Reduce the scope of allow(rustc::potential_query_instability) in rustc_trait_selection

Make InferCtxtExt use a FxIndexMap

This should be faster, because the map is only being used to iterate,
which is supposed to be faster with the IndexMap

Make the user_computed_preds use an IndexMap

It is being used mostly for iteration, so the change shouldn't result in
a perf hit

Make the RegionDeps fields use an IndexMap

This change could be a perf hit. Both `larger` and `smaller` are used
for iteration, but they are also used for insertions.

Make types_without_default_bounds use an IndexMap

It uses extend, but it also iterates and removes items. Not sure if
this will be a perf hit.

Make InferTtxt.reported_trait_errors use an IndexMap

This change brought a lot of other changes. The map seems to have been
mostly used for iteration, so the performance shouldn't suffer.

Add FIXME to change ProvisionalEvaluationCache.map to use an IndexMap

Right now this results in a perf hit. IndexMap doesn't have
the `drain_filter` API, so in `on_completion` we now need to iterate two
times over the map.

diff --git a/compiler/rustc_hir_analysis/src/check/compare_method.rs b/compiler/rustc_hir_analysis/src/check/compare_method.rs
index 0e8ac17fb71b1588ad19e937cf03f413ca24b73e..818db4186d60ab291bd08e07f8e680861e26c019 100644 (file)
--- a/compiler/rustc_hir_analysis/src/check/compare_method.rs
+++ b/compiler/rustc_hir_analysis/src/check/compare_method.rs
@@ -1,7 +1,7 @@
 use super::potentially_plural_count;
 use crate::errors::LifetimesOrBoundsMismatchOnTrait;
 use hir::def_id::{DefId, LocalDefId};
-use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_data_structures::fx::{FxHashMap, FxIndexSet};
 use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticId, ErrorGuaranteed};
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
@@ -256,7 +256,7 @@ fn compare_predicate_entailment<'tcx>(
     // Compute placeholder form of impl and trait method tys.
     let tcx = infcx.tcx;
 
-    let mut wf_tys = FxHashSet::default();
+    let mut wf_tys = FxIndexSet::default();
 
     let impl_sig = infcx.replace_bound_vars_with_fresh_vars(
         impl_m_span,
@@ -479,7 +479,7 @@ pub fn collect_trait_impl_trait_tys<'tcx>(
     let trait_sig = ocx.normalize(norm_cause.clone(), param_env, unnormalized_trait_sig);
     let trait_return_ty = trait_sig.output();
 
-    let wf_tys = FxHashSet::from_iter(
+    let wf_tys = FxIndexSet::from_iter(
         unnormalized_trait_sig.inputs_and_output.iter().chain(trait_sig.inputs_and_output.iter()),
     );
 

diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
index e2c967d0b0836e03a2936ca434f091b761d92cda..6a12db9d36ade2bd13f39124b8042617a0dede7a 100644 (file)
--- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs
+++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -1,7 +1,7 @@
 use crate::constrained_generic_params::{identify_constrained_generic_params, Parameter};
 use hir::def::DefKind;
 use rustc_ast as ast;
-use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
 use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticBuilder, ErrorGuaranteed};
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
@@ -412,7 +412,7 @@ fn check_gat_where_clauses(tcx: TyCtxt<'_>, associated_items: &[hir::TraitItemRe
                                 .iter()
                                 .copied()
                                 .collect::<Vec<_>>(),
-                            &FxHashSet::default(),
+                            &FxIndexSet::default(),
                             gat_def_id.def_id,
                             gat_generics,
                         )
@@ -462,10 +462,10 @@ fn check_gat_where_clauses(tcx: TyCtxt<'_>, associated_items: &[hir::TraitItemRe
             .into_iter()
             .filter(|clause| match clause.kind().skip_binder() {
                 ty::PredicateKind::RegionOutlives(ty::OutlivesPredicate(a, b)) => {
-                    !region_known_to_outlive(tcx, gat_hir, param_env, &FxHashSet::default(), a, b)
+                    !region_known_to_outlive(tcx, gat_hir, param_env, &FxIndexSet::default(), a, b)
                 }
                 ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(a, b)) => {
-                    !ty_known_to_outlive(tcx, gat_hir, param_env, &FxHashSet::default(), a, b)
+                    !ty_known_to_outlive(tcx, gat_hir, param_env, &FxIndexSet::default(), a, b)
                 }
                 _ => bug!("Unexpected PredicateKind"),
             })
@@ -547,7 +547,7 @@ fn gather_gat_bounds<'tcx, T: TypeFoldable<'tcx>>(
     param_env: ty::ParamEnv<'tcx>,
     item_hir: hir::HirId,
     to_check: T,
-    wf_tys: &FxHashSet<Ty<'tcx>>,
+    wf_tys: &FxIndexSet<Ty<'tcx>>,
     gat_def_id: LocalDefId,
     gat_generics: &'tcx ty::Generics,
 ) -> Option<FxHashSet<ty::Predicate<'tcx>>> {
@@ -654,7 +654,7 @@ fn ty_known_to_outlive<'tcx>(
     tcx: TyCtxt<'tcx>,
     id: hir::HirId,
     param_env: ty::ParamEnv<'tcx>,
-    wf_tys: &FxHashSet<Ty<'tcx>>,
+    wf_tys: &FxIndexSet<Ty<'tcx>>,
     ty: Ty<'tcx>,
     region: ty::Region<'tcx>,
 ) -> bool {
@@ -671,7 +671,7 @@ fn region_known_to_outlive<'tcx>(
     tcx: TyCtxt<'tcx>,
     id: hir::HirId,
     param_env: ty::ParamEnv<'tcx>,
-    wf_tys: &FxHashSet<Ty<'tcx>>,
+    wf_tys: &FxIndexSet<Ty<'tcx>>,
     region_a: ty::Region<'tcx>,
     region_b: ty::Region<'tcx>,
 ) -> bool {
@@ -695,7 +695,7 @@ fn resolve_regions_with_wf_tys<'tcx>(
     tcx: TyCtxt<'tcx>,
     id: hir::HirId,
     param_env: ty::ParamEnv<'tcx>,
-    wf_tys: &FxHashSet<Ty<'tcx>>,
+    wf_tys: &FxIndexSet<Ty<'tcx>>,
     add_constraints: impl for<'a> FnOnce(&'a InferCtxt<'tcx>, &'a RegionBoundPairs<'tcx>),
 ) -> bool {
     // Unfortunately, we have to use a new `InferCtxt` each call, because

diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index d5be9983ea7c60b0c0f2286d9c0225bee2a8f2e8..ccba197dc80b75c58bdb415410ed38ef4a406751 100644 (file)
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -10,6 +10,7 @@
 
 use crate::traits::{self, ObligationCause, PredicateObligations, TraitEngine, TraitEngineExt};
 
+use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::sync::Lrc;
 use rustc_data_structures::undo_log::Rollback;
@@ -294,7 +295,7 @@ pub struct InferCtxt<'tcx> {
 
     /// the set of predicates on which errors have been reported, to
     /// avoid reporting the same error twice.
-    pub reported_trait_errors: RefCell<FxHashMap<Span, Vec<ty::Predicate<'tcx>>>>,
+    pub reported_trait_errors: RefCell<FxIndexMap<Span, Vec<ty::Predicate<'tcx>>>>,
 
     pub reported_closure_mismatch: RefCell<FxHashSet<(Span, Option<Span>)>>,
 

diff --git a/compiler/rustc_trait_selection/src/lib.rs b/compiler/rustc_trait_selection/src/lib.rs
index 5d52aa07523012329dada901b8e2e2cebf978a0c..2dce18e2d3cad263dc36aeacd3469aa18c1ec9ac 100644 (file)
--- a/compiler/rustc_trait_selection/src/lib.rs
+++ b/compiler/rustc_trait_selection/src/lib.rs
@@ -10,7 +10,6 @@
 //!
 //! This API is completely unstable and subject to change.
 
