Rollup merge of #132134 - nnethercote:rm-ResultsVisitable, r=cjgillot

Remove `ResultsVisitable`

`ResultsVisitable` has annoyed me for a while. This PR removes it. Details in the individual commits.

r? `@cjgillot.`

compiler/rustc_borrowck/src/dataflow.rs

@@ -1,93 +1,171 @@
+use std::fmt;
+
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::graph;
 use rustc_index::bit_set::BitSet;
-use rustc_middle::mir::{self, BasicBlock, Body, Location, Place, TerminatorEdges};
+use rustc_middle::mir::{
+    self, BasicBlock, Body, CallReturnPlaces, Location, Place, TerminatorEdges,
+};
 use rustc_middle::ty::{RegionVid, TyCtxt};
 use rustc_mir_dataflow::fmt::DebugWithContext;
 use rustc_mir_dataflow::impls::{EverInitializedPlaces, MaybeUninitializedPlaces};
-use rustc_mir_dataflow::{Analysis, Forward, GenKill, Results, ResultsVisitable};
+use rustc_mir_dataflow::{Analysis, GenKill, JoinSemiLattice, SwitchIntEdgeEffects};
 use tracing::debug;
 
 use crate::{BorrowSet, PlaceConflictBias, PlaceExt, RegionInferenceContext, places_conflict};
 
-/// The results of the dataflow analyses used by the borrow checker.
+// This analysis is different to most others. Its results aren't computed with
-pub(crate) struct BorrowckResults<'a, 'tcx> {
+// `iterate_to_fixpoint`, but are instead composed from the results of three sub-analyses that are
-    pub(crate) borrows: Results<'tcx, Borrows<'a, 'tcx>>,
+// computed individually with `iterate_to_fixpoint`.
-    pub(crate) uninits: Results<'tcx, MaybeUninitializedPlaces<'a, 'tcx>>,
+pub(crate) struct Borrowck<'a, 'tcx> {
-    pub(crate) ever_inits: Results<'tcx, EverInitializedPlaces<'a, 'tcx>>,
+    pub(crate) borrows: Borrows<'a, 'tcx>,
+    pub(crate) uninits: MaybeUninitializedPlaces<'a, 'tcx>,
+    pub(crate) ever_inits: EverInitializedPlaces<'a, 'tcx>,
+}
+
+impl<'a, 'tcx> Analysis<'tcx> for Borrowck<'a, 'tcx> {
+    type Domain = BorrowckDomain<'a, 'tcx>;
+
+    const NAME: &'static str = "borrowck";
+
+    fn bottom_value(&self, body: &mir::Body<'tcx>) -> Self::Domain {
+        BorrowckDomain {
+            borrows: self.borrows.bottom_value(body),
+            uninits: self.uninits.bottom_value(body),
+            ever_inits: self.ever_inits.bottom_value(body),
+        }
+    }
+
+    fn initialize_start_block(&self, _body: &mir::Body<'tcx>, _state: &mut Self::Domain) {
+        // This is only reachable from `iterate_to_fixpoint`, which this analysis doesn't use.
+        unreachable!();
+    }
+
+    fn apply_before_statement_effect(
+        &mut self,
+        state: &mut Self::Domain,
+        stmt: &mir::Statement<'tcx>,
+        loc: Location,
+    ) {
+        self.borrows.apply_before_statement_effect(&mut state.borrows, stmt, loc);
+        self.uninits.apply_before_statement_effect(&mut state.uninits, stmt, loc);
+        self.ever_inits.apply_before_statement_effect(&mut state.ever_inits, stmt, loc);
+    }
+
+    fn apply_statement_effect(
+        &mut self,
+        state: &mut Self::Domain,
+        stmt: &mir::Statement<'tcx>,
+        loc: Location,
+    ) {
+        self.borrows.apply_statement_effect(&mut state.borrows, stmt, loc);
+        self.uninits.apply_statement_effect(&mut state.uninits, stmt, loc);
+        self.ever_inits.apply_statement_effect(&mut state.ever_inits, stmt, loc);
+    }
+
+    fn apply_before_terminator_effect(
+        &mut self,
+        state: &mut Self::Domain,
+        term: &mir::Terminator<'tcx>,
+        loc: Location,
+    ) {
+        self.borrows.apply_before_terminator_effect(&mut state.borrows, term, loc);
+        self.uninits.apply_before_terminator_effect(&mut state.uninits, term, loc);
+        self.ever_inits.apply_before_terminator_effect(&mut state.ever_inits, term, loc);
+    }
+
+    fn apply_terminator_effect<'mir>(
+        &mut self,
+        state: &mut Self::Domain,
+        term: &'mir mir::Terminator<'tcx>,
+        loc: Location,
+    ) -> TerminatorEdges<'mir, 'tcx> {
+        self.borrows.apply_terminator_effect(&mut state.borrows, term, loc);
+        self.uninits.apply_terminator_effect(&mut state.uninits, term, loc);
+        self.ever_inits.apply_terminator_effect(&mut state.ever_inits, term, loc);
+
+        // This return value doesn't matter. It's only used by `iterate_to_fixpoint`, which this
+        // analysis doesn't use.
+        TerminatorEdges::None
+    }
+
+    fn apply_call_return_effect(
+        &mut self,
+        _state: &mut Self::Domain,
+        _block: BasicBlock,
+        _return_places: CallReturnPlaces<'_, 'tcx>,
+    ) {
+        // This is only reachable from `iterate_to_fixpoint`, which this analysis doesn't use.
+        unreachable!();
+    }
+
+    fn apply_switch_int_edge_effects(
+        &mut self,
+        _block: BasicBlock,
+        _discr: &mir::Operand<'tcx>,
+        _apply_edge_effects: &mut impl SwitchIntEdgeEffects<Self::Domain>,
+    ) {
+        // This is only reachable from `iterate_to_fixpoint`, which this analysis doesn't use.
+        unreachable!();
+    }
+}
+
+impl JoinSemiLattice for BorrowckDomain<'_, '_> {
+    fn join(&mut self, _other: &Self) -> bool {
+        // This is only reachable from `iterate_to_fixpoint`, which this analysis doesn't use.
+        unreachable!();
+    }
+}
+
+impl<'tcx, C> DebugWithContext<C> for BorrowckDomain<'_, 'tcx>
+where
+    C: rustc_mir_dataflow::move_paths::HasMoveData<'tcx>,
+{
+    fn fmt_with(&self, ctxt: &C, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str("borrows: ")?;
+        self.borrows.fmt_with(ctxt, f)?;
+        f.write_str(" uninits: ")?;
+        self.uninits.fmt_with(ctxt, f)?;
+        f.write_str(" ever_inits: ")?;
+        self.ever_inits.fmt_with(ctxt, f)?;
+        Ok(())
+    }
+
+    fn fmt_diff_with(&self, old: &Self, ctxt: &C, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        if self == old {
+            return Ok(());
+        }
+
+        if self.borrows != old.borrows {
+            f.write_str("borrows: ")?;
+            self.borrows.fmt_diff_with(&old.borrows, ctxt, f)?;
+            f.write_str("\n")?;
+        }
+
+        if self.uninits != old.uninits {
+            f.write_str("uninits: ")?;
+            self.uninits.fmt_diff_with(&old.uninits, ctxt, f)?;
+            f.write_str("\n")?;
+        }
+
+        if self.ever_inits != old.ever_inits {
+            f.write_str("ever_inits: ")?;
+            self.ever_inits.fmt_diff_with(&old.ever_inits, ctxt, f)?;
+            f.write_str("\n")?;
+        }
+
+        Ok(())
+    }
 }
 
