation: fulfill_obligation_dep_node(
         (ty::ParamEnv<'tcx>, ty::PolyTraitRef<'tcx>)) -> Vtable<'tcx, ()>,
@@ -470,3 +472,7 @@ fn collect_and_partition_translation_items_node<'tcx>(_: CrateNum) -> DepConstru
 fn output_filenames_node<'tcx>(_: CrateNum) -> DepConstructor<'tcx> {
     DepConstructor::OutputFilenames
 }
+
+fn vtable_methods_node<'tcx>(trait_ref: ty::PolyTraitRef<'tcx>) -> DepConstructor<'tcx> {
+    DepConstructor::VtableMethods{ trait_ref }
+}

src/librustc/ty/maps/plumbing.rs

@@ -468,8 +468,7 @@ macro_rules! define_maps {
 
         define_provider_struct! {
             tcx: $tcx,
-            input: ($(([$($modifiers)*] [$name] [$K] [$V]))*),
-            output: ()
+            input: ($(([$($modifiers)*] [$name] [$K] [$V]))*)
         }
 
         impl<$tcx> Copy for Providers<$tcx> {}
@@ -480,78 +479,19 @@ macro_rules! define_maps {
 }
 
 macro_rules! define_map_struct {
-    // Initial state
     (tcx: $tcx:tt,
-     input: $input:tt) => {
-        define_map_struct! {
-            tcx: $tcx,
-            input: $input,
-            output: ()
-        }
-    };
-
-    // Final output
-    (tcx: $tcx:tt,
-     input: (),
-     output: ($($output:tt)*)) => {
+     input: ($(([$(modifiers:tt)*] [$($attr:tt)*] [$name:ident]))*)) => {
         pub struct Maps<$tcx> {
             providers: IndexVec<CrateNum, Providers<$tcx>>,
             query_stack: RefCell<Vec<(Span, Query<$tcx>)>>,
-            $($output)*
-        }
-    };
-
-    // Field recognized and ready to shift into the output
-    (tcx: $tcx:tt,
-     ready: ([$($pub:tt)*] [$($attr:tt)*] [$name:ident]),
-     input: $input:tt,
-     output: ($($output:tt)*)) => {
-        define_map_struct! {
-            tcx: $tcx,
-            input: $input,
-            output: ($($output)*
-                     $(#[$attr])* $($pub)* $name: RefCell<QueryMap<queries::$name<$tcx>>>,)
-        }
-    };
-
-    // No modifiers left? This is a private item.
-    (tcx: $tcx:tt,
-     input: (([] $attrs:tt $name:tt) $($input:tt)*),
-     output: $output:tt) => {
-        define_map_struct! {
-            tcx: $tcx,
-            ready: ([] $attrs $name),
-            input: ($($input)*),
-            output: $output
-        }
-    };
-
-    // Skip other modifiers
-    (tcx: $tcx:tt,
-     input: (([$other_modifier:tt $($modifiers:tt)*] $($fields:tt)*) $($input:tt)*),
-     output: $output:tt) => {
-        define_map_struct! {
-            tcx: $tcx,
-            input: (([$($modifiers)*] $($fields)*) $($input)*),
-            output: $output
+            $($(#[$attr])*  $name: RefCell<QueryMap<queries::$name<$tcx>>>,)*
         }
     };
 }
 
 macro_rules! define_provider_struct {
-    // Initial state:
-    (tcx: $tcx:tt, input: $input:tt) => {
-        define_provider_struct! {
-            tcx: $tcx,
-            input: $input,
-            output: ()
-        }
-    };
-
-    // Final state:
     (tcx: $tcx:tt,
-     input: (),
-     output: ($(([$name:ident] [$K:ty] [$R:ty]))*)) => {
+     input: ($(([$($modifiers:tt)*] [$name:ident] [$K:ty] [$R:ty]))*)) => {
         pub struct Providers<$tcx> {
             $(pub $name: for<'a> fn(TyCtxt<'a, $tcx, $tcx>, $K) -> $R,)*
         }
@@ -566,41 +506,6 @@ macro_rules! define_provider_struct {
             }
         }
     };
-
-    // Something ready to shift:
-    (tcx: $tcx:tt,
-     ready: ($name:tt $K:tt $V:tt),
-     input: $input:tt,
-     output: ($($output:tt)*)) => {
-        define_provider_struct! {
-            tcx: $tcx,
-            input: $input,
-            output: ($($output)* ($name $K $V))
-        }
-    };
-
-    // Regular queries produce a `V` only.
-    (tcx: $tcx:tt,
-     input: (([] $name:tt $K:tt $V:tt) $($input:tt)*),
-     output: $output:tt) => {
-        define_provider_struct! {
-            tcx: $tcx,
-            ready: ($name $K $V),
-            input: ($($input)*),
-            output: $output
-        }
-    };
-
-    // Skip modifiers.
-    (tcx: $tcx:tt,
-     input: (([$other_modifier:tt $($modifiers:tt)*] $($fields:tt)*) $($input:tt)*),
-     output: $output:tt) => {
-        define_provider_struct! {
-            tcx: $tcx,
-            input: (([$($modifiers)*] $($fields)*) $($input)*),
-            output: $output
-        }
-    };
 }
 
 
@@ -749,6 +654,7 @@ pub fn force_from_dep_node<'a, 'gcx, 'lcx>(tcx: TyCtxt<'a, 'gcx, 'lcx>,
         DepKind::CodegenUnit |
         DepKind::CompileCodegenUnit |
         DepKind::FulfillObligation |
+        DepKind::VtableMethods |
 
         // These are just odd
         DepKind::Null |

src/librustc_trans/collector.rs

@@ -849,8 +849,8 @@ fn create_trans_items_for_vtable_methods<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
             assert!(!poly_trait_ref.has_escaping_regions());
 
             // Walk all methods of the trait, including those of its supertraits
-            let methods = traits::get_vtable_methods(tcx, poly_trait_ref);
-            let methods = methods.filter_map(|method| method)
+            let methods = tcx.vtable_methods(poly_trait_ref);
+            let methods = methods.iter().cloned().filter_map(|method| method)
                 .map(|(def_id, substs)| ty::Instance::resolve(
                         tcx,
                         ty::ParamEnv::empty(traits::Reveal::All),

src/librustc_trans/meth.rs

@@ -9,7 +9,6 @@
 // except according to those terms.
 
 use llvm::ValueRef;
-use rustc::traits;
 use callee;
 use common::*;
 use builder::Builder;
@@ -87,7 +86,8 @@ pub fn get_vtable<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
 
     if let Some(trait_ref) = trait_ref {
         let trait_ref = trait_ref.with_self_ty(tcx, ty);
-        let methods = traits::get_vtable_methods(tcx, trait_ref).map(|opt_mth| {
+        let methods = tcx.vtable_methods(trait_ref);
+        let methods = methods.iter().cloned().map(|opt_mth| {
             opt_mth.map_or(nullptr, |(def_id, substs)| {
                 callee::resolve_and_get_fn(ccx, def_id, substs)
             })