-#![allow(rustc::potential_query_instability)]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(box_patterns)]
 #![feature(control_flow_enum)]

diff --git a/compiler/rustc_trait_selection/src/traits/auto_trait.rs b/compiler/rustc_trait_selection/src/traits/auto_trait.rs
index ed34ab95ad6c00009e96e4b4b81062525d40d427..188f8bb7e2a58cd9815015a278b35dc4154936e9 100644 (file)
--- a/compiler/rustc_trait_selection/src/traits/auto_trait.rs
+++ b/compiler/rustc_trait_selection/src/traits/auto_trait.rs
@@ -12,7 +12,7 @@
 use rustc_middle::ty::visit::TypeVisitable;
 use rustc_middle::ty::{PolyTraitRef, Region, RegionVid};
 
-use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
 
 use std::collections::hash_map::Entry;
 use std::collections::VecDeque;
@@ -27,8 +27,8 @@ pub enum RegionTarget<'tcx> {
 
 #[derive(Default, Debug, Clone)]
 pub struct RegionDeps<'tcx> {
-    larger: FxHashSet<RegionTarget<'tcx>>,
-    smaller: FxHashSet<RegionTarget<'tcx>>,
+    larger: FxIndexSet<RegionTarget<'tcx>>,
+    smaller: FxIndexSet<RegionTarget<'tcx>>,
 }
 
 pub enum AutoTraitResult<A> {
@@ -266,7 +266,7 @@ fn evaluate_predicates(
         }));
 
         let computed_preds = param_env.caller_bounds().iter();
-        let mut user_computed_preds: FxHashSet<_> = user_env.caller_bounds().iter().collect();
+        let mut user_computed_preds: FxIndexSet<_> = user_env.caller_bounds().iter().collect();
 
         let mut new_env = param_env;
         let dummy_cause = ObligationCause::dummy();
@@ -389,7 +389,7 @@ fn evaluate_predicates(
     /// not just one specific lifetime (e.g., `'static`).
     fn add_user_pred(
         &self,
-        user_computed_preds: &mut FxHashSet<ty::Predicate<'tcx>>,
+        user_computed_preds: &mut FxIndexSet<ty::Predicate<'tcx>>,
         new_pred: ty::Predicate<'tcx>,
     ) {
         let mut should_add_new = true;
@@ -585,7 +585,7 @@ fn evaluate_nested_obligations(
         &self,
         ty: Ty<'_>,
         nested: impl Iterator<Item = Obligation<'tcx, ty::Predicate<'tcx>>>,
-        computed_preds: &mut FxHashSet<ty::Predicate<'tcx>>,
+        computed_preds: &mut FxIndexSet<ty::Predicate<'tcx>>,
         fresh_preds: &mut FxHashSet<ty::Predicate<'tcx>>,
         predicates: &mut VecDeque<ty::PolyTraitPredicate<'tcx>>,
         select: &mut SelectionContext<'_, 'tcx>,

diff --git a/compiler/rustc_trait_selection/src/traits/engine.rs b/compiler/rustc_trait_selection/src/traits/engine.rs
index 21516c93efb53aa8b33e681938a61c1701f54d35..91bf5f0b39e73828336b5e25b452efe65090f475 100644 (file)
--- a/compiler/rustc_trait_selection/src/traits/engine.rs
+++ b/compiler/rustc_trait_selection/src/traits/engine.rs
@@ -4,7 +4,7 @@
 use super::TraitEngine;
 use super::{ChalkFulfillmentContext, FulfillmentContext};
 use crate::infer::InferCtxtExt;
-use rustc_data_structures::fx::FxHashSet;
+use rustc_data_structures::fx::FxIndexSet;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_infer::infer::at::ToTrace;
 use rustc_infer::infer::canonical::{
@@ -153,10 +153,10 @@ pub fn assumed_wf_types(
         param_env: ty::ParamEnv<'tcx>,
         span: Span,
         def_id: LocalDefId,
-    ) -> FxHashSet<Ty<'tcx>> {
+    ) -> FxIndexSet<Ty<'tcx>> {
         let tcx = self.infcx.tcx;
         let assumed_wf_types = tcx.assumed_wf_types(def_id);
-        let mut implied_bounds = FxHashSet::default();
+        let mut implied_bounds = FxIndexSet::default();
         let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
         let cause = ObligationCause::misc(span, hir_id);
         for ty in assumed_wf_types {

diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
index c7dee4a18ac5dd9ba7f95d949dfb7a9102a6e051..2525b9fdd470bb578247176cb1b99c1fea417c5e 100644 (file)
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
@@ -14,7 +14,7 @@
 use crate::traits::specialize::to_pretty_impl_header;
 use on_unimplemented::OnUnimplementedNote;
 use on_unimplemented::TypeErrCtxtExt as _;
-use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
 use rustc_errors::{
     pluralize, struct_span_err, Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed,
     MultiSpan, Style,
@@ -378,7 +378,7 @@ struct ErrorDescriptor<'tcx> {
             index: Option<usize>, // None if this is an old error
         }
 