 /// The transient state of the dataflow analyses used by the borrow checker.
-#[derive(Debug)]
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub(crate) struct BorrowckDomain<'a, 'tcx> {
     pub(crate) borrows: <Borrows<'a, 'tcx> as Analysis<'tcx>>::Domain,
     pub(crate) uninits: <MaybeUninitializedPlaces<'a, 'tcx> as Analysis<'tcx>>::Domain,
     pub(crate) ever_inits: <EverInitializedPlaces<'a, 'tcx> as Analysis<'tcx>>::Domain,
 }
 
-impl<'a, 'tcx> ResultsVisitable<'tcx> for BorrowckResults<'a, 'tcx> {
-    type Direction = Forward;
-    type Domain = BorrowckDomain<'a, 'tcx>;
-
-    fn bottom_value(&self, body: &mir::Body<'tcx>) -> Self::Domain {
-        BorrowckDomain {
-            borrows: self.borrows.analysis.bottom_value(body),
-            uninits: self.uninits.analysis.bottom_value(body),
-            ever_inits: self.ever_inits.analysis.bottom_value(body),
-        }
-    }
-
-    fn reset_to_block_entry(&self, state: &mut Self::Domain, block: BasicBlock) {
-        state.borrows.clone_from(self.borrows.entry_set_for_block(block));
-        state.uninits.clone_from(self.uninits.entry_set_for_block(block));
-        state.ever_inits.clone_from(self.ever_inits.entry_set_for_block(block));
-    }
-
-    fn reconstruct_before_statement_effect(
-        &mut self,
-        state: &mut Self::Domain,
-        stmt: &mir::Statement<'tcx>,
-        loc: Location,
-    ) {
-        self.borrows.analysis.apply_before_statement_effect(&mut state.borrows, stmt, loc);
-        self.uninits.analysis.apply_before_statement_effect(&mut state.uninits, stmt, loc);
-        self.ever_inits.analysis.apply_before_statement_effect(&mut state.ever_inits, stmt, loc);
-    }
-
-    fn reconstruct_statement_effect(
-        &mut self,
-        state: &mut Self::Domain,
-        stmt: &mir::Statement<'tcx>,
-        loc: Location,
-    ) {
-        self.borrows.analysis.apply_statement_effect(&mut state.borrows, stmt, loc);
-        self.uninits.analysis.apply_statement_effect(&mut state.uninits, stmt, loc);
-        self.ever_inits.analysis.apply_statement_effect(&mut state.ever_inits, stmt, loc);
-    }
-
-    fn reconstruct_before_terminator_effect(
-        &mut self,
-        state: &mut Self::Domain,
-        term: &mir::Terminator<'tcx>,
-        loc: Location,
-    ) {
-        self.borrows.analysis.apply_before_terminator_effect(&mut state.borrows, term, loc);
-        self.uninits.analysis.apply_before_terminator_effect(&mut state.uninits, term, loc);
-        self.ever_inits.analysis.apply_before_terminator_effect(&mut state.ever_inits, term, loc);
-    }
-
-    fn reconstruct_terminator_effect(
-        &mut self,
-        state: &mut Self::Domain,
-        term: &mir::Terminator<'tcx>,
-        loc: Location,
-    ) {
-        self.borrows.analysis.apply_terminator_effect(&mut state.borrows, term, loc);
-        self.uninits.analysis.apply_terminator_effect(&mut state.uninits, term, loc);
-        self.ever_inits.analysis.apply_terminator_effect(&mut state.ever_inits, term, loc);
-    }
-}
-
 rustc_index::newtype_index! {
     #[orderable]
     #[debug_format = "bw{}"]

