WIP

Author: amandasystems

compiler/rustc_borrowck/src/region_infer/values.rs

@@ -1,24 +1,18 @@
 use std::fmt::Debug;
 use std::rc::Rc;
 
-use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
+use rustc_data_structures::fx::FxHashSet;
 use rustc_index::Idx;
 use rustc_index::bit_set::SparseBitMatrix;
 use rustc_index::interval::{IntervalSet, SparseIntervalMatrix};
 use rustc_middle::mir::{BasicBlock, Location};
-use rustc_middle::ty::{self, RegionVid};
+use rustc_middle::ty::RegionVid;
 use rustc_mir_dataflow::points::{DenseLocationMap, PointIndex};
 use tracing::debug;
 
 use crate::BorrowIndex;
 use crate::polonius::LiveLoans;
 
-rustc_index::newtype_index! {
-    /// A single integer representing a `ty::Placeholder`.
-    #[debug_format = "PlaceholderIndex({})"]
-    pub(crate) struct PlaceholderIndex {}
-}
-
 /// An individual element in a region value -- the value of a
 /// particular region variable consists of a set of these elements.
 #[derive(Debug, Clone, PartialEq)]
@@ -186,23 +180,6 @@ impl LivenessValues {
     }
 }
 
-/// Maps from `ty::PlaceholderRegion` values that are used in the rest of
-/// rustc to the internal `PlaceholderIndex` values that are used in
-/// NLL.
-#[derive(Debug, Default)]
-pub(crate) struct PlaceholderIndices {
-    indices: FxIndexSet<ty::PlaceholderRegion>,
-}
-
-// FIXME(amandasystems) Can we get rid of this one too?
-impl PlaceholderIndices {
-    /// Returns the `PlaceholderIndex` for the inserted `PlaceholderRegion`
-    pub(crate) fn insert(&mut self, placeholder: ty::PlaceholderRegion) -> PlaceholderIndex {
-        let (index, _) = self.indices.insert_full(placeholder);
-        index.into()
-    }
-}
-
 /// Stores the full values for a set of regions (in contrast to
 /// `LivenessValues`, which only stores those points in the where a
 /// region is live). The full value for a region may contain points in

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -5,13 +5,13 @@ use std::{fmt, iter, mem};
 
 use rustc_abi::FieldIdx;
 use rustc_data_structures::frozen::Frozen;
-use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
+use rustc_data_structures::fx::{FxHashMap, FxIndexMap, FxIndexSet};
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::LocalDefId;
 use rustc_hir::lang_items::LangItem;
-use rustc_index::{IndexSlice, IndexVec};
+use rustc_index::IndexSlice;
 use rustc_infer::infer::canonical::QueryRegionConstraints;
 use rustc_infer::infer::outlives::env::RegionBoundPairs;
 use rustc_infer::infer::region_constraints::RegionConstraintData;
@@ -46,7 +46,7 @@ use crate::member_constraints::MemberConstraintSet;
 use crate::polonius::legacy::{PoloniusFacts, PoloniusLocationTable};
 use crate::polonius::{PoloniusContext, PoloniusLivenessContext};
 use crate::region_infer::TypeTest;
-use crate::region_infer::values::{LivenessValues, PlaceholderIndex, PlaceholderIndices};
+use crate::region_infer::values::LivenessValues;
 use crate::session_diagnostics::{MoveUnsized, SimdIntrinsicArgConst};
 use crate::type_check::free_region_relations::{CreateResult, UniversalRegionRelations};
 use crate::universal_regions::{DefiningTy, UniversalRegions};
@@ -110,8 +110,7 @@ pub(crate) fn type_check<'tcx>(
     location_map: Rc<DenseLocationMap>,
 ) -> MirTypeckResults<'tcx> {
     let mut constraints = MirTypeckRegionConstraints {
-        placeholder_indices: PlaceholderIndices::default(),
-        placeholder_index_to_region: IndexVec::default(),
+        placeholder_to_region: FxHashMap::default(),
         liveness_constraints: LivenessValues::with_specific_points(Rc::clone(&location_map)),
         outlives_constraints: OutlivesConstraintSet::default(),
         member_constraints: MemberConstraintSet::default(),
@@ -236,16 +235,10 @@ pub(crate) struct MirTypeckResults<'tcx> {
 /// A collection of region constraints that must be satisfied for the
 /// program to be considered well-typed.
 pub(crate) struct MirTypeckRegionConstraints<'tcx> {
-    /// Maps from a `ty::Placeholder` to the corresponding
-    /// `PlaceholderIndex` bit that we will use for it.
-    placeholder_indices: PlaceholderIndices,
-
-    /// Each time we add a placeholder to `placeholder_indices`, we
-    /// also create a corresponding "representative" region vid for
-    /// that wraps it. This vector tracks those. This way, when we
-    /// convert the same `ty::RePlaceholder(p)` twice, we can map to
-    /// the same underlying `RegionVid`.
-    placeholder_index_to_region: IndexVec<PlaceholderIndex, ty::Region<'tcx>>,
+    /// For each placeholder we create a corresponding representative region vid.
+    /// This map tracks those. This way, when we convert the same `ty::RePlaceholder(p)`
+    /// twice, we can map to the same underlying `RegionVid`.
+    placeholder_to_region: FxHashMap<ty::PlaceholderRegion, ty::Region<'tcx>>,
 
     /// In general, the type-checker is not responsible for enforcing
     /// liveness constraints; this job falls to the region inferencer,
@@ -273,16 +266,10 @@ impl<'tcx> MirTypeckRegionConstraints<'tcx> {
         infcx: &InferCtxt<'tcx>,
         placeholder: ty::PlaceholderRegion,
     ) -> ty::Region<'tcx> {
-        let placeholder_index = self.placeholder_indices.insert(placeholder);
-        match self.placeholder_index_to_region.get(placeholder_index) {
-            Some(&v) => v,
-            None => {
-                let origin = NllRegionVariableOrigin::Placeholder(placeholder);
-                let region = infcx.next_nll_region_var_in_universe(origin, placeholder.universe);
-                self.placeholder_index_to_region.push(region);
-                region
-            }
-        }
+        *self.placeholder_to_region.entry(placeholder).or_insert_with(|| {
+            let origin = NllRegionVariableOrigin::Placeholder(placeholder);
+            infcx.next_nll_region_var_in_universe(origin, placeholder.universe)
+        })
     }
 }