-        let mut error_map: FxHashMap<_, Vec<_>> = self
+        let mut error_map: FxIndexMap<_, Vec<_>> = self
             .reported_trait_errors
             .borrow()
             .iter()

diff --git a/compiler/rustc_trait_selection/src/traits/outlives_bounds.rs b/compiler/rustc_trait_selection/src/traits/outlives_bounds.rs
index b1a161c353637610c4d3fd3caad65ed26bb0219e..e1092a788e32b5df96786eb40146d485a096a43f 100644 (file)
--- a/compiler/rustc_trait_selection/src/traits/outlives_bounds.rs
+++ b/compiler/rustc_trait_selection/src/traits/outlives_bounds.rs
@@ -2,7 +2,7 @@
 use crate::traits::query::type_op::{self, TypeOp, TypeOpOutput};
 use crate::traits::query::NoSolution;
 use crate::traits::ObligationCause;
-use rustc_data_structures::fx::FxHashSet;
+use rustc_data_structures::fx::FxIndexSet;
 use rustc_hir as hir;
 use rustc_hir::HirId;
 use rustc_middle::ty::{self, ParamEnv, Ty};
@@ -22,7 +22,7 @@ fn implied_bounds_tys(
         &'a self,
         param_env: ty::ParamEnv<'tcx>,
         body_id: hir::HirId,
-        tys: FxHashSet<Ty<'tcx>>,
+        tys: FxIndexSet<Ty<'tcx>>,
     ) -> Bounds<'a, 'tcx>;
 }
 
@@ -103,7 +103,7 @@ fn implied_bounds_tys(
         &'a self,
         param_env: ParamEnv<'tcx>,
         body_id: HirId,
-        tys: FxHashSet<Ty<'tcx>>,
+        tys: FxIndexSet<Ty<'tcx>>,
     ) -> Bounds<'a, 'tcx> {
         tys.into_iter()
             .map(move |ty| {

diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index 84be1ced520febd20370d7188a7252ad12c377ba..f0d9a1c91397935de96721a3e662cbc8601c452f 100644 (file)
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -2,6 +2,12 @@
 //!
 //! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/resolution.html#selection
 
+// FIXME: The `map` field in ProvisionalEvaluationCache should be changed to
+// a `FxIndexMap` to avoid query instability, but right now it causes a perf regression. This would be
+// fixed or at least lightened by the addition of the `drain_filter` method to `FxIndexMap`
+// Relevant: https://github.com/rust-lang/rust/pull/103723 and https://github.com/bluss/indexmap/issues/242
+#![allow(rustc::potential_query_instability)]
+
 use self::EvaluationResult::*;
 use self::SelectionCandidate::*;
 
@@ -24,7 +30,8 @@
 use crate::traits::project::ProjectAndUnifyResult;
 use crate::traits::project::ProjectionCacheKeyExt;
 use crate::traits::ProjectionCacheKey;
-use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
+use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_errors::{Diagnostic, ErrorGuaranteed};
 use rustc_hir as hir;

diff --git a/compiler/rustc_trait_selection/src/traits/specialize/mod.rs b/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
index c891658582a0a89b34222703a47894385c45a5e3..43819b3f490b1907655d5da45d252cff2210803c 100644 (file)
--- a/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
@@ -16,7 +16,7 @@
 use crate::infer::{InferCtxt, InferOk, TyCtxtInferExt};
 use crate::traits::select::IntercrateAmbiguityCause;
 use crate::traits::{self, coherence, FutureCompatOverlapErrorKind, ObligationCause};
-use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
+use rustc_data_structures::fx::FxIndexSet;
 use rustc_errors::{struct_span_err, DiagnosticBuilder, EmissionGuarantee};
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_middle::ty::{self, ImplSubject, TyCtxt};
@@ -435,7 +435,7 @@ pub(crate) fn to_pretty_impl_header(tcx: TyCtxt<'_>, impl_def_id: DefId) -> Opti
 
     // FIXME: Currently only handles ?Sized.
     //        Needs to support ?Move and ?DynSized when they are implemented.
-    let mut types_without_default_bounds = FxHashSet::default();
+    let mut types_without_default_bounds = FxIndexSet::default();
     let sized_trait = tcx.lang_items().sized_trait();
 
     if !substs.is_empty() {