compiler/rustc_borrowck/src/lib.rs

@@ -36,13 +36,13 @@ use rustc_middle::mir::*;
 use rustc_middle::query::Providers;
 use rustc_middle::ty::{self, ParamEnv, RegionVid, TyCtxt, TypingMode};
 use rustc_middle::{bug, span_bug};
-use rustc_mir_dataflow::Analysis;
 use rustc_mir_dataflow::impls::{
     EverInitializedPlaces, MaybeInitializedPlaces, MaybeUninitializedPlaces,
 };
 use rustc_mir_dataflow::move_paths::{
     InitIndex, InitLocation, LookupResult, MoveData, MoveOutIndex, MovePathIndex,
 };
+use rustc_mir_dataflow::{Analysis, EntrySets, Results, ResultsVisitor, visit_results};
 use rustc_session::lint::builtin::UNUSED_MUT;
 use rustc_span::{Span, Symbol};
 use smallvec::SmallVec;
@@ -50,7 +50,7 @@ use tracing::{debug, instrument};
 
 use crate::borrow_set::{BorrowData, BorrowSet};
 use crate::consumers::{BodyWithBorrowckFacts, ConsumerOptions};
-use crate::dataflow::{BorrowIndex, BorrowckDomain, BorrowckResults, Borrows};
+use crate::dataflow::{BorrowIndex, Borrowck, BorrowckDomain, Borrows};
 use crate::diagnostics::{AccessKind, IllegalMoveOriginKind, MoveError, RegionName};
 use crate::location::LocationTable;
 use crate::nll::PoloniusOutput;
@@ -221,6 +221,10 @@ fn do_mir_borrowck<'tcx>(
         consumer_options,
     );
 
+    // `flow_inits` is large, so we drop it as soon as possible. This reduces
+    // peak memory usage significantly on some benchmarks.
+    drop(flow_inits);
+
     // Dump MIR results into a file, if that is enabled. This let us
     // write unit-tests, as well as helping with debugging.
     nll::dump_nll_mir(&infcx, body, &regioncx, &opt_closure_req, &borrow_set);
@@ -229,27 +233,6 @@ fn do_mir_borrowck<'tcx>(
     // information.
     nll::dump_annotation(&infcx, body, &regioncx, &opt_closure_req, &opaque_type_values, diags);
 
-    // The various `flow_*` structures can be large. We drop `flow_inits` here
-    // so it doesn't overlap with the others below. This reduces peak memory
-    // usage significantly on some benchmarks.
-    drop(flow_inits);
-
-    let flow_borrows = Borrows::new(tcx, body, &regioncx, &borrow_set).iterate_to_fixpoint(
-        tcx,
-        body,
-        Some("borrowck"),
-    );
-    let flow_uninits = MaybeUninitializedPlaces::new(tcx, body, &move_data).iterate_to_fixpoint(
-        tcx,
-        body,
-        Some("borrowck"),
-    );
-    let flow_ever_inits = EverInitializedPlaces::new(body, &move_data).iterate_to_fixpoint(
-        tcx,
-        body,
-        Some("borrowck"),
-    );
-
     let movable_coroutine =
         // The first argument is the coroutine type passed by value
         if let Some(local) = body.local_decls.raw.get(1)
@@ -334,16 +317,11 @@ fn do_mir_borrowck<'tcx>(
     // Compute and report region errors, if any.
     mbcx.report_region_errors(nll_errors);
 
-    let mut results = BorrowckResults {
+    let mut flow_results = get_flow_results(tcx, body, &move_data, &borrow_set, &regioncx);
-        ever_inits: flow_ever_inits,
+    visit_results(
-        uninits: flow_uninits,
-        borrows: flow_borrows,
-    };
-
-    rustc_mir_dataflow::visit_results(
         body,
         traversal::reverse_postorder(body).map(|(bb, _)| bb),
-        &mut results,
+        &mut flow_results,
         &mut mbcx,
     );
 
@@ -426,6 +404,47 @@ fn do_mir_borrowck<'tcx>(
     (result, body_with_facts)
 }
 
+fn get_flow_results<'a, 'tcx>(
+    tcx: TyCtxt<'tcx>,
+    body: &'a Body<'tcx>,
+    move_data: &'a MoveData<'tcx>,
+    borrow_set: &'a BorrowSet<'tcx>,
+    regioncx: &RegionInferenceContext<'tcx>,
+) -> Results<'tcx, Borrowck<'a, 'tcx>> {
+    // We compute these three analyses individually, but them combine them into
+    // a single results so that `mbcx` can visit them all together.
+    let borrows = Borrows::new(tcx, body, regioncx, borrow_set).iterate_to_fixpoint(
+        tcx,
+        body,
+        Some("borrowck"),
+    );
+    let uninits = MaybeUninitializedPlaces::new(tcx, body, move_data).iterate_to_fixpoint(
+        tcx,
+        body,
+        Some("borrowck"),
+    );
+    let ever_inits = EverInitializedPlaces::new(body, move_data).iterate_to_fixpoint(
+        tcx,
+        body,
+        Some("borrowck"),
+    );
+
+    let analysis = Borrowck {
+        borrows: borrows.analysis,
+        uninits: uninits.analysis,
+        ever_inits: ever_inits.analysis,
+    };
+
+    assert_eq!(borrows.entry_sets.len(), uninits.entry_sets.len());
+    assert_eq!(borrows.entry_sets.len(), ever_inits.entry_sets.len());
+    let entry_sets: EntrySets<'_, Borrowck<'_, '_>> =
+        itertools::izip!(borrows.entry_sets, uninits.entry_sets, ever_inits.entry_sets)
+            .map(|(borrows, uninits, ever_inits)| BorrowckDomain { borrows, uninits, ever_inits })
+            .collect();
+
+    Results { analysis, entry_sets }
+}
+
 pub(crate) struct BorrowckInferCtxt<'tcx> {
     pub(crate) infcx: InferCtxt<'tcx>,
     pub(crate) reg_var_to_origin: RefCell<FxIndexMap<ty::RegionVid, RegionCtxt>>,
@@ -588,14 +607,10 @@ struct MirBorrowckCtxt<'a, 'infcx, 'tcx> {
 // 2. loans made in overlapping scopes do not conflict
 // 3. assignments do not affect things loaned out as immutable
 // 4. moves do not affect things loaned out in any way
-impl<'a, 'tcx, R> rustc_mir_dataflow::ResultsVisitor<'a, 'tcx, R>
+impl<'a, 'tcx> ResultsVisitor<'a, 'tcx, Borrowck<'a, 'tcx>> for MirBorrowckCtxt<'a, '_, 'tcx> {
-    for MirBorrowckCtxt<'a, '_, 'tcx>
-{
-    type Domain = BorrowckDomain<'a, 'tcx>;
-
     fn visit_statement_before_primary_effect(
         &mut self,
-        _results: &mut R,
+        _results: &mut Results<'tcx, Borrowck<'a, 'tcx>>,
         state: &BorrowckDomain<'a, 'tcx>,
         stmt: &'a Statement<'tcx>,
         location: Location,
@@ -667,7 +682,7 @@ impl<'a, 'tcx, R> rustc_mir_dataflow::ResultsVisitor<'a, 'tcx, R>
 
     fn visit_terminator_before_primary_effect(
         &mut self,
-        _results: &mut R,
+        _results: &mut Results<'tcx, Borrowck<'a, 'tcx>>,
         state: &BorrowckDomain<'a, 'tcx>,
         term: &'a Terminator<'tcx>,
         loc: Location,
@@ -780,7 +795,7 @@ impl<'a, 'tcx, R> rustc_mir_dataflow::ResultsVisitor<'a, 'tcx, R>
 
     fn visit_terminator_after_primary_effect(
         &mut self,
-        _results: &mut R,
+        _results: &mut Results<'tcx, Borrowck<'a, 'tcx>>,
         state: &BorrowckDomain<'a, 'tcx>,
         term: &'a Terminator<'tcx>,
         loc: Location,

compiler/rustc_mir_dataflow/src/framework/direction.rs

@@ -4,8 +4,8 @@ use rustc_middle::mir::{
     self, BasicBlock, CallReturnPlaces, Location, SwitchTargets, TerminatorEdges,
 };
 
-use super::visitor::{ResultsVisitable, ResultsVisitor};
+use super::visitor::ResultsVisitor;
-use super::{Analysis, Effect, EffectIndex, SwitchIntTarget};
+use super::{Analysis, Effect, EffectIndex, Results, SwitchIntTarget};
 
 pub trait Direction {
     const IS_FORWARD: bool;
@@ -33,14 +33,14 @@ pub trait Direction {
     where
         A: Analysis<'tcx>;
 
-    fn visit_results_in_block<'mir, 'tcx, D, R>(
+    fn visit_results_in_block<'mir, 'tcx, A>(
-        state: &mut D,
+        state: &mut A::Domain,
         block: BasicBlock,
         block_data: &'mir mir::BasicBlockData<'tcx>,
-        results: &mut R,
+        results: &mut Results<'tcx, A>,
-        vis: &mut impl ResultsVisitor<'mir, 'tcx, R, Domain = D>,
+        vis: &mut impl ResultsVisitor<'mir, 'tcx, A>,
     ) where
-        R: ResultsVisitable<'tcx, Domain = D>;
+        A: Analysis<'tcx>;
 
     fn join_state_into_successors_of<'tcx, A>(
         analysis: &mut A,
@@ -53,7 +53,7 @@ pub trait Direction {
         A: Analysis<'tcx>;
 }
 
-/// Dataflow that runs from the exit of a block (the terminator), to its entry (the first statement).
+/// Dataflow that runs from the exit of a block (terminator), to its entry (the first statement).
 pub struct Backward;
 
 impl Direction for Backward {
@@ -157,32 +157,32 @@ impl Direction for Backward {
         analysis.apply_statement_effect(state, statement, location);
     }
 
-    fn visit_results_in_block<'mir, 'tcx, D, R>(
+    fn visit_results_in_block<'mir, 'tcx, A>(
-        state: &mut D,
+        state: &mut A::Domain,
         block: BasicBlock,
         block_data: &'mir mir::BasicBlockData<'tcx>,
-        results: &mut R,
+        results: &mut Results<'tcx, A>,
-        vis: &mut impl ResultsVisitor<'mir, 'tcx, R, Domain = D>,
+        vis: &mut impl ResultsVisitor<'mir, 'tcx, A>,
     ) where
-        R: ResultsVisitable<'tcx, Domain = D>,
+        A: Analysis<'tcx>,
     {
-        results.reset_to_block_entry(state, block);
+        state.clone_from(results.entry_set_for_block(block));
 
         vis.visit_block_end(state);
 
         // Terminator
         let loc = Location { block, statement_index: block_data.statements.len() };
         let term = block_data.terminator();
-        results.reconstruct_before_terminator_effect(state, term, loc);
+        results.analysis.apply_before_terminator_effect(state, term, loc);
         vis.visit_terminator_before_primary_effect(results, state, term, loc);
-        results.reconstruct_terminator_effect(state, term, loc);
+        results.analysis.apply_terminator_effect(state, term, loc);
         vis.visit_terminator_after_primary_effect(results, state, term, loc);
 
         for (statement_index, stmt) in block_data.statements.iter().enumerate().rev() {
             let loc = Location { block, statement_index };
-            results.reconstruct_before_statement_effect(state, stmt, loc);
+            results.analysis.apply_before_statement_effect(state, stmt, loc);
             vis.visit_statement_before_primary_effect(results, state, stmt, loc);
-            results.reconstruct_statement_effect(state, stmt, loc);
+            results.analysis.apply_statement_effect(state, stmt, loc);
             vis.visit_statement_after_primary_effect(results, state, stmt, loc);
         }
 
@@ -389,32 +389,32 @@ impl Direction for Forward {
         }
     }
 
-    fn visit_results_in_block<'mir, 'tcx, F, R>(
+    fn visit_results_in_block<'mir, 'tcx, A>(
-        state: &mut F,
+        state: &mut A::Domain,
         block: BasicBlock,
         block_data: &'mir mir::BasicBlockData<'tcx>,
-        results: &mut R,
+        results: &mut Results<'tcx, A>,
-        vis: &mut impl ResultsVisitor<'mir, 'tcx, R, Domain = F>,
+        vis: &mut impl ResultsVisitor<'mir, 'tcx, A>,
     ) where
-        R: ResultsVisitable<'tcx, Domain = F>,
+        A: Analysis<'tcx>,
     {
-        results.reset_to_block_entry(state, block);
+        state.clone_from(results.entry_set_for_block(block));
 
         vis.visit_block_start(state);
 
         for (statement_index, stmt) in block_data.statements.iter().enumerate() {
             let loc = Location { block, statement_index };
-            results.reconstruct_before_statement_effect(state, stmt, loc);
+            results.analysis.apply_before_statement_effect(state, stmt, loc);
             vis.visit_statement_before_primary_effect(results, state, stmt, loc);
-            results.reconstruct_statement_effect(state, stmt, loc);
+            results.analysis.apply_statement_effect(state, stmt, loc);
             vis.visit_statement_after_primary_effect(results, state, stmt, loc);
         }
 
         let loc = Location { block, statement_index: block_data.statements.len() };
         let term = block_data.terminator();
-        results.reconstruct_before_terminator_effect(state, term, loc);
+        results.analysis.apply_before_terminator_effect(state, term, loc);
         vis.visit_terminator_before_primary_effect(results, state, term, loc);
-        results.reconstruct_terminator_effect(state, term, loc);
+        results.analysis.apply_terminator_effect(state, term, loc);
         vis.visit_terminator_after_primary_effect(results, state, term, loc);
 
         vis.visit_block_end(state);

compiler/rustc_mir_dataflow/src/framework/graphviz.rs

@@ -544,20 +544,18 @@ impl<D> StateDiffCollector<D> {
     }
 }
 
-impl<'tcx, A> ResultsVisitor<'_, 'tcx, Results<'tcx, A>> for StateDiffCollector<A::Domain>
+impl<'tcx, A> ResultsVisitor<'_, 'tcx, A> for StateDiffCollector<A::Domain>
 where
     A: Analysis<'tcx>,
     A::Domain: DebugWithContext<A>,
 {
-    type Domain = A::Domain;
+    fn visit_block_start(&mut self, state: &A::Domain) {
-
-    fn visit_block_start(&mut self, state: &Self::Domain) {
         if A::Direction::IS_FORWARD {
             self.prev_state.clone_from(state);
         }
     }
 
-    fn visit_block_end(&mut self, state: &Self::Domain) {
+    fn visit_block_end(&mut self, state: &A::Domain) {
         if A::Direction::IS_BACKWARD {
             self.prev_state.clone_from(state);
         }
@@ -566,7 +564,7 @@ where
     fn visit_statement_before_primary_effect(
         &mut self,
         results: &mut Results<'tcx, A>,
-        state: &Self::Domain,
+        state: &A::Domain,
         _statement: &mir::Statement<'tcx>,
         _location: Location,
     ) {
@@ -579,7 +577,7 @@ where
     fn visit_statement_after_primary_effect(
         &mut self,
         results: &mut Results<'tcx, A>,
-        state: &Self::Domain,
+        state: &A::Domain,
         _statement: &mir::Statement<'tcx>,
         _location: Location,
     ) {
@@ -590,7 +588,7 @@ where
     fn visit_terminator_before_primary_effect(
         &mut self,
         results: &mut Results<'tcx, A>,
-        state: &Self::Domain,
+        state: &A::Domain,
         _terminator: &mir::Terminator<'tcx>,
         _location: Location,
     ) {
@@ -603,7 +601,7 @@ where
     fn visit_terminator_after_primary_effect(
         &mut self,
         results: &mut Results<'tcx, A>,
-        state: &Self::Domain,
+        state: &A::Domain,
         _terminator: &mir::Terminator<'tcx>,
         _location: Location,
     ) {

compiler/rustc_mir_dataflow/src/framework/mod.rs

@@ -55,8 +55,8 @@ mod visitor;
 pub use self::cursor::ResultsCursor;
 pub use self::direction::{Backward, Direction, Forward};
 pub use self::lattice::{JoinSemiLattice, MaybeReachable};
-pub use self::results::Results;
+pub use self::results::{EntrySets, Results};
-pub use self::visitor::{ResultsVisitable, ResultsVisitor, visit_results};
+pub use self::visitor::{ResultsVisitor, visit_results};
 
 /// Analysis domains are all bitsets of various kinds. This trait holds
 /// operations needed by all of them.

compiler/rustc_mir_dataflow/src/framework/results.rs

@@ -18,7 +18,7 @@ use crate::errors::{
     DuplicateValuesFor, PathMustEndInFilename, RequiresAnArgument, UnknownFormatter,
 };
 
-type EntrySets<'tcx, A> = IndexVec<BasicBlock, <A as Analysis<'tcx>>::Domain>;
+pub type EntrySets<'tcx, A> = IndexVec<BasicBlock, <A as Analysis<'tcx>>::Domain>;
 
 /// A dataflow analysis that has converged to fixpoint.
 #[derive(Clone)]
@@ -27,7 +27,7 @@ where
     A: Analysis<'tcx>,
 {
     pub analysis: A,
-    pub(super) entry_sets: EntrySets<'tcx, A>,
+    pub entry_sets: EntrySets<'tcx, A>,
 }
 
 impl<'tcx, A> Results<'tcx, A>
@@ -51,7 +51,7 @@ where
         &mut self,
         body: &'mir mir::Body<'tcx>,
         blocks: impl IntoIterator<Item = BasicBlock>,
-        vis: &mut impl ResultsVisitor<'mir, 'tcx, Self, Domain = A::Domain>,
+        vis: &mut impl ResultsVisitor<'mir, 'tcx, A>,
     ) {
         visit_results(body, blocks, self, vis)
     }
@@ -59,7 +59,7 @@ where
     pub fn visit_reachable_with<'mir>(
         &mut self,
         body: &'mir mir::Body<'tcx>,
-        vis: &mut impl ResultsVisitor<'mir, 'tcx, Self, Domain = A::Domain>,
+        vis: &mut impl ResultsVisitor<'mir, 'tcx, A>,
     ) {
         let blocks = traversal::reachable(body);
         visit_results(body, blocks.map(|(bb, _)| bb), self, vis)

compiler/rustc_mir_dataflow/src/framework/visitor.rs

@@ -4,15 +4,15 @@ use super::{Analysis, Direction, Results};
 
 /// Calls the corresponding method in `ResultsVisitor` for every location in a `mir::Body` with the
 /// dataflow state at that location.
-pub fn visit_results<'mir, 'tcx, D, R>(
+pub fn visit_results<'mir, 'tcx, A>(
     body: &'mir mir::Body<'tcx>,
     blocks: impl IntoIterator<Item = BasicBlock>,
-    results: &mut R,
+    results: &mut Results<'tcx, A>,
-    vis: &mut impl ResultsVisitor<'mir, 'tcx, R, Domain = D>,
+    vis: &mut impl ResultsVisitor<'mir, 'tcx, A>,
 ) where
-    R: ResultsVisitable<'tcx, Domain = D>,
+    A: Analysis<'tcx>,
 {
-    let mut state = results.bottom_value(body);
+    let mut state = results.analysis.bottom_value(body);
 
     #[cfg(debug_assertions)]
     let reachable_blocks = mir::traversal::reachable_as_bitset(body);
@@ -22,23 +22,23 @@ pub fn visit_results<'mir, 'tcx, D, R>(
         assert!(reachable_blocks.contains(block));
 
         let block_data = &body[block];
-        R::Direction::visit_results_in_block(&mut state, block, block_data, results, vis);
+        A::Direction::visit_results_in_block(&mut state, block, block_data, results, vis);
     }
 }
 
-/// A visitor over the results of an `Analysis`. The type parameter `R` is the results type being
+/// A visitor over the results of an `Analysis`.
-/// visited.
+pub trait ResultsVisitor<'mir, 'tcx, A>
-pub trait ResultsVisitor<'mir, 'tcx, R> {
+where
-    type Domain;
+    A: Analysis<'tcx>,
-
+{
-    fn visit_block_start(&mut self, _state: &Self::Domain) {}
+    fn visit_block_start(&mut self, _state: &A::Domain) {}
 
     /// Called with the `before_statement_effect` of the given statement applied to `state` but not
     /// its `statement_effect`.
     fn visit_statement_before_primary_effect(
         &mut self,
-        _results: &mut R,
+        _results: &mut Results<'tcx, A>,
-        _state: &Self::Domain,
+        _state: &A::Domain,
         _statement: &'mir mir::Statement<'tcx>,
         _location: Location,
     ) {
@@ -48,19 +48,19 @@ pub trait ResultsVisitor<'mir, 'tcx, R> {
     /// statement applied to `state`.
     fn visit_statement_after_primary_effect(
         &mut self,
-        _results: &mut R,
+        _results: &mut Results<'tcx, A>,
-        _state: &Self::Domain,
+        _state: &A::Domain,
         _statement: &'mir mir::Statement<'tcx>,
         _location: Location,
     ) {
     }
 
-    /// Called with the `before_terminator_effect` of the given terminator applied to `state` but not
+    /// Called with the `before_terminator_effect` of the given terminator applied to `state` but
-    /// its `terminator_effect`.
+    /// not its `terminator_effect`.
     fn visit_terminator_before_primary_effect(
         &mut self,
-        _results: &mut R,
+        _results: &mut Results<'tcx, A>,
-        _state: &Self::Domain,
+        _state: &A::Domain,
         _terminator: &'mir mir::Terminator<'tcx>,
         _location: Location,
     ) {
@@ -72,109 +72,12 @@ pub trait ResultsVisitor<'mir, 'tcx, R> {
     /// The `call_return_effect` (if one exists) will *not* be applied to `state`.
     fn visit_terminator_after_primary_effect(
         &mut self,
-        _results: &mut R,
+        _results: &mut Results<'tcx, A>,
-        _state: &Self::Domain,
+        _state: &A::Domain,
         _terminator: &'mir mir::Terminator<'tcx>,
         _location: Location,
     ) {
     }
 
-    fn visit_block_end(&mut self, _state: &Self::Domain) {}
+    fn visit_block_end(&mut self, _state: &A::Domain) {}
-}
-
-/// Things that can be visited by a `ResultsVisitor`.
-///
-/// This trait exists so that we can visit the results of one or more dataflow analyses
-/// simultaneously.
-pub trait ResultsVisitable<'tcx> {
-    type Direction: Direction;
-    type Domain;
-
-    /// Creates an empty `Domain` to hold the transient state for these dataflow results.
-    ///
-    /// The value of the newly created `Domain` will be overwritten by `reset_to_block_entry`
-    /// before it can be observed by a `ResultsVisitor`.
-    fn bottom_value(&self, body: &mir::Body<'tcx>) -> Self::Domain;
-
-    fn reset_to_block_entry(&self, state: &mut Self::Domain, block: BasicBlock);
-
-    fn reconstruct_before_statement_effect(
-        &mut self,
-        state: &mut Self::Domain,
-        statement: &mir::Statement<'tcx>,
-        location: Location,
-    );
-
-    fn reconstruct_statement_effect(
-        &mut self,
-        state: &mut Self::Domain,
-        statement: &mir::Statement<'tcx>,
-        location: Location,
-    );
-
-    fn reconstruct_before_terminator_effect(
-        &mut self,
-        state: &mut Self::Domain,
-        terminator: &mir::Terminator<'tcx>,
-        location: Location,
-    );
-
-    fn reconstruct_terminator_effect(
-        &mut self,
-        state: &mut Self::Domain,
-        terminator: &mir::Terminator<'tcx>,
-        location: Location,
-    );
-}
-
-impl<'tcx, A> ResultsVisitable<'tcx> for Results<'tcx, A>
-where
-    A: Analysis<'tcx>,
-{
-    type Domain = A::Domain;
-    type Direction = A::Direction;
-
-    fn bottom_value(&self, body: &mir::Body<'tcx>) -> Self::Domain {
-        self.analysis.bottom_value(body)
-    }
-
-    fn reset_to_block_entry(&self, state: &mut Self::Domain, block: BasicBlock) {
-        state.clone_from(self.entry_set_for_block(block));
-    }
-
-    fn reconstruct_before_statement_effect(
-        &mut self,
-        state: &mut Self::Domain,
-        stmt: &mir::Statement<'tcx>,
-        loc: Location,
-    ) {
-        self.analysis.apply_before_statement_effect(state, stmt, loc);
-    }
-
-    fn reconstruct_statement_effect(
-        &mut self,
-        state: &mut Self::Domain,
-        stmt: &mir::Statement<'tcx>,
-        loc: Location,
-    ) {
-        self.analysis.apply_statement_effect(state, stmt, loc);
-    }
-
-    fn reconstruct_before_terminator_effect(
-        &mut self,
-        state: &mut Self::Domain,
-        term: &mir::Terminator<'tcx>,
-        loc: Location,
-    ) {
-        self.analysis.apply_before_terminator_effect(state, term, loc);
-    }
-
-    fn reconstruct_terminator_effect(
-        &mut self,
-        state: &mut Self::Domain,
-        term: &mir::Terminator<'tcx>,
-        loc: Location,
-    ) {
-        self.analysis.apply_terminator_effect(state, term, loc);
-    }
 }

compiler/rustc_mir_dataflow/src/lib.rs

@@ -18,8 +18,8 @@ pub use self::drop_flag_effects::{
     move_path_children_matching, on_all_children_bits, on_lookup_result_bits,
 };
 pub use self::framework::{
-    Analysis, Backward, Direction, Forward, GenKill, JoinSemiLattice, MaybeReachable, Results,
+    Analysis, Backward, Direction, EntrySets, Forward, GenKill, JoinSemiLattice, MaybeReachable,
-    ResultsCursor, ResultsVisitable, ResultsVisitor, SwitchIntEdgeEffects, fmt, graphviz, lattice,
+    Results, ResultsCursor, ResultsVisitor, SwitchIntEdgeEffects, fmt, graphviz, lattice,
     visit_results,
 };
 use self::move_paths::MoveData;

compiler/rustc_mir_dataflow/src/points.rs

@@ -3,7 +3,7 @@ use rustc_index::interval::SparseIntervalMatrix;
 use rustc_index::{Idx, IndexVec};
 use rustc_middle::mir::{self, BasicBlock, Body, Location};
 
-use crate::framework::{ResultsVisitable, ResultsVisitor, visit_results};
+use crate::framework::{Analysis, Results, ResultsVisitor, visit_results};
 
 /// Maps between a `Location` and a `PointIndex` (and vice versa).
 pub struct DenseLocationMap {
@@ -95,14 +95,14 @@ rustc_index::newtype_index! {
 }
 
 /// Add points depending on the result of the given dataflow analysis.
-pub fn save_as_intervals<'tcx, N, R>(
+pub fn save_as_intervals<'tcx, N, A>(
     elements: &DenseLocationMap,
     body: &mir::Body<'tcx>,
-    mut results: R,
+    mut results: Results<'tcx, A>,
 ) -> SparseIntervalMatrix<N, PointIndex>
 where
     N: Idx,
-    R: ResultsVisitable<'tcx, Domain = BitSet<N>>,
+    A: Analysis<'tcx, Domain = BitSet<N>>,
 {
     let values = SparseIntervalMatrix::new(elements.num_points());
     let mut visitor = Visitor { elements, values };
@@ -120,16 +120,15 @@ struct Visitor<'a, N: Idx> {
     values: SparseIntervalMatrix<N, PointIndex>,
 }
 
-impl<'mir, 'tcx, R, N> ResultsVisitor<'mir, 'tcx, R> for Visitor<'_, N>
+impl<'mir, 'tcx, A, N> ResultsVisitor<'mir, 'tcx, A> for Visitor<'_, N>
 where
+    A: Analysis<'tcx, Domain = BitSet<N>>,
     N: Idx,
 {
-    type Domain = BitSet<N>;
-
     fn visit_statement_after_primary_effect(
         &mut self,
-        _results: &mut R,
+        _results: &mut Results<'tcx, A>,
-        state: &Self::Domain,
+        state: &A::Domain,
         _statement: &'mir mir::Statement<'tcx>,
         location: Location,
     ) {
@@ -142,8 +141,8 @@ where
 
     fn visit_terminator_after_primary_effect(
         &mut self,
-        _results: &mut R,
+        _results: &mut Results<'tcx, A>,
-        state: &Self::Domain,
+        state: &A::Domain,
         _terminator: &'mir mir::Terminator<'tcx>,
         location: Location,
     ) {

compiler/rustc_mir_transform/src/coroutine.rs

@@ -68,11 +68,11 @@ use rustc_middle::ty::{
     self, CoroutineArgs, CoroutineArgsExt, GenericArgsRef, InstanceKind, Ty, TyCtxt, TypingMode,
 };
 use rustc_middle::{bug, span_bug};
-use rustc_mir_dataflow::Analysis;
 use rustc_mir_dataflow::impls::{
     MaybeBorrowedLocals, MaybeLiveLocals, MaybeRequiresStorage, MaybeStorageLive,
 };
 use rustc_mir_dataflow::storage::always_storage_live_locals;
+use rustc_mir_dataflow::{Analysis, Results, ResultsVisitor};
 use rustc_span::Span;
 use rustc_span::def_id::{DefId, LocalDefId};
 use rustc_span::symbol::sym;
@@ -817,9 +817,9 @@ impl ops::Deref for CoroutineSavedLocals {
 /// computation; see `CoroutineLayout` for more.
 fn compute_storage_conflicts<'mir, 'tcx>(
     body: &'mir Body<'tcx>,
-    saved_locals: &CoroutineSavedLocals,
+    saved_locals: &'mir CoroutineSavedLocals,
     always_live_locals: BitSet<Local>,
-    mut requires_storage: rustc_mir_dataflow::Results<'tcx, MaybeRequiresStorage<'mir, 'tcx>>,
+    mut requires_storage: Results<'tcx, MaybeRequiresStorage<'mir, 'tcx>>,
 ) -> BitMatrix<CoroutineSavedLocal, CoroutineSavedLocal> {
     assert_eq!(body.local_decls.len(), saved_locals.domain_size());
 
@@ -877,15 +877,13 @@ struct StorageConflictVisitor<'a, 'tcx> {
     eligible_storage_live: BitSet<Local>,
 }
 
-impl<'a, 'tcx, R> rustc_mir_dataflow::ResultsVisitor<'a, 'tcx, R>
+impl<'a, 'tcx> ResultsVisitor<'a, 'tcx, MaybeRequiresStorage<'a, 'tcx>>
     for StorageConflictVisitor<'a, 'tcx>
 {
-    type Domain = BitSet<Local>;
-
     fn visit_statement_before_primary_effect(
         &mut self,
-        _results: &mut R,
+        _results: &mut Results<'tcx, MaybeRequiresStorage<'a, 'tcx>>,
-        state: &Self::Domain,
+        state: &BitSet<Local>,
         _statement: &'a Statement<'tcx>,
         loc: Location,
     ) {
@@ -894,8 +892,8 @@ impl<'a, 'tcx, R> rustc_mir_dataflow::ResultsVisitor<'a, 'tcx, R>
 
     fn visit_terminator_before_primary_effect(
         &mut self,
-        _results: &mut R,
+        _results: &mut Results<'tcx, MaybeRequiresStorage<'a, 'tcx>>,
-        state: &Self::Domain,
+        state: &BitSet<Local>,
         _terminator: &'a Terminator<'tcx>,
         loc: Location,
     ) {

compiler/rustc_mir_transform/src/dataflow_const_prop.rs

@@ -941,16 +941,12 @@ fn try_write_constant<'tcx>(
     interp_ok(())
 }
 
-impl<'mir, 'tcx> ResultsVisitor<'mir, 'tcx, Results<'tcx, ConstAnalysis<'_, 'tcx>>>
+impl<'mir, 'tcx> ResultsVisitor<'mir, 'tcx, ConstAnalysis<'_, 'tcx>> for Collector<'_, 'tcx> {
-    for Collector<'_, 'tcx>
-{
-    type Domain = State<FlatSet<Scalar>>;
-
     #[instrument(level = "trace", skip(self, results, statement))]
     fn visit_statement_before_primary_effect(
         &mut self,
         results: &mut Results<'tcx, ConstAnalysis<'_, 'tcx>>,
-        state: &Self::Domain,
+        state: &State<FlatSet<Scalar>>,
         statement: &'mir Statement<'tcx>,
         location: Location,
     ) {
@@ -972,7 +968,7 @@ impl<'mir, 'tcx> ResultsVisitor<'mir, 'tcx, Results<'tcx, ConstAnalysis<'_, 'tcx
     fn visit_statement_after_primary_effect(
         &mut self,
         results: &mut Results<'tcx, ConstAnalysis<'_, 'tcx>>,
-        state: &Self::Domain,
+        state: &State<FlatSet<Scalar>>,
         statement: &'mir Statement<'tcx>,
         location: Location,
     ) {
@@ -997,7 +993,7 @@ impl<'mir, 'tcx> ResultsVisitor<'mir, 'tcx, Results<'tcx, ConstAnalysis<'_, 'tcx
     fn visit_terminator_before_primary_effect(
         &mut self,
         results: &mut Results<'tcx, ConstAnalysis<'_, 'tcx>>,
-        state: &Self::Domain,
+        state: &State<FlatSet<Scalar>>,
         terminator: &'mir Terminator<'tcx>,
         location: Location,
     